Safe Mooring Practice [PDF]

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THE MOORING SERIES – Edition 2: The Theory of Mooring Safe Mooring Practice Maintenance of Mooring Systems

TRAINER’S GUIDE

Author: Sean Gallagher

Videotel Productions 84 Newman Street London W1T 3EU, UK Tel: +44 (0)20 7299 1800 Fax: +44 (0)20 299 1818 Email: [email protected]

THE MOORING SERIES – Edition 2: The Theory of Mooring Safe Mooring Practice Maintenance of Mooring Systems A VIDEOTEL PRODUCTION in association with

THE STEAMSHIP MUTUAL UNDERWRITING ASSOCIATION (BERMUDA) LTD.

The Producers would like to thank the following for their kind assistance:

The Masters, Officers and Crews of MV Coral Star, MV Lord Hinton, MV Maersk Rosyth Andromeda Shipping BP Shipping ChevronTexaco Shipping Company LLC IndoChina Ship Management (UK) Ltd International Maritime Organization Jebsens Ship Management Keystone Shipping Company The Maersk Company Maritime and Coastguard Agency Oil Companies International Marine Forum (OCIMF) Shell International Trading & Shipping Company Ltd United European Car Carriers CONSULTANTS: PRODUCER: WRITER/ DIRECTOR: PRINT AUTHOR: PRINT PRODUCER:

TOBY DEAN ROBIN JACKSON GEORGE BEKES SEAN GALLAGHER BARBARA STEINBERG

Warning: Any unauthorised copying, hiring, lending, exhibition diffusion, sale, public performance or other exploitation of this video is strictly prohibited and may result in prosecution. COPYRIGHT Videotel 2004 This video is intended to reflect the best available techniques and practices at the time of production, it is intended purely as comment. No responsibility is accepted by Videotel, or by any firm, corporation or organisation who or which has been in any way concerned with the production or authorised translation, supply or sale of this video for accuracy of any information given hereon or for any omission herefrom.

Contents 1. 1.1 1.2 1.3 1.4

How to use this training package Who this training package is aimed at How to use this Guidebook and the videos Preparing a training session Running a training session

2. 2.1 2.2 2.3 2.4

Theory of mooring Primary forces and factors affecting mooring Mooring lines Winches Printed guides and electronic aids to mooring

Page 1 1 1 2 2 4 4 6 11 15

3. Safe mooring practice Preparing to moor 3.1 Approaching the berth: risk assessment 3.2 Making ready to moor 3.3 Mooring, tying up and keeping station 3.4 Handling mooring lines Winches, windlasses, chains & anchors 3.5 Use of winches 3.6 Windlasses, chains and anchors Mooring line systems 3.7 The ideal mooring system 3.8 Stoppers 3.9 Emergency action Special or hazardous conditions 3.10 Bad weather operations 3.11 Mooring at buoys Working with tugs 3.12 Tug operations and towing procedures

16

4. 4.1 4.2 4.3 4.4 4.5

46 46 48 54 54 55

Maintenance of mooring systems Wire lines Synthetic lines Winches Tails and shackles Fairleads, windlasses, chains and anchors

16 16 18 20 25 25 27 29 31 32 35 41

5. Further information and reading

55

Appendix 1: Assessment quizzes

56

Appendix 2: Performance and characteristics of mooring lines 61 Appendix 3: Case studies of mooring accidents

70

1. How to use this training package 1.1 Who this training package is aimed at The Mooring Series is a training package for mariners on all types and sizes of vessel. It is aimed at helping those crewmembers who form your mooring party to berth a vessel with skill and in safety. Although the types and positions of winches, mooring lines and other items of equipment can vary on different vessels, this training package sets out the ‘best-practice’ mooring procedures which should apply to any ship and to any port or terminal where you may dock. Parts of the package The Mooring Series training package is made up of this Trainer’s Guide and three programmes entitled: 1. Theory of mooring 2. Safe mooring practice 3. Maintenance of mooring systems You may have some or all of these programmes on board. However many of them you have, you can still use this Guide to learn about those aspects of mooring shown in all of the programmes.

1.2 How to use this Guide and the programmes Appointing a Trainer One person should be appointed to be the Trainer, preferably an officer who supervises the ship’s mooring party. To get maximum benefit from this training package the Trainer should aim to follow the instructions in this Guide as closely as possible. Learning the training material During the course of a training session you will be able to instruct crewmembers about (a) the theory of mooring, (b) safe mooring practice, and (c) the maintenance of mooring systems, or (d) all three topics together. Each of these three aspects of mooring is covered in this Guide, and whatever programmes you have can be used to illustrate what is being explained. It is important that the information in this training package is related to your own vessel’s mooring equipment. You must make sure you fully understand every aspect of the safe mooring procedures described in the videos and in this Guide, and you should learn everything you can about your own vessel’s mooring equipment. You can do this, for example, by reading the manufacturers’ operating and safety manuals for different items of mooring equipment. We recommend you read this Guide through to the end before watching the programmes. Make sure you understand it. Next, watch whichever of the programmes you have all the way through. If you have all three, start with the Theory of Mooring, then go on to Safe Mooring Practice, and finish off with Maintenance of Mooring Systems. Afterwards, watch them again, this time making notes about how the various scenes in each tie in with the additional information and the diagrams contained in this Guide. You will be 1

SAFE MOORING PROCEDURES

using this additional information to help explain the procedures the crewmembers will see in the programme(s). There is a lot of information contained in this package and more than one training session may be required.

1.3 Preparing a training session During each training session you will need: ● pens and notepads for each person being trained ●

a large flipchart and different coloured marker pens, or a blackboard and chalk, or large pieces of paper you can tape onto a bulkhead

●

different types of mooring lines, each about 2 metres in length (have at least samples of all the types of line in use aboard your vessel, but if possible have samples of other wire and synthetic lines the crew may have to handle on other occasions)

●

if possible, have examples of frayed or damaged lines, or examples of other defective items of mooring equipment, such as a damaged part of a winch which has been kept from a previous repair, or a worn brake lining

●

examples of other items used in mooring, such as stoppers; correctly and incorrectly spliced lines, and so on.

1.4 Running a training session Setting the scene for the attendees First, explain to the crewmembers what the training session is about and what you will expect them to learn and be able to do once they have completed it. Explain to them how the session will be run and what they should be doing during it. Tell them there will be a quiz at the end to check they have correctly understood everything. Getting their full attention Mention to the crew how they might be tempted to look around with interest at a port they are visiting for the first time. They may be thinking about their next meal, or what videos will be shown in the mess that evening. Tell them that it is during such short moments of inattention while engaged in mooring operations that many seafarers have been injured and killed. Examples of accidents which have happened during mooring Use the case studies described in Appendix 3 to get the group to focus on carrying out mooring procedures safely. Photocopy the case studies you think are most relevant to your crewmembers and hand them out. Begin by discussing the many sorts of things which can go wrong and can cause accidents during mooring operations. Ask the group to discuss whether any of the accidents described in the case studies could ever happen to them. Ask them to share their experiences of accidents and ‘near misses’. Showing the programmes If you have it, start by showing the Theory of Mooring, and then Safe Mooring Practice, followed by the Maintenance of Mooring Systems. Show each video all the way through to the end. Then run them once more, but this time put the programme on ‘pause’ after each scene or part of the mooring procedure. Get the crew to

SAFE MOORING PROCEDURES

2

discuss what they have just seen. Use the additional information and the diagrams in this Guide to help you direct and broaden the discussion. Encouraging discussion Ask the crew how what they have seen relates to the equipment on board your vessel, and how it relates to the way they have carried out mooring operations previously. For example, ask them when they saw such tasks being done properly; have they seen the tasks being done dangerously? Is their own method of doing such a task different to what was shown? Why is that? Encourage them to discuss the practical aspects of carrying out the different parts of the mooring procedures shown in each scene. Practical training on deck To better understand certain aspects of safe mooring procedures, you should also carry out some training on deck, such as: ● marking out the snapback zones and fouling areas around each winch ●

identifying deck and winch blind spots

●

or examining some winches to see if anyone can spot if there are any signs of potential defects, such as maybe patches of excess oil, or no grease showing on exposed machinery, or too much rust on brake rubbing surfaces for instance.

How much information does the group need? Some sections of this Guide go into a lot of detail about equipment and procedures for mooring. For example, there is a lot of information about the construction and properties of different types of mooring lines in Appendix 2. In section 3 there is also a lot of information about tug operations. Do all your crewmembers need to know about each of these aspects of mooring operations? It is for you, the Trainer, to decide. Every training group will vary as to how much they need to learn to be able to carry out their mooring duties efficiently and in safety, and you can tailor the comprehensive information provided in this Guide to suit your requirements. Checking everyone has understood: three assessment quizzes At the end of the training session hand out photocopies of the quizzes in Appendix 1 to each of the group and get them to answer the questions. Check the answers to ensure everyone has fully understood everything you have told them. If anyone scores less than 80% of correct answers in each section of the quiz, then you should go back over those parts which have not been understood.

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SAFE MOORING PROCEDURES

2. Theory of mooring 2.1 Primary forces and factors affecting mooring Seven main factors can affect a ship when it is either being moored or is already moored: ●

the ship’s own manoeuvres, if it is still underway

●

the manoeuvres of any accompanying tugboats

●

wind

●

tide and currents

●

surge from other vessels

●

waves and swell

●

the weight and positioning of cargo when either being loaded or unloaded, affecting: - list - trim - change in draught and, consequently, freeboard

While in harbour or alongside properly positioned buoys, the strongest natural forces affecting a vessel’s mooring stability are wind, currents and tide. Most modern terminals and ports will have mooring systems positioned with any current running from the direction of the ship’s stern or bows. It will have been designed to cope with the forces caused by up to a 3 knot current, or by a 0.75 knot current if it is on the beam. Most well designed mooring systems will also be able to cope with winds of up to 60 knots. Wind The speed and force of the wind increases the further above sea level it is blowing. For example, a 30 knot wind down at sea level can be very much stronger at deck level, and it might even be much stronger still higher up above deck level, maybe reaching 60 knots or more. Such strong winds impacting high up on a vessel’s cargo of containers or any other cargo stacked on the deck could possibly have a major effect on a ship’s movements while it is tied up. A vessel’s freeboard and cargo can therefore become very important factors in whether a mooring might quickly become unsafe if a wind suddenly blows up. Currents A current usually only becomes important in mooring when three factors combine: ● if the vessel has a deep draught (draft); ●

when there is a current coming from abeam;

●

and if there is little clearance between the keel and the seabed.

When this situation occurs, then the beam current will be forced around the ship’s bow or stern, or both, and will also increase in speed as it passes beneath the keel. These effects will have to be taken into consideration during mooring procedures. The same effects can happen when the current is coming from either astern or ahead, although the forces created from those directions are not so great as from a beam current.

SAFE MOORING PROCEDURES

4

50t

90t

150t

200t

CURRENT (1kt)

0.5 x draught

0.2 x draught

2 x draught 5 x draught

Fig 1: The effect on the force of a current caused by different draughts and underkeel clearances Calculating the forces When the speed of either the wind or a current increases, their force gets far, far stronger than you might expect. This is because their force is proportional to the square of their speed. For example, the force of a 60 knot wind is four times greater than that caused by a 30 knot wind. Similarly, the force from a 3 knot current is nine times greater than that caused a 1 knot current. So when moored, keep a regular check on the speed of the wind and the current, and calculate any changes in the forces which might be affecting your vessel’s mooring – they could be very different to what they were a few hours before.

Summer DWT 18,000 loaded ballast 70,000 loaded ballast 200,000 loaded ballast

Transverse forces Tonnes Wind Current 33 30 102 7 72 62 210 8 106 132 378 15

Longitudinal forces Tonnes Wind Current 27 15 48 5 37 35 52 13 49 73 76 23

Table 1: Examples of the sort of weight of force which a 60 knot wind and a 3 knot current can exert on vessels of various sizes Tide Some mooring positions will be affected in ports where there is a large tidal range causing different berth levels at high and low tide. The ship will naturally move up and down alongside its berth as the tide ebbs and flows, causing either increased tension in the mooring lines as it rises, with the resulting danger of a line parting, or decreased tension and slackness as it falls, with the danger of the ship drifting off position as a result. Compensate for these hazards by correctly setting any self-tensioning winches and by setting a good deck watch to regularly check the mooring lines.

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SAFE MOORING PROCEDURES

Strong winds and fast currents In the event of very strong winds while moored, it might be better to ballast the ship down, since the danger to a mooring system from strong winds impacting on a high freeboard are greater than the danger from the increased force of a current running beneath a narrow underkeel clearance.

Surge, waves and swell The effects of surge from passing ships, waves and swell are difficult to foresee. A sensible precaution is to ask the berthing pilot and harbour authorities for advice if you think there is the possibility of unusually large waves or swell reaching your vessel, or if there is constant and heavy ship traffic in the vicinity of your mooring. It is particularly important to take additional measures with your mooring system if your vessel is fully loaded, has a deep draft with little underkeel clearance, and is moored close to a shipping lane. In such circumstances there is a danger of particularly heavy surge from a passing vessel forcing your ship away from the dock and perhaps causing the lines to part. Cargo and ballast Loading and unloading cargo can have all sorts of effects on the disposition of your vessel. The most obvious are on its freeboard and its gross weight. The sequence and method of moving cargo can also affect the stability of the vessel, its orientation, or its susceptibility to the forces of wind or currents. Changes taking place to the ship’s disposition during loading and unloading of cargo must be constantly monitored, so that any necessary adjustments can be made to the mooring system. Other factors affecting mooring Aside from the normal, physical factors which can affect the way a ship is moored, there can occasionally be other aspects which have to be considered, such as a jetty in poor condition, or one which has dangerous equipment adjacent to the vessel’s assigned berth, or if there are too many mooring lines from other vessels attached to the bollards to which your vessel is being directed. Although a Master is seldom able to choose his berth; instead going wherever he is directed by the port authority, or to that part of the jetty where his cargo lies, nevertheless he is entitled to refuse to tie up at an unsafe berth if he considers it presents an unacceptable risk.

2.2 Mooring lines Mooring lines come in a wide variety of materials, construction and sizes. Very few vessels still use mooring lines made of natural fibre materials, such as hemp. Instead, the three main types of mooring lines in use today are made of : ●

steel wire, with a core of more steel or of synthetic fibre

●

conventional synthetic fibres (‘plastic/nylon’ rope-like materials)

●

high modulus synthetic fibre (extra-high strength ‘plastic/nylon’ rope-like materials)

SAFE MOORING PROCEDURES

6

Mooring lines made of steel wire are often referred to as ‘wires’ or ‘cables’, while those made of either synthetic or natural fibre are often referred to as ‘ropes’. In general, larger vessels are usually equipped with wire mooring lines fitted to self-stowing winches, which usually come as standard equipment on newer ships. Smaller vessels may be equipped with synthetic fibre lines, also mostly on self-stowing winches. Larger vessels, however, may also have synthetic fibre lines fore and aft for use as first line ashore, because their light weight and buoyancy make them easier to handle when the ship is still some distance away from its berth, and can be used to heave the vessel alongside the berth before their wire mooring lines are deployed. The many different types and grades of materials from which mooring lines are made each have their own advantages and disadvantages. Since you will probably have to handle a great many mooring lines during your time at sea, it is important to understand their characteristics and handling properties and what different precautions and maintenance procedures you may have to adopt when using different types of lines. Strength and elasticity The two most important factors regarding any type of mooring line are its strength and its elasticity. The ‘strength’ of a line means how big a load or weight it will take before it parts, and this is usually measured in terms of ‘Minimum Breaking Load’ (MBL). A line’s ‘elasticity’ is how much it will stretch when subjected to a force, and this is usually measured in terms of ‘stretch under load’. Most conventional synthetic fibre lines have a much lower MBL, and also stretch far more than steel wire lines. However, steel wire lines and both conventional and high modulus synthetic fibre lines such as aramid and HMPE (explained more fully in Appendix 2) each have their own advantages and disadvantages. Mooring lines made of steel wire, with their great strength and small amount of elasticity, are regarded as the main components of a large vessel’s mooring system. However, high modulus synthetic lines can be as strong as those made from steel wire, size for size. Choosing which type of lines to use in different positions depends on the situation and conditions at the ship’s berth. Wire mooring lines Wire mooring lines are mostly used on large vessels because they are: ● far stronger per each millimetre of thickness than conventional synthetic fibre lines (although, high modulus synthetic fibre lines have strength equal to wire) ●

able to be stored away on drum winches where the biggest reel is usually only suited to lines up to 44mm in diameter, so not having to sacrifice a high breaking load in order to get all the length of the line onto the drum.

Synthetic mooring lines On one hand, synthetic lines have the advantage of being lighter, more flexible, easier to handle and longer lasting than wire lines. On the other hand, however, they are more easily chafed and damaged than lines made from steel wire.

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SAFE MOORING PROCEDURES

While high-modulus synthetic lines have very little elasticity (typically only about 1–2%, making them almost comparable to wire lines in their lack of elasticity), conventional synthetic lines have much greater elasticity, which can be considered either a benefit or a drawback to safe mooring, depending on a vessel’s mooring circumstances at the time. Used properly, the greater elasticity of conventional synthetic lines can provide for better load sharing between the different mooring lines, so making them less susceptible to sudden changes in their dynamic load caused by tide, waves or swell, or during loading. Used improperly, the elasticity of conventional synthetic fibre lines can cause safety problems. For small and medium sized vessels, the use of conventional synthetic fibre lines by themselves can be entirely suitable for mooring. For very large vessels, however, steel wire cables or high modulus synthetic fibre lines are more often used as the main components in a ship’s mooring system. Understanding elasticity, length, dip and bend Elasticity Understanding the elasticity (already briefly mentioned in the preceding section) of the lines you are using for mooring is important for two reasons. Firstly, it helps you understand how much load or weight different types of line, and of different lengths and thickness, will be bearing when moored. Secondly, it helps you understand how much the lines might stretch under those loads, and what this can mean to the ship’s safety. How elastic a line can be will depend on several factors, including the material it is made from; its diameter (thickness), and the load it is bearing. At maximum load a wire cable might stretch just 1.5% of its length. By comparison, however, a conventional synthetic nylon rope can stretch as much as a huge 30% of its length under maximum load. A thicker line will stretch less than one which has a smaller diameter. The heavier the load the more a line may stretch. All these factors have to be taken into consideration when planning how to moor your vessel. So, with some berths perhaps needing mooring lines of up to 100 metres each, this can mean that conventional synthetic ropes alone may not be able to provide a vessel with the accuracy of positioning needed for the safe loading and unloading of cargo by cranes, hoses or other dockside equipment. Because of their stretching capacity, a mooring system made up entirely of conventional synthetic lines might allow a vessel to drift away from its mooring. Length When two mooring lines of the same thickness and material are run out alongside each other, but with one being tied up to a bollard twice as far away as the other, then the shorter line will bear 2/3 of the vessel’s load while the longer line will bear only 1/3 of the load. If possible, therefore, two identical lines warped off in the same direction should be attached to bollards the same distance away. The ‘Dip’ effect If a mooring line has to be run round a corner or be set at an angle along its length for some reason, such as when it passes through a fairlead and angles sharply down to a bollard on the quayside perhaps ten metres below, then its restraining power on the vessel is considerably SAFE MOORING PROCEDURES

8

reduced. The restraining power of such an angled mooring line is proportional to its angle, so the bigger the angle in the line then the more the line’s power is reduced. For example, a mooring line angled at 30º has only 87% of its normal horizontal strength, and a line angled at 45º has only 71% of its normal strength.

30º

Fig. 2: A short mooring line from a ship to a bollard close to and below its fairlead can mean the line loses much of its holding power. The ‘Bend’ effect Taking a wire line round a sharp edge or corner might not only cause it damage, it can also lead to loss of load-holding power. If a wire line is looped horizontally at too big an angle around something on deck, this also can cause it to lose load-holding power. In such circumstances the forces of wind and current can be greater than a line’s breaking point on its outboard section, and if the winch brake doesn’t render in time then the line can part. T2 = Theoretical max. loading after allowing for friction ± 150 tonnes re

To sho

150º

T1 = Holding power of winch - say 100 tonnes

Fig. 3: A mooring line running at an angle from a quayside bollard to a deck winch can have its MBL considerably reduced, with the amount of loss of MBL depending on the degree of angle in the line. Can you mix your lines? Using a mix of steel wire and synthetic fibre lines for a mooring system can have advantages, but can also require increased vigilance because of the greater elasticity of synthetic lines and the other factors which can affect them. It is important that members of a mooring party understand these factors. A careful and well-planned mix of wire and synthetic lines can provide a vessel with the combined best advantages of both types of lines. The wire cables can provide strength to the mooring system, while the accompanying synthetic rope lines can allow the normal movement 9

SAFE MOORING PROCEDURES

of the vessel, such as rolling and riding on a swell. Synthetic lines, too, are better than wire cables for absorbing sudden shock loads, such as a surge from a passing ship. In such circumstances the elasticity of conventional synthetic lines can take the strain, whereas the rigid wire cables may part with the sudden shock. When using wire and conventional synthetic lines together can be a bad mix When two mooring lines of identical length and maximum breaking load and with the same lead are used alongside each other, but one is a wire line capable of stretching up to 1.5% of its length under its maximum load, and the other is a synthetic rope capable of stretching up to 30% under its own maximum load, then the wire line will take 95% of any extra load put upon it, while the synthetic rope will only bear 5% of any extra load. Figures 4(a) and 4(b) demonstrate the disparate strains on lines of different materials and lengths being used alongside each other.

Steel = 47T T Polypropylene = 2 Nylon = 1T

T

100

Fig. 4 (a): The effects of the forces of currents and winds on a vessel using a system of mooring lines made of different materials, and so with different MBLs, has to be considered.

Length of line

MBL

Same size & type hawser

30m

60m

< 25T 150

T

> 50T

Fig. 4 (b): As the lengths of the lines in a ship’s mooring system may vary, so also will the MBL of each line vary in relation to the length of each, with the MBL of a mooring line decreasing as its length increases. The best solution To achieve the best mooring system for your vessel - and there are no cast-iron rules for what constitutes a ‘perfect’ mooring system - the answer is to fully understand the characteristics, capabilities and limitations of all the different types and sizes of wire cables and synthetic fibre ropes your vessel carries, and know which combinations are best for different berthing conditions. SAFE MOORING PROCEDURES

10

If your vessel should use a mixture of synthetic fibre ropes and wire cables then the best and safest practice is, whenever possible, to use the wire cables for the spring lines and the synthetic ropes for heaving alongside the berth and then as the head, breast and stern lines in the mooring system. Performance and characteristics of mooring lines The widely varying performance and characteristics of the many different types of wire and synthetic mooring lines are set out in more detail in Appendix 2 at the end of this Guide.

Check with the port Some ports will not accept a vessel which only has high modulus synthetic fibre lines. If your vessel uses these alone and you will be mooring in an unfamiliar port, you should check in advance with the authorities that your synthetic mooring lines are acceptable.

2.3 Winches Winches are powered either by electric or hydraulic motors. Steam winches are still used on some vessels, but are not common today. Most medium or large-sized vessels are now usually equipped with hydraulic winches, while electric winches are more usually found on smaller ships. Render and heave Whether electric or hydraulic, all mooring winches are affected to some extent by a feature known as their ‘render-to-heave ratio’. ‘Render’ is the amount of force needed to turn a winch which is set to heave, to pull in its line, when power is applied. The render value of a winch is always constant. When the winch is working to heave in a line attached to a load, ‘heave’ refers to the maximum load weight which that level of ‘render’ power going into the winch can safely handle. Different types and makes of winch have different render-to-heave ratios, but a fairly standard one is a ‘render’ force of 35 tonnes needed to turn a winch and give it a ‘heave’ power of 22 tonnes. A winch’s ‘heave’ power will always be less than its ‘render’ power. This is because there is a loss of pulling power which is used by running the winch. For example: the amount of ‘render’ pulling power going into the winch is 35 tonnes. The amount of actual load-bearing ‘heave’ power the winch is really capable of handling is 22 tonnes. The difference is 13 tonnes. The render-to-heave ratio of any winch generally lies somewhere between 1.17 and 2.3, depending on the type of winch. You need to know a winch’s heave power to calculate whether a winch and its mooring line are suitable for a particular heaving task. It is also useful to understand that it will be impossible, and dangerous, to try to heave in a load once a winch has reached its maximum render power. Remember that a winch brake’s holding power is always greater than its heaving power and so if the brake starts to render, or slip, it will be impossible for the winch to heave in unless whatever is causing the slippage, whether excessive load or some sort of obstruction, is reduced. 11

SAFE MOORING PROCEDURES

Render, holding power and line breaking point: working out when a line might part A winch’s holding power (as distinct to its heaving power, which is different) is also affected by its render value. For example, if a winch’s render value is 35 tonnes and its brake holding power (see pages 12/13) is 65 tonnes, then its total holding power is 100 tonnes. But if this winch is using a mooring line with a MBL of 108 tonnes and allowing for a reduction in its strength of 20% from wear and tear, then its breaking load is reduced to just 86 tonnes. This line would then be in danger of parting when used with that winch which has a combined holding power of 100 tonnes.

Self-tensioning winches Many vessels are fitted with self-tensioning winches, so crewmembers do not need to have to spend long periods checking mooring lines. These winches can be pre-set to pay out a mooring line when the line’s tension starts to exceed its setting, or to heave in the line if it slackens below that setting. The use of self-tensioning winches can, however, cause a problem with safety. This is because the winch’s limit is its render load, which is smaller than what can be held on the brake. If a vessel is moored alongside a quay and its springline winches are set to automatically selftension, it is possible for them to be activated by the movement caused by wind or currents. As each winch automatically either pays out or takes in as the vessel see-saws, bit by bit the ship can pull itself along the quay, possibly moving it out of position away from loading arms and perhaps breaking hoses connected to the vessel.

Hoses

Fig. 5: A vessel shifting at its moorings can cause hoses and loading arms to break, possibly resulting in pollution or expensive damage. Such movement can be checked by also using mooring lines secured to bollards or to braked winches. If possible, regularly inspect a mooring system which is using tension winches while the vessel is at its berth. Winch brakes The holding power of a winch’s brake varies from vessel to vessel, although it will always be greater than the render power of the winch. A winch’s brake holding power depends on how many layers of line are on its drum, with its holding power decreasing as layers of line increase on the drum. SAFE MOORING PROCEDURES

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1st layer R1

R2

RB

RB

Brake holding power 55 tonnes RB = Brake Radius

Fig. 6a: With a smaller layer mooring line around its drum, this winch has a brake holding power of 55 tonnes

4th layer

Brake holding power reduced to 40 tonnes as radius R2 increases to 4th layer

Fig. 6b: With 4 layers of mooring line now around its drum, the winch’s brake holding power has been reduced to 40 tonnes.

Non-split drum winches The brake holding power for winches with non-split drums is usually given in terms of the number of layers of line it takes on. Although it is good practice to see that a mooring line is taken in by a drum in an even, symmetrical pattern rather than piling up on only one side or in the centre, it is particularly important that this is done with non-split drum winches. Layers of mooring line on drum

Brake holding capacity

1

100%

55 tonnes (approximately)

2

88%

48 tonnes

3

80%

44 tonnes

4

73%

40 tonnes

5

67%

37 tonnes

6

61%

34 tonnes

Table 2: Typical loss of brake holding power for each equal layer of mooring line on a drum If it is not already known, crewmembers should always check the manufacturer’s instructions or the vessel’s operating manuals to determine the winch’s brake holding capacity and the line layer it applies to (if the line layer is not specified then it should be assumed it refers to the first layer). Split-drum winches Split drum winches help reduce crushing damage to mooring lines and so are mostly used with steel wire mooring lines. The brake holding power for split drum winches always refers to a single layer of wire mooring line on the tension drum. To maintain the maximum holding power of a split drum winch brake there should only be a single layer of wire or rope on the tensioning drum. This will give a constant torque and gives the best use of the winch brake’s holding power. A second layer would increase the radius at which the line would pull against the brake.

13

SAFE MOORING PROCEDURES

The use of a tensioning drum also helps to avoid crushing any lower layers of wire or rope on the storage drum. This is of special importance when using wire lines which are more susceptible to damage through crushing. Using a tensioning drum also helps to avoid rope jamming in the lower layers, which might damage the rope as well as cause a delay in the mooring operations. Reeling Reeling lines onto a drum in the wrong direction can cut its brake holding power by up to 50%. If they have not been marked by the manufacturer with the correct reeling direction, then the deck officer should clearly mark them ‘heave in’ and ‘slack out’. Winches fitted with disc brakes do not have to be marked as they cannot be reeled in the wrong direction. Where a band brake is fitted to a winch it allows the line to be pulled directly against its fixed end. Pinned end of brake band

Pay out direction

Brake tension application

Anchored end of brake

Floating end of brake

Fig. 7: The correct way of reeling a wire mooring line onto a winch drum. Wrong use of the brake A winch’s brake should only be used for stopping and holding its drum. It is not intended for use in controlling the rate at which a line is paid out or taken in. If a line has to be slacked down then the winch should be put in gear, the brake released, and then the line walked back as it comes off the drum. A line should never be slacked down just by releasing the brake alone as this means there is a lack of control on the line, and it is therefore not completely safe. For example, if there are two mooring lines running in the same direction and sharing the load, then suddenly transferring all of that load to one of the lines, which could happen if winches are not under control, might cause it to part. Using the brake by itself to pay out a mooring line also causes uneven wear on the brake band, which can contribute to it losing power later on.

SAFE MOORING PROCEDURES

14

2.4 Printed guides and electronic aids to mooring Most busy ports and terminals have their mooring arrangements and other details set out in publications such as Guide to Port Entry. As well as these aids, many vessels now have electronic chart systems, and nearly all of these will contain detailed diagrams showing port layouts, navigational aids and moorings, and other port facilities. However, caution needs to be taken when using electronic charts in approaching and entering port as their precision and detail may not be sufficiently accurate to be used as the primary means of manoeuvring the ship to its berth. CDs are increasingly available showing port layouts, navigational aids, moorings and other port facilities. Many of the world’s larger harbours and ports now also have their own websites which can provide information on port layout, directions for navigation and positions of navigational aids, Notices for Mariners, tidal information, special instructions about anchoring, and regulations concerning such matters as explosives and LPG/LNG vessels, as well as information about moorings and other port facilities. Charts showing port layouts and information about facilities and procedures are also commercially available on the websites of nautical publishers. These can be accessed from an internet-connected computer.

15

SAFE MOORING PROCEDURES

3. Safe mooring practice 3.1 Approaching the berth: risk assessment Carrying out a risk assessment of mooring at a berth is particularly important when it is the first time your vessel docks at a particular harbour or anchorage. Preparing a risk assessment encourages the officer responsible for making the mooring arrangements to make a thorough analysis of all the factors involved and helps identify the things which could go wrong. If a Pilot is being used then his advice should be sought. There are no fixed rules about how risk assessment should be done. However, in preparing an assessment the aim should be to identify: ●

hazards the vessel might encounter

●

preparations or controls needed to avoid them

●

likelihood of something going wrong with the mooring operation

●

degree of possible damage to the vessel, or danger to the mooring party

●

level of risk

●

action plan required to minimise the risks

The main factors which need to be taken into account in a risk assessment for a mooring operation include: ●

the approaches

●

water depth

●

state of tide and currents

●

other vessels moored nearby

●

the position of cranes, loading arms and other equipment on the quay

●

ship traffic

●

weather forecast

●

loading or unloading requirements

●

the ship’s schedule

●

port authority regulations and requirements

●

the vessel’s security

●

safe placement and landing of the gangway

The result of a carefully worked out risk assessment should be a well structured plan covering all stages of the mooring operation, the vessel’s subsequent activities of loading and unloading, and the vessel’s later departure.

3.2 Making ready to moor Well before the vessel approaches its berth, the deck officer in charge of mooring should have ensured that mooring lines are in good condition. This task can usually only be done in the approaches to the port or berth, since mooring lines are normally stowed away and inaccessible at sea (ideally, the lines should also be again inspected for damage once the vessel has later left its berth). SAFE MOORING PROCEDURES

16

Winch brakes or securing devices should be checked that they are in efficient operating order, and that they have a holding power of at least 60% of the breaking load of the vessel’s chosen mooring lines for the berth ahead. Any known defect in the vessel’s mooring system or limitation of mooring winch brakes should be reported to the Pilot and the Terminal before arrival so that if necessary additional precautions may be agreed. Port operators must provide linesmen to assist with all berth movements. The vessel’s crewmembers and port personnel must not jump between the vessel and the quay to moor or unmoor their vessel. Should there be a delay in the arrival of linesmen, the Master should advise the provider of the service. A Master is entitled to refuse to moor or unmoor if linesmen are requested and are not available. The port authority should have the vessel’s berthing movements planned in advance. Prior to the vessel’s arrival in port, the Master should seek to confirm berthing arrangements with the port authority or Pilot, as appropriate. The Master remains at all times responsible for the safety of his vessel and crew and has the right to refuse to berth in any location which he feels may place either his vessel or crew in danger. A mooring party’s first task is usually to lay the messenger lines and the first ashore lines out on deck. Next, the winch covers have to be removed so that the lines can be inspected and, if instructed, made ready to have nylon tails fitted to them. The deck officer in charge of the mooring party should have a checklist of items to tick off as he goes along to ensure that everything is ready and that all the necessary standard precautions have been taken. A general pre-mooring checklist could contain items such as: Mooring checklist

Yes

No

Mooring lines in good condition Mooring lines flaked out neatly to minimise tripping hazard Mooring lines correctly spooled on drums (pulling against fixed pin of brake) Spare mooring ropes available Fairleads, rollers, bitts and chocks in satisfactory condition Deadmen and roller fairleads well greased and free to turn with little sign of grooving Brake linings and pins appear in good condition Winch seatings and connections to deck sound Anchor chain stoppers in good condition and effective Anchors cleared and ready for immediate use (except while alongside, when the locking bar should be in place)

17

SAFE MOORING PROCEDURES

As the vessel approaches the port or anchorage, the Pilot will come aboard. He and the Master will discuss such matters as the use of tugs and the mooring arrangements at the vessel’s assigned berth. Sometimes the Pilot might suggest using extra mooring lines if the weather, currents or other conditions suggest it might be safer. It is the Master’s responsibility, in consultation with the Pilot, to select the appropriate combination of mooring lines for the berth the vessel will be using, usually based on the customary arrangement of three headlines, two breast lines and a spring line. It is also the Master’s responsibility to ensure that there is sufficient water under the vessel’s keel at all times. The port or terminal authority should be able to provide the necessary information about water depth, quays and other details. It is the responsibility of the Master, or sometimes the deck officer in charge, as to how, when and in what order the mooring lines should be put ashore and this should be advised to the mooring stations prior to arrival at the berth to allow adequate planning. Communications Vessels should endeavour to maintain a listening watch on the nominated VHF/UHF channel.

3.3 Mooring, tying up and keeping station During berthing and unberthing procedures, there should always be enough deckhands in the mooring parties stationed at each end of the vessel, with an officer in charge of each group. Prior to proceeding to stations, the officer in charge should go on to the bridge to discuss the mooring plan with the Master and the Pilot, if he is there. The plan should include where he intends to take tugs, his line plan at the berth, and the sequence of running lines. As the vessel approaches its berth, the officers in charge of the mooring parties will take up their positions - from where they can see as much of the mooring deck areas and as many members of the mooring parties as possible. Although they will be supervising the mooring parties and the mooring operations, they should not actively take part in the process. Each member of the mooring party should know what his specific duties are. The deck areas where mooring operations are taking place should be off-limits to all other crewmembers not engaged in line handling activities. Areas of deck where mooring operations are taking place should be kept free of clutter or any loose tools or pieces of equipment. The vessel’s heaving line should be constructed with a ‘monkey’s fist’ at the heaving end. This should only be made of rope and not contain any additional weighting material which might injure a stevedore as it is thrown ashore. Ropes and wires which are stowed on reels should not be used directly from stowage, but should instead be run off and flaked out on deck in a open and safe manner, ensuring there is enough slack to meet any unexpected circumstances. If there is any uncertainty as to how much rope might be needed, then the whole reel should be run off. Where moorings are to be heaved on a drum end, there should be one crewmember stationed by it, supported by another crewmember backing and coiling down the slack. Three turns on SAFE MOORING PROCEDURES

18

the drum end are enough to complete the task. A wire on a drum end should never be used as a check wire. The officer in charge of the first line ashore must make sure that it does not take the full weight of the vessel if it has too much head or astern way on. First Line Ashore Today, most vessels will use a synthetic rope as their first line ashore because its lightness of weight and buoyancy makes it easier to handle for both the vessel’s mooring party and the quayside mooring team. However, its subsequent use as part of the vessel’s overall mooring system will depend on the other types of lines being used in the system.

Tying up Mooring lines leading in the same direction of restraint should be of similar material and construction throughout their lengths from the jetty’s mooring points to the vessel’s securing points. Particular care should be taken to ensure sufficient transverse restraint from breast moorings. Mooring proceeds in a predetermined order which will have been agreed between the Master and pilot, usually in the sequence of spring lines, breast lines, headlines and stern lines. Make sure that a steel wire line is never led across a fibre rope on a bollard. As with the use of the vessel’s fairleads, wires and ropes must always use different bollards or parts of the vessel’s superstructure. Keeping station As soon as the vessel is secured, brakes on all mooring winches should be firmly applied. Full pressure or power to all mooring winches should be maintained at all times when alongside. On split drum mooring winches, only one layer of rope should be permitted on the working half of the drum. An efficient watch must be maintained on the vessel’s mooring lines at all times to ensure the lines are properly tensioned and adjusted when required. The deck watch should make regular checks that mooring winch brakes are applied at the correct setting, and that self-tensioning winches are correctly set and functioning properly. Ultimately, however, it is the Master’s responsibility to ensure that his vessel remains securely moored at all times. Using the mooring lines to warp or check the vessel has to be done with care, and the mooring party should stay clear of the lines if this is being done.

19

SAFE MOORING PROCEDURES

3.4 Handling mooring lines Personal Protective Equipment (PPE) should be worn by the mooring party during berthing operations, including: ● overalls ●

safety boots with slip resistant soles

●

gloves

●

safety helmets complete with chinstraps

●

high visibility garments

●

suitable wet and cold weather clothing

Lifting lines If there are enough crewmembers to help, it is best to lift a line and carry it across the deck (although if a line is too heavy for the mooring party to lift, then it may be dragged). Dragging a line across the deck can cause it to suffer abrasion and damage, especially from rough or sharp edges. Also, dirt or grit can be picked up and can work their way into the strands of the line and cut the inside fibres. Health check for wire lines Before being used, a wire mooring line should always be carefully examined for broken strands of wire, sometimes referred to as ‘snags’. The more snags there are then the weaker the cable. If you think a line has a lot of snags, report it immediately to an officer. He can then consult the manufacturer’s specifications to see if it should be scrapped. Examination of the line should always take place in good time to allow it to be replaced if necessary well before it has to be used for berthing. If rust is spotted on a wire then this should be removed using a wire brush. Good wire handling practice ● never allow the wire to cross over its lower layer on a drum at an angle. It damages the wire and weakens the line ●

never kink the wire. It opens the lay and weakens the line

●

never open a new coil of line without using a turntable or something similar. Without it, the line can kink and become damaged.

Fig. 8: Use a turntable or similar device when unrolling a new coil of wire mooring line in order to avoid kinks occurring. SAFE MOORING PROCEDURES

20

Handling of synthetic fibre lines Always wear the appropriate safety personal protective equipment (PPE), including gloves and hard hat, when handling synthetic mooring lines, especially those which will be put under load. When making synthetic fibre lines fast to bitts, do not use a ‘figure of 8’ arrangement by itself to turn them up, but instead put on two round turns around the leading post (or around both posts if they are small) then put on your figure of 8 to make it secure.

Fig. 9: Using round turns before making a ‘figure of eight’ when fastening a synthetic mooring line to bitts makes the line safer and easier to handle.

A synthetic mooring line should only be attached to another line using a shackle or some other sort of other approved connection of sufficient strength. All mooring lines should come with a manufacturer’s certificate giving its MBL (Minimum Breaking Load). These should be kept and the ropes marked with an identifying number so that their MBL and period in service can be checked at any time. Synthetic lines should not be surged from drum ends or bitts as the heat caused by the friction can melt them. Also, synthetic lines should not be run through leads which are off at an angle from the drum, as this can cause the line to chafe and damage. Make sure that all fairleads and warping drums are free from rust, dents or jagged edges, as these could damage the lines. Make sure that roller heads are always well lubricated. When a line might suddenly snap It is important to be able to recognise when a line is getting near to snapping, or to recognise when a sudden change in weather or other changes in circumstances may be placing a strain on a mooring line which it will be unable to hold. Some day a mariner’s life – maybe even your own – might depend on that knowledge. When a new wire line is first used and a load placed on it, a small amount of stretch will take place on the line. This is because all its component wires will be ‘bedding down’, as they are forced by the pressure of the new load to squeeze into a tighter formation round each other. This is known as ‘constructional’ stretch, and it is permanent – the line will always keep that extra piece of stretched length. 21

SAFE MOORING PROCEDURES

During later use with other loads, when the wire line is subjected to loads up to 65% of its manufacturer’s stated MBL, it will experience yet more stretching but, on these occasions, once the load is removed the line will usually shrink back to its normal length. However, if the line is used to hold a load of over 65% of its recommended MBL, then there is an increased danger that a sudden moment of stretch could result in the line parting. Many mariners have been killed or badly maimed by snapped and whiplashing lines in such circumstances.

●

Be aware of load weights on lines at all times – and know their critical danger breaking points.

Typical Line Breaking Points 180 kg wire lines 28mm 32mm 36mm 38mm 40mm 44mm

(6 (6 (6 (6 (6 (6

x x x x x x

36) 36) 36) 36) 36) 41)

Typical breaking load with fibre core

Typical breaking load with wire core

46.6 tonnes 60.8 tonnes 77 tonnes 85.7 tonnes 95 tonnes 115 tonnes

50.3 tonnes 65.7 tonnes 83.2 tonnes 92.6 tonnes 103 tonnes 124 tonnes

Table 3: Typical breaking loads for different diameters of round strand, Equal Lay, wire mooring lines

SAFE MOORING PROCEDURES

22

Rules of Line Safety Always, always…. ●

Wear protective safety gear when handling lines

●

Keep clear of any bight in a line. If it suddenly tightens you could be caught and killed

●

Stand well clear of a taut line under load

●

Try to keep in control of a line

●

Try to make sure the line is properly secured so as to prevent its loss

●

Try to anticipate any situation which may cause a line to run out of control

●

Never try to catch a runaway line by grabbing it with your hands or by stepping on it

●

Keep well clear of any whiplash/snapback zones

Never, never…. ●

never pay out a synthetic fibre line on the drum end, as this can cause it to heat up and melt and may then stick dangerously to the drum or bitt. Always walk a winch back to take the weight off the line

●

never stand close to a winch drum or bitt when holding a synthetic line as you may get pulled into it if the line jumps. Always stand at least one metre away

●

never apply too many turns to the line as it makes it difficult to let go easily. Three turns are enough with any synthetic line

●

never bend the line too much

●

never stand in the bight of a line

●

never stand too close to a line under load in case it parts

●

never leave tools or other objects lying around on the deck near a line under load, as it may send them flying if it parts and catches them

●

never allow more of the mooring party than is necessary to stand near a line under load

Whiplash, or snapback: when a line can strike faster than a cobra! When a synthetic line parts it can do so with virtually NO WARNING. This whiplash, or snapback, effect has been the cause of many fatal accidents, and the possibility of it happening on board your vessel has to be taken very seriously. When a line is under load it stretches, causing high levels of energy to build up in it. The longer the length of the line being stretched and the bigger the weight of the load it is holding, then the greater will be the amount of energy building up. With synthetic fibre lines being able to stretch much more than steel wire lines, the danger of whiplash is therefore much greater, and the energy force it can then release on parting can also be so much greater – and therefore much more deadly. Unlike a wire line, which can sometimes give a warning by making a ‘singing’ noise when under extreme load and experiencing extreme tension or stress, a damaged or overloaded synthetic fibre line about to snap may not give any advance warning sounds or indications that it is about to part. The first indication may be the sudden loud crack as it parts. To help this situation, some synthetic fibre lines now have a brightly coloured strand woven into them which are designed to be a ‘first to go’ early warning indication of a line being in imminent danger of parting. 23

SAFE MOORING PROCEDURES

Danger zones To avoid the danger of whiplash, or snapback, crewmembers in the mooring party should stand well away from the likely path of a parting line. This can be the immediate area around the line’s path, as well as across a wide area behind points such as fairleads, or where the line has been secured or looped around. All of these can be danger zones in which the remainder of the line can instantly and dangerously whiplash back along its entire length.

Point of Break

Snapback Danger Zone Point of Restraint

Fig. 10(a): Where a mooring line is running directly from the winch to a bollard through a fairlead directly ahead of the winch, the snapback area where the parted line might whiplash forms a narrow cone, the length of which will depend on where the line parted.

Point of Break Fairlead

Snapback Danger Zone

Point of Restraint

Fig. 10(b): Where a mooring line has been run around a fairlead or any other piece of deck gear the snapback area where a parted line might whiplash is more difficult to predict, and will depend on the angle of the line and where it parts. Since it is impossible to predict exactly when a line will part, or at which point along its length it will break, it can be difficult to mark out a precise danger zone. However, you can estimate what areas of the deck could be in that danger zone and ensure that as few crewmembers are in that area for as little time as possible. Other precautions you can take include planning a safe approach to a mooring line, and doing whatever work is necessary when the line is slack or has only a little tension on it. Otherwise, stand well away whenever possible from a line under tension. And never, never try to test the tension on a line by standing on it or by kicking it – this is a very stupid practice, and very dangerous! SAFE MOORING PROCEDURES

24

Performance and characteristics of mooring lines The widely varying performance and characteristics of the many different types of wire and synthetic mooring lines are detailed in Appendix 2 at the end of this Guidebook.

Line handling on a passenger ships Handling mooring lines on passenger ships can have added difficulties. Mooring duties are usually carried out in a small and very confined deck area specially set aside. In a more open area of deck, a line which has parted and is whiplashing usually tends to fly up and over; however, in an enclosed areas, a parted line can easily fly up and hit an overhead deck, so making its course much more unpredictable and dangerous.

3.5 Winches Correct use of winches A winch’s brake should be used only for stopping and holding its drum. It is not intended for use in controlling the rate at which a line is paid out or taken in. If a line has to be slacked down then the winch should be put in gear, the brake released, and then the line walked back as it comes off the drum. A line should never be slacked down just by releasing the brake alone, as this means there is a lack of control on the line, and it is therefore not completely safe. For example, if there are two mooring lines running in the same direction and sharing the load, then suddenly transferring all of that load to one of the lines, which could happen if winches are not under control, might cause it to part. Using the brake by itself to pay out a mooring line also causes uneven wear on the brake band, which can contribute to it losing power later on.

●

Basic winch safety deck working areas around winches should be painted with a non-slip type of paint

●

make sure the winch operator can see the officer in charge at all times

●

never leave a winch running without an operator being at the controls

●

never lash a winch’s or capstan’s controls in the ‘on’ position

●

never stand on the winch to get a better view

●

never try to clear any obstructions on the drum without first shutting down the winch

●

when using a double barrel winch make sure the drum not in use is clear, or out of gear

●

never handle a line on a drum end unless there is another crewmember there to remove or feed the slack to you

●

never work too close to drum when handling a line as it could suddenly run in faster and trap your hand

●

if any shield covers are missing from protecting moving parts get them replaced

●

always wear your PPE at mooring stations

3.6 Windlasses, chains and anchors Your vessel will have a set procedure for anchoring, and you should read and understand this procedure. 25

SAFE MOORING PROCEDURES

General anchoring and weighing anchor procedure Before an anchor is used, a competent deckhand must check the brake of the windlass to ensure it is on, and then clear away voyage securing devices. Whenever possible, the anchoring party should stand aft of the windlass. All should be wearing PPE, including safety glasses. Whoever is in charge of anchoring operations must make sure that the bridge is kept constantly informed about what is happening, what is about to happen, and any other appropriate information. During the anchoring procedure a sharp lookout should be kept to ensure no small boats or tugs are in the vicinity of the anchor dropping point. This is especially necessary before the anchor is let go. If the anchor is being let go from the stowed position and then fails to run when the brake is released, do not attempt to shake the cable to try to release it. Instead, apply the brake, put the windlass in gear, and then walk out the anchor before letting it go. On weighing anchor the cable should stow automatically, and while it is doing so nobody should go into the cable locker. Anchors housed and not needed should be properly secured to prevent accidental release. Avoiding anchor loss Where anchors have been lost this has usually been due to either the vessel still going too fast when dropping anchor, or not enough anchor cable having been paid out at the start before finally letting go. To minimise the chance of losing an anchor and its cable, the deck officer in charge of the procedure should reduce the vessel’s speed to either dead stop or slightly astern before letting go. In deep water an anchor can also be further protected from loss by being ‘walked out’, which means running it out with the windlass kept in gear, which helps provide greater control of the anchor’s movement. For very large vessels with heavy anchors and cables, the anchor should be walked all the way out to avoid excessive strain on the brakes (and on the bitter end if the brakes fail to stop the anchor and chain). Keeping the windlass in gear and if possible fitted with a speed limiter, not only gives more control, it also helps reduce wear on the brake lining. It should be taken out of gear and the brake applied in order to bring the vessel up. Anchor chains, or cables Even when your vessel is equipped with a cable counter it is still recommended that your anchor chains or cables be brightly marked in lengths, such as with white paint or with regularly spaced stainless steel bands. It is also recommended that the second shackle from the bitter end is painted red, or marked in some other way. Windlass brakes Windlass brakes are at their strongest when tightened up as soon as the maximum weight comes on the anchor cable. It should not then be necessary to make any other adjustment to the brake, since any change in the load caused by the tide or wind can be taken by the cable stopper.

SAFE MOORING PROCEDURES

26

Cable stoppers Cable stoppers are an important part of the anchor cable’s restraining equipment and are intended to take the anchoring load. They must always be used whenever the vessel is at anchor. Stoppers should be put on the cable, along with its securing chains, once the anchor is home and secure. Stoppers should only be used after the windlass brake has been set, so that the brake provides extra holding power to the stopper.

Fig. 11: Anchor cable stoppers must be applied after the windlass brake has been set. When a stopper is being used with a particularly heavy load then it may be necessary to tie it down in order to prevent it jumping. Stoppers should also be put on the cable once it is home and secure. Mooring line systems

3.7 The ideal mooring line system The experienced mariner will know that factors like the speed and direction of the wind and currents can unexpectedly change, and that vigilance is needed at all times to make suitable adjustments to the mooring arrangements. Nevertheless, Figure 12 shown below sets out an efficient mooring system suitable for meeting the stresses and strains placed on mooring lines by the forces of wind, tide and currents, whether meeting the ship transversally (beam on) or longitudinally (from the direction of the bow or stern). After Breast Lines

Stern Lines

Breasting Dolphins

Walkways

Head Line Spring Lines

Forward Breast Lines

CL

Fig. 12: A typical mooring arrangement designed to meet the forces of winds and currents. 27

SAFE MOORING PROCEDURES

Which lines matter most? In safely securing your vessel to a mooring, all lines can play an important part. However, experience has shown that in certain circumstances some lines can take a greater share of the vessel’s load. The most commonly used mooring system uses spring lines, fore and aft, breast lines, fore and aft, and head and stern lines. In nearly all cases it is recommended that: ●

breast lines act as your vessel’s main safeguard against transverse forces pushing it off its berth, and should be as long as possible

●

spring lines act as the main counterbalance to longitudinal forces

●

short lines should be used with caution, as they take a disproportionate share of the strain, and can also be more adversely affected by tidal forces.

●

Head lines and stern lines prevent the ship from yawing.

Ideally, wire cables or high modulus synthetic ropes should be used for spring lines and conventional synthetic fibre ropes used for head lines, breast lines and stern lines. Nevertheless, it should be noted that these are not rules that must be applied in every mooring situation. In some situations a long headline and a long stern line can assist with the vessel’s safe longitudinal movement nearly as much as spring lines. Similarly, it could sometimes be argued that a stern breast line from the offshore quarter is better than a near side quarter line. The way to successful mooring is through understanding the dynamic forces operating on your vessel while it is moored, and understanding the efficiencies of different mooring systems and different configurations of lines. Not every line pulls its equal weight In the example shown (Figure 13), a moored vessel’s head lines, positioned at 45º to the breast lines, usually contribute up to 40% of the mooring system’s restraining power to hold the ship in position, while the vessel’s breast lines and spring lines together provide the other 60% of the holding power.

Tranverse force

Fig. 13: In an extreme mooring situation, such as when the vessel is riding high and there are both a wind and a current meeting it beam on, these will usually produce a force occurring within a 25º angle to the beam, and so more aligned to the ship’s breast and spring lines. But even if the wind and current did align more directly with the head line, that line would still only provide less than half the total restraining force on the ship, while the breast and spring lines together would be providing well over half the total restraining power securely gripping the ship. SAFE MOORING PROCEDURES

28

3.8 Stoppers Stoppers for wire lines Stoppering a steel wire before turning it up on the bitts can be done either by using a specially made stopper, such as the carpenter stopper shown in Fig.15, or if this is not available, then by using a length of chain instead. Rope should never be used as a stopper as it does not have enough grip on the wire line.

Fig. 14: Carpenter stopper When using a carpenter stopper it should have the same breaking load as the wire line on which it is being used. A good safety benefit of this type of stopper is that it is self-tightening and can be left in position unattended. Also, so long as it is the right size and design for the thickness and lay of the line on which it is being used, it will not damage it. Carpenter stoppers are normally available for lines up to 20mm diameter, but lines bigger than that become difficult to handle. Chain stoppers come in different sizes and grades, and crewmembers should become familiar with what is used on their vessel. They should know: ●

size; the diameter of the chain link

●

type; whether close link chain, its grade of tensile steel (high grade, used on most vessels, is around 63 kg/mm2, although even tougher grades with higher breaking loads are also used on some bigger vessels in certain circumstances)

●

length; usually 4–5 metres.

Secured end

Free end

Fig. 15(a): Cow-hitched chain stopper. If a chain stopper has to be used, then it must only be attached to the mooring line using a cow hitch, sometimes known as a lanyard hitch, and never by using a clove hitch, which is not sufficiently secure and can slip.

29

SAFE MOORING PROCEDURES

Fig. 15(b): A chain stopper should never be attached to a mooring line using a clove hitch knot, but instead use a cow hitch knot. During every refit it is important that a ship’s chain stopper should always be tested for defects and re-tempered, and that a record of this procedure is kept.

Chain size

Typical breaking load

12mm

7.2 tonnes

16mm

12.7 tonnes

20mm

19.9 tonnes

Table 4: Breaking loads for different sizes of high tensile steel chain stoppers, which are usually less than the breaking loads than the mooring lines on which they are attached. Giving steel wire cables some elasticity when necessary It can be helpful in some circumstances for steel cables to be given some extra, temporary, elasticity - for example, when there is the risk of the vessel being subject to heavy swell or strong currents, or of being buffeted by strong surge from passing vessels. In such situations some elasticity on the steel cable can help reduce the sudden impact and extra strain on the cable and the ship, which could possibly result in the cable parting. Elasticity can be temporarily added to a wire cable by joining a nylon or other conventional synthetic fibre rope ‘tail’ to it. This should be done by using a special stainless steel shackle designed especially for the purpose, so as to avoid wear on the wire cable. Preferably, Mandel or Tonsberg-type shackles should be used. An ordinary D or bow shackles must not be used if it can be avoided, as they are not designed for this purpose and can soon cause damage to both the wire cable and nylon tail.

Fig. 16: Stainless steel shackle used to attach a nylon tail to a wire mooring cable

SAFE MOORING PROCEDURES

30

A temporary tail should not be more than 11 metres in length in order to avoid the wire cable being given too much elasticity, as this could contribute even more strain on the wire cable. The eyes of the tail should be sheathed in a leather or plastic glove to protect them from chafing. Synthetic tails lose strength more rapidly than steel wire, so all such tails, other than those made of nylon, should be of a minimum breaking strength 25% greater than the MBL of the wire cable to which they are attached. A nylon tail, however, which loses strength even more rapidly than other synthetic fibres, should be of a strength 37% greater than the wire cable to which it is attached. All parts of this type of arrangement – the nylon or other synthetic tail, the wire cable and the connecting shackle – should be inspected frequently for signs of wear. Stoppers for synthetic lines Different types of synthetic fibre lines need the right type of rope stopper. Fibre stoppers should be used on the double and, where possible, should be of the same type of material as the line on which they are being used. Ideally, the stopper should: ● be flexible ●

as narrow in diameter as possible

●

have minimum possible stretch

●

maximum possible melting point

●

have a combined strength of at least 50% of the MBL of the line on which it is being used.

Fig. 17: The correct way of stoppering off a synthetic mooring line.

3.9 Emergency action Sudden and unexpected changes in load (see ‘Forces and factors affecting mooring’, page 4) can sometimes cause a winch’s brake to slip and pay the line out, resulting in the vessel drifting off its berth. If a sudden increase in line load did cause a winch’s brake to slip, the winch will not have the power to heave in (see earlier section on ‘brake holding power’). If the vessel is drifting off its mooring, the OOW or the Master must be alerted immediately. They must be quickly told of the cause of the drifting. They will then decide what action to take. The principles for alerting others to a mooring emergency are the same as for other types of emergency:

31

SAFE MOORING PROCEDURES

●

make a quick and accurate assessment of the situation

●

alert the Master or OOW

●

communicate the situation clearly

●

start working to the pre-planned procedure for dealing with the situation (your vessel should have an emergency procedure already in place for dealing with this sort of situation, as it should for all other types of emergencies).

Do you know…? An officer supervising mooring duties should know: ● the size, length and type of all the mooring lines, along with their age and condition ●

the heaving power and render value of each mooring winch

●

their type of brake and its holding power at which layer

●

if the render value and holding power together of each winch is higher than its line’s MBL (making a reduction of 20% to allow for wear and tear).

Special or hazardous conditions

3.10 Bad weather operations Mooring at below zero temperatures Extreme cold causes seawater to freeze at around –1.5º C, although the exact freezing point depends on how salty the water is. When ice forms on a vessel it can burst pipes, immobilise moving parts of machinery, and make equipment difficult to handle. If a vessel has been icedup and will soon be berthing then steps need to be taken to prepare it for mooring while it is approaching port (see also the Videotel training programme The Cold and Heavy Weather File). Ice Blue ice and anti-skid paint should have already been put down on the focsle, poop deck and other mooring areas if a forecast of sub-zero temperatures has been received by the vessel, and this should help prevent the formation of ice or make it easier to remove any that has already formed. Anchors Anchors must be kept free of ice, which can either be chipped off or broken off through a process of alternately heaving them in and walking them back. Lines Except for those already wound on a winch, mooring lines should be kept stored below deck, then brought out just before berthing to be flaked on wooden gratings and covered with tarpaulins until needed for use in mooring operations. Even so, lines kept like this may still become so stiff in the sub-zero temperatures that they are difficult to manhandle or to wind around a winch drum. Spare, pliable lines should be kept ready below decks in anticipation of such difficulties. When paying out a line it should make as little contact with the water as possible to avoid it freezing up and becoming stiff and difficult to work. During iced-up conditions it is better to keep the lines as taut as possible to prevent the vessel falling off and allowing ice to form between the ship and the quayside. SAFE MOORING PROCEDURES

32

Winches and windlasses On the first warning of sub-zero conditions, a thick layer of grease mixed with some antifreeze solution should be applied to all moving parts on winches and windlasses. Oil, hydraulic and electrically-driven systems may need to be kept on regular periods of slow turning to keep them free from ice. Mooring party and deck conditions When engaged in mooring operations, the wind chill factor will affect the air temperature, making it considerably colder and therefore more difficult for crewmembers to carry out their duties. When mooring and departing crewmembers should stay out of the wind for as long as possible. Wind chill temperatures Wind speed (knots)

Actual air temperature (ºC) 9

-4

-8

-12

-16

-20

Temperature including windchill factor (ºC) 3 5 11 16 22 27 32 38 43 49 54

0 -4 -10 -14 -17 -18 -19 -20 -21 -21 -21

-4 -8 -15 -20 -23 -25 -26 -27 -27 -27 -27

-8 -13 -21 -25 -29 -31 -32 -33 -34 -34 -34

-12 -17 -26 -31 -35 -37 -39 -40 -40 -40 -40

-16 -22 -31 -37 -41 -43 -45 -48 -47 -47 -47

-20 -26 -36 -43 -47 -49 -51 -52 -53 -53 53

Table 5: The shaded area shows where a crewmember’s exposed skin can freeze within just 60 seconds, even quicker if he touches frozen metal Preparing mooring equipment in sub-zero conditions Action

Equipment

Responsibility

Protect with grease

Anchor stoppers Riggings Engaging gears Clutches Windlasses

Bosun

Protect with covers

Control boxes Motion levers Mooring lines

Chief Officer

Protect with low temperature oil

Hydraulic systems

Chief Engineer

Heating fuel oil

Bunkers, double-bottomed tanks, steam driven systems

Chief Engineer

33

SAFE MOORING PROCEDURES

Maintain circulation by keeping running on slow turning

Hydraulic systems Steam driven systems

Chief Engineer

Drain off any water and keep empty before entering iced waters

Chain lockers

Chief Officer

Clear ice accumulation to prevent build up of ice and slipping. Apply blue salt

Deck

Chief Officer

Clear ice accumulation

Anchors

Bosun

Keep under cover until needed and have spares available in case of freezing

Lines

Bosun

Drain or stopcock or blank the water inlet

Water cooled mooring systems Hydraulic system cooler

Chief Engineer

Table 6: Preparations and precautions to be taken when preparing to moor in foul conditions Mooring in poor visibility Whether because of fog or snow, if visibility is poor when you are about to enter a port with which you are not familiar there are several choices: ●

anchor outside the port in a safe place until visibility improves

●

request a Pilot

●

request tug assistance

●

proceed to the berth anyway, relying on your radar, electronic charts and lookouts

Although the final decision as to which of these options to select is the Master’s, it will probably be necessary to consult with the port authority, as the vessel’s allocated berth might only be reserved for a limited period. Mooring arrangements in a high security risk port There are many concerns about terrorism and also the increasing numbers of people who are seeking to leave their native lands, often by stowing away on vessels known to be heading for more attractive countries. So before entering a port where there may be a security risk, you may need to do a special risk assessment and some extra pre-planning of your mooring arrangements. This will ensure your security and to prevent unauthorised people climbing aboard by using the ship’s mooring lines (see the Videotel training programme Coping with Stowaways, which describes precautions which can be put in place) and to prevent unauthorised goods being placed aboard.

SAFE MOORING PROCEDURES

34

3.11 Mooring at buoys Mooring at buoys is a highly specialised procedure, and there is another Videotel training programme which goes into more detail on the complexities of the subject (entitled Mooring at Buoys). Nevertheless, there are some basic procedures and precautions which illustrate how this procedure is different to mooring at a quay. When slip wires are to be used for mooring to buoys or dolphins, the eyes of the wires should never be put over the bitts, because when it comes to slipping the mooring it may not be possible to slacken the load sufficiently to lift the eye clear. To prevent accidental slippage of the wire eyes over the bitts or other obstruction the eyes should be sized, partially closing the eye. Conventional or multi-buoy moorings (CBM or MBM) Although mooring at a CBM or MBM is not a precise science and there are several different ways to successfully do it, Fig 16 below shows the standard, generally-accepted method of doing so, using both forward anchors and with the stern secured to an arc of buoys with several mooring lines. This arrangement can take considerable skill, a lot of time and much manoeuvring to successfully carry it out.

Fig. 16: Setting up such a mooring arrangement using buoys and anchors and without the assistance of tugs will often require the use of nearly all the ship’s mooring equipment To set up this mooring arrangement, the vessel begins with what is known as a ‘running moor’. This manoeuvre is usually started with the buoys to which the vessel is going to be made fast lying to its port. This positioning enables the vessel to get maximum manoeuvring benefit from its anchors once they are dropped during the manoeuvre. Nevertheless, the running moor manoeuvre can still be carried out if the vessel starts off with the buoys to starboard.

35

SAFE MOORING PROCEDURES

The running moor

E D

C Hose

B

Y

C

A

Fig.17: The running moor procedure The vessel moves slowly towards the forward end of what will be her final berthed position, and at an angle of nearly 90º to what will be its final moored position Fig 17 (a) At the right moment the starboard anchor is let go and the cable run out, while the vessel continues to move ahead. Again at the right moment the engines are put astern and the rudder put hard to port Fig 17 (b) By careful manoeuvring, using the engines and helm, the vessel will aim to line up its stern approximately with the middle of the group of buoys. Once it has achieved a satisfactory position, the vessel lets go its port anchor and stops engines Fig 17 (c) Now, by a skilful combination of paying out and taking in the anchor cables, while at the same time using its helm and engines in forward and astern, the vessel can then manoeuvre itself towards its intended final berthing position. Fig 17 (d) Once roughly in its intended berthing position, the engines are cut, the anchor cables made fast, and mooring lines are quickly run out to each of the buoys where once fastened they can be used to help position the vessel exactly where intended, and all lines are then made fast. Fig 17 (e) Advance preparation pays off The success of the running moor procedure greatly depends on dropping the first anchor in exactly the right spot. If that first anchor misses it mark and is dropped too far away, it is almost impossible to successfully complete the rest of the manoeuvre and the vessel will have to heave up and start all over again. To avoid this possibility it can be helpful if the vessel’s approach course to the dropping point, as well as the dropping point itself, are both marked by leading lines or ranges.

SAFE MOORING PROCEDURES

36

During the running moor manoeuvre, the mooring lines being used will experience far greater loading than in normal mooring procedures, so it is recommended that only lines on drums are used while it is in progress. Before embarking on such a complicated manoeuvre it is also recommended that all winches and lines be carefully checked that they are in good order. Safety check The running moor procedure also requires considerable moving about around the deck by those crewmembers taking part in its operation, so it is best if other crewmembers are kept off deck to prevent them getting in the way at a difficult moment. Finally, this mooring procedure should be done under the supervision of an experienced officer, using crewmembers experienced in mooring duties. The officer should carefully brief those crewmembers taking part beforehand about the different stages in the procedure and the responsibilities each person will have. Where there is restricted searoom for manoeuvring, some terminals may provide their own mooring team to perform the operation. At many CBMs, a vessel’s own moorings are often supported by shore wires run from the buoys or from the sub-sea platforms. It generally needs experienced seamen to be able to manhandle these heavy wires around a warping drum of a winch and from there to the bitts. When stopping off the wires before securing them to the bitts, carpenters stoppers of an appropriate size should be used. Performing a running moor operation means that there will often be mooring boats at the vessel’s stern and when there are lines in the sea. It is therefore very important to have constant communication between a lookout stationed at the stern, the officer in charge of the operation, and the bridge in order to ensure neither boats nor lines get caught up in the propellers during all the manoeuvring taking place. Unmooring When the vessel is unmooring, the shore wires need to be stoppered off with the carpenter’s stopper, transferred to the winch drum and then walked back, using slip wires if necessary. No full length wire should ever be let go ‘on the run’ as it could whiplash and injure someone. As the anchors are weighed and all the lines heaved in the vessel will then move forward to clear the buoys. The windward mooring line is usually the last to be let go so as to prevent the stern swinging on to the lee buoys. Whatever the type of berth a vessel is moving away from, special vigilance must always be kept to ensure that the stern lines are always kept clear of the propeller. It is easy for the officer in charge of the mooring party or the crewmembers responsible for handling the stern lines to fail to keep their attention on where the line is in the water. Allowing a line to foul the propeller can have serious consequences for the ship’s schedule.

37

SAFE MOORING PROCEDURES

Single buoy mooring (SBM) SBM equipment When tying up to a Single Buoy Mooring (SBM), the vessel’s bow is usually secured to the buoy with two special lines attached to a swivel on the buoy. This swivel mechanism allows the vessel to freely swing around the buoy as the wind or tide might take her. Chain support buoy Mooring assemblies

Pedestal fairlead Buoy tanker Fairlead Stopper or Smit bracket Floating hose strings Launch Pick-up arrangement

Fig. 18: Single buoy mooring arrangements need special lines and equipment which are normally provided by the terminal or port authority As the vessel is only moored at one point on her structure all her load, plus the considerable extra forces added through the movements made by the action of the wind, tide and currents, is taken up by that pair of special lines. These, therefore, are always supplied by the terminal authorities, and both are usually 120 - 190mm diameter and made from either nylon or polyester, giving each an especially high MBL. Single buoy mooring line Minimum Breaking Loads Line diameter

Nylon

Polyester

120mm 168mm 192mm

305 tonnes 570 tonnes 760 tonnes

219 tonnes 430 tonnes 550 tonnes

Table 7: Few vessels will normally carry lines of this size and strength, and they are usually provided by a terminal authority to be specially used for a SBM arrangement.

SAFE MOORING PROCEDURES

38

In a SBM arrangement, the vessel tends to swing around far more than when conventionally moored. This extreme swinging can cause the mooring lines to continuously chafe on the fairlead. To stop this happening, chafe chains are attached to the end of each mooring line and positioned through the fairleads then secured to chain stoppers or brackets (known as Smit brackets) specially attached to the focsle for this purpose. Chafe chains are normally 76mm diameter links with safe working loads (swl) of 250 tonnes, or 54mm links with 100 tonnes swl for vessels below 100,000 DWT.

Fig 19: A SBM chain stopper of the tongue type Mooring procedure Each of the SBM’s mooring lines and chains are supported by its own small buoy, while an 80mm diameter and 150 metre long polypropylene floating pick-up line is attached to the end of each chain. Before the vessel begins her run in to the buoy, a 75mm messenger line should be secured to a winch, from where a 90 metre length should be kept ready on the focsle, with the loose end having been run through the chain stopper in one of the bow fairleads. This will be used as a pick-up line to heave in the SBM’s chains and hawsers. Be prepared During such mooring operations, whether SBM or MBM, emergency equipment should always be available on deck in the event of an unexpected accident. This should include: ● large axe ●

sledgehammer

●

crow bar

●

fire extinguishers

●

spare lifejackets

The mooring operation is usually supervised by a pilot stationed on the bow along with the officer in charge of the mooring party who should be in radio communication with the bridge to pass on the pilot’s orders and other information. At no time during the operation will the vessel drop anchor, except in a great emergency, so as to avoid damaging undersea pipelines and the SBM’s own anchoring gear.

39

SAFE MOORING PROCEDURES

When the vessel closes on the SBM the messenger line is passed down to a mooring boat, whose crew will attach it the SBM’s pick-up rope. When the mooring boat is clear the pick-up line should then be winched in until the chafe chain is brought through the fairlead and then quickly secured to its stopper or bracket on the focsle. Once the chain is secured the pick-up rope should be walked back until its weight is all on the stopper r bracket While winching in the pick-up line and chain, it is important that they should always be kept slack, otherwise it can be dangerous to crewmembers if they tighten before the chain is properly secured to the stopper. Good communications between the bridge and the pilot and officer stationed in the bows and careful manoeuvring of the ship may be needed to keep the line slack until the chafe chain has been properly secured to the stopper. The pick-up line by itself should never be winched in an attempt to heave the vessel into position or to try to hold its position. Special connections If the chain is to be attached to a Smit bracket then the vessel is usually expected to have a mooring chain already connected to the bracket before it arrives at the SBM. Once the chafe chain is heaved aboard, it is then stoppered off using special chains and stoppers supplied by the terminal authority. The chafe and mooring chains should then be linked up with a special shackle supplied by the terminal. While moored Although it is not so necessary to set a watch or regular inspection on a SBM, as it can often be with a conventional mooring system’s lines, bearing in mind that the vessel is not anchored it is recommended that an experienced crewmember should be set to watch the SBM and the mooring lines, in case the vessel begins to yaw alarmingly or perhaps begins to ride up to the buoy. Unmooring Unmooring the vessel from the SBM is generally a simple process of unfastening the chains from the stoppers, walking them back to be paid out through the fairlead, and then using the pick-up rope to drop them back down to the water to be unfastened by the mooring boat. Whether unmooring from a CBM, MBM or SBM, the officer in charge, as when engaged in mooring, should again have an unmooring checklist, such as: Unmooring checklist Areas cleared for mooring lines flaked to minimise tripping hazard

Yes / No

● ●

Mooring lines correctly spooled on drums (pulling against fixed pin of brake)

●

Safety equipment available

●

Fairleads, rollers, bitts and chocks in satisfactory condition

●

Deadmen and roller fairleads well greased and free to turn with little sign of grooving

●

Brake linings and pins appear in good condition

●

Winch seatings and connections to deck sound

●

Anchor chain stoppers in good condition and effective

●

Anchors locking bar ready for immediate use

●

Ready to check mooring lines for condition once taken in

SAFE MOORING PROCEDURES

40

3.12 Tug operations and towing procedures Tugs can be in attendance when you are berthing either to act as a precautionary escort, to stand-by in case their assistance is needed, or to actively provide assistance when it is already known that it will be needed. The main purpose of an escorting tug is to assist a vessel if it meets an emergency and cannot control its own course or speed. The tug’s duty would then be to take the way off the vessel and control its course and speed. Whatever the circumstances when working with tugs during mooring operations, two factors are very important in making your procedures safe: ●

good communications with the tugs

●

understanding how tugs operate

The Pilot’s responsibilities If your vessel has taken on a Pilot it is his responsibility to advise the Master on: ● tug rendezvous position ●

number and type of tugs needed

●

towline forces that may apply

●

planned speed and route of the tow, and any hazards

●

how the towline is to be taken aboard by the crew

●

the tugs’ manoeuvres during berthing

●

emergency procedures

●

the release of the towline

●

primary and secondary VHF channels to be used for communications

If a Pilot is not involved in the tug operation then it is the responsibility of the port or terminal authority to agree these factors with the Master. Pre-planning and communications It is important that Tugmasters should be briefed in advance about the planned use of their vessel during the towing, and this should be the responsibility of the Pilot or, if there isn’t one, then the Master. The Tugmaster should then be kept fully informed while a mooring operation is in progress. It is preferable that communication between your vessel and tugs is done directly between the Master and the Tugmasters, with the deck officer in charge of the mooring gang also in communications with all those involved in the mooring operation. During tug manoeuvres events may have to happen quickly, such as perhaps the tug having to rapidly make fast with the vessel being escorted. This sort of contingency procedure needs to be agreed in advance. Poor pre-planning and poor communications between a towed vessel and its tugs have been the causes of many accidents. Towing procedures Tug towlines can kill As with mooring lines, dynamic forces occur in a towline which can become extremely dangerous. These forces are generated by actions such as the sudden accelerations of the tug, unexpected manoeuvres, wind and waves, and many other factors. Any of these, either individually or together, can create excessive load on the towline which can have dangerous, or even deadly, consequences. 41

SAFE MOORING PROCEDURES

Towline angle There is a serious danger of a tug capsizing when its towline reaches a large angle to the fore and aft line and the tug is unable to slip her tow. To reduce the danger, tugs engaged in harbour duties will usually have towing gear which is designed to minimise the prospect of overturning due to the lead of the towline, commonly referred to as ‘girding’ or ‘girting’. This may be done by fitting a permanent towing arrangement involving the use of a ‘gob’ rope. A tug’s towing hooks should have some means of quick release, which can usually be controlled from both the wheelhouse and the after deck, as well as at the hooks themselves. The towing arrangement between your vessel and the tugs should be regularly monitored during a tow, and when towing off a winch, the scope should be adjusted from time to time to avoid concentrated stresses. Towing arrangements Towing arrangements and procedures should always reduce to a minimum any danger to personnel during the operation. The design and arrangement of towing fittings should be able to cope with any emergency situations as well as normal towing conditions. Sufficient spare equipment to completely re-make the towing arrangements should always be readily to hand. Secondary or emergency towing arrangements should be fitted on board the tow so it can be recovered by the towing ship in the event of a failure of the main towing system or supporting equipment. All equipment used in a towing arrangement should have proper certification and any areas of contact between the tow line and the structures of both the tug and the towed vessel should be suitably protected. The form of towing arrangements on harbour and coastal tugs will depend mainly on the requirements of individual tug operators, but they are normally of wire rope and/or synthetic rope. Synthetic rope is most commonly used in towing due to its elasticity and its ability to absorb dynamic loads generated in harbour or coastal uses. With the different types of synthetic ropes having the markedly different properties and handling characteristics, these might affect the way a tug operates and how it reacts to different manoeuvres performed by your vessel. Breaking loads Towing standards for tugs operating in harbour and coastal areas depend on operating to Breaking Loads (BL) for towlines, which have been assessed and adjusted by different towing companies, Tugmasters, and rope manufacturers through years of experience and the requirements of particular applications. The ratio of BL to effective bollard pull (EBP) may vary between two to four times the EBP. Some operators require a towline’s BL to be six times the EBP - for example where a dynamic load on a towline may exceed the EBP. A low safety factor will adversely affect the towline life. SAFE MOORING PROCEDURES

42

Operators and tug captains will have operating experience and views on the use of stretchers in any towing arrangement. However, the inclusion of unsuitable non-approved elements, such as old vehicle tyres, should never be allowed in any towing arrangement. Tow lines Although most tugs use synthetic fibre towlines, other towlines for use in harbour can be: ●

a single steel wire

●

a steel wire towline, stretcher and steel wire pendant

●

a synthetic fibre rope towline with or without the fibre rope pendant

A spliced line should never be used as a towline. It is not recommended that a vessel’s own mooring lines be used for towing, as their strength and structure may not be able to hold the tug’s towing force, particularly the more powerful tugs used in large ports and terminals. Given that the BL of mooring lines used by a bulk carrier of 500,000 tonnes and 200,000 tonnes dwt should be about 70 tonnes and 50 tonnes respectively, and that assuming an attendant tug will have an EBP of 30 tonnes, then the BL for the tug’s towlines should be about 4 x 30 = 120 tonnes. Clearly, the mooring lines used by both those bulk carriers do not meet the required BL strength. High-modulus synthetic fibre ropes are usually used as escort towing lines. The minimum bending diameter for such ropes is normally around 10 times rope diameter for plaited lines, and 8 times for braided lines. It is generally accepted that a towline with a minimum diameter of 60 centimetres, or around 24 inches, and with a MBL of 400 tonnes is needed for an escort pull-back service. If a tug uses wire cables for towing, extra care must be taken if, for some reason, one of the towed vessel’s own synthetic fibre lines is to be used instead as the towline. The tug’s towing gear might be pitted and abrasive from previously using wire lines, which could cause the synthetic line to part. Safe handling of tug tow lines It is important that crewmembers on a towed vessel stay well clear of a tug’s towline at all times, unless the officer in charge gives a specific instruction otherwise. Crewmembers of the vessel being towed must not handle the tow line unless and until the officer in charge of the mooring party gives such an instruction. Crewmembers must never respond to any instructions from the tug’s crew, and should never let go a tug towline unless their own officer instructs them to do so. When a tug’s towline is being secured to your vessel or let go, the officer in charge of the mooring party should be carefully watching the procedure to make sure that no load comes on the line before it is secured or while it is in the process of being let go. The bridge should notify the tug that is fast only when the officer in charge of the mooring party has indicated that all men are well clear of the towline. When letting go the line, it should not be thrown off the bitts and run out. Instead, always take care to slack the line back to the fairlead in an orderly manner. 43

SAFE MOORING PROCEDURES

If the towline has an eye then heave it past the bitts to allow enough slack to be able to handle the line, then stopper off the line and put the eye on the bitts. Never try to secure the line on the bitts if you do not have enough slack line to be able to handle it easily. If the towline does not have an eye and is to be turned up on the bitts then it must always be stoppered off before it is handled. Planning a tow The route to be followed should be planned in advance, taking into account such factors as the anticipated weather, tidal streams and currents, the size, windage and displacement of the tow, and any navigational hazards. Weather routing advice should be used where available. Careful consideration should be given to the number, size and EBP of the towing ships to be employed. There should also be a contingency plan to cover the sudden onset of bad weather, particularly regarding arrangements for heaving to or taking shelter. Where the towing operation falls under the jurisdiction of the port authority, any certificate issued should specify the intended general route, indicate any special conditions, and should also note the responsibility and authority of the Masters of both the tug and tow to be able to alter the proposed route should circumstances require this action. Precautions when being towed Tows should exhibit the navigation lights, shapes and make the sound signals required by the International Regulations for Preventing Collisions at Sea, 1972. The reliability of the lights and sound signals and their ability to function for the duration of the tow should be checked well in advance of the tow taking place. When practicable, a duplicate system of lights should be on hand and ready for use. Before being towed, the watertight and weathertight integrity of the vessel should be confirmed by an inspection of the closing arrangements for all hatches, valves, air pipes, and other openings through which water might enter the towed vessel and affect its stability. It should also be confirmed that any watertight doors or other closing arrangements within the hull are securely closed and that any portable closing plates are in place. Cargo, equipment and stores being carried on a vessel being towed should be carefully examined to ensure that they are properly stowed and secured for the tow and for the weather conditions. Some port authorities have regulations which specify that for certain types of vessel or cargoes, a tow should not proceed until an inspection of the vessel to be towed has been carried out by the Tugmaster. A vessel being towed should, of course, be equipped with an anchor suitable for holding the vessel in severe weather conditions, that is securely attached to a chain cable or wire and which is arranged for quick release in an emergency. Lifejackets and lifebuoys should be provided to all those on the deck of the tow, even if only for short periods. Boarding facilities should be rigged on each side of the tow so that crew from the tug can board the towed vessel at any time.

SAFE MOORING PROCEDURES

44

In an emergency Should the tow become a direct danger to navigation, offshore structures or the coastline through breaking adrift or for any other reason, then the Master of the towing ship is bound by SOLAS V/2 to communicate the information by all the means at his disposal to ships in the vicinity, and also to the harbour authorities. The appropriate pendants should also be hoisted. In such circumstances the arrangements for recovering the tow, should it break adrift, are to seasonal weather conditions and area of operation.

45

SAFE MOORING PROCEDURES

4. Maintenance of mooring systems Most vessels operate a planned, regular maintenance schedule of all their mooring equipment – wires, ropes, winches, stoppers, shackles, windlasses and anchor chains. These maintenance schedules should be arranged in accordance with the manufacturers’ instructions.

4.1 Wire lines Inspection Regular checking and maintenance of wire lines helps prevent any damage already on them from becoming worse and reduces the danger a damaged cable can cause to those handling it. It is usually impractical or unnecessary to give a detailed inspection to the entire length of a line every time it has been used. Nevertheless, it is recommended that each wire mooring line should have its entire length carefully inspected at least once a year. There should also be regular visual inspections of each line at least once every four months. It is also recommended that no wire line be kept in service for longer than seven years. During the regular visual inspections of wire lines they should always be carefully examined for broken strands of wire, sometimes referred to as ‘snags’. The more snags there are then the weaker the cable. If you think a line has a lot of snags, report it immediately to an officer. He can then consult the manufacturer’s specifications to see if it should be scrapped. Care of wire lines The regular wire line maintenance schedules should always include such basic tasks as: ● removing the entire wire from the winch or its compartment for careful inspection ●

removing the entire wire from the winch or compartment to grease or oil it, as rust on a wire line reduces its strength very quickly

●

regularly end-for-ending each line to ensure that each end gets the same level of wear and tear. End-for-ending of each line should be done at least every four months.

Crewmembers involved in wire line inspections should have a checklist of particular potential problem areas on a line which require special attention. A typical list can include areas such as: ●

the line’s lower length, where experience has shown that it can suffer extra wear and tear, especially where the line has had considerable use and has been end-for-ended several times

●

eyes shackled to synthetic tails where there may be exceptional wear and tear. This examination should include special check on any talurit splices shackled to the tails

●

at compensation sheaves and within one metre of either side

●

at the winch drum, checking dead laps, crossover points and at the drum flanges

●

at sheaves

●

where the line passes sheaves or onto the drum during snatch or at maximum or minimum acceleration

●

areas exposed to abnormal environmental conditions

●

any other areas likely to have suffered damage during a recent mooring operation.

SAFE MOORING PROCEDURES

46

Discarding wire lines While examination of synthetic fibre lines often give several clues and some visual evidence about the condition of a rope line and how safe it is for continued use, it is less easy and straightforward to judge the condition of a wire line. The first step in assessing the condition and safety of a wire line is to consult the manufacturer’s instructions. Along with whatever information is provided in that, there are also other criteria to indicate a wire line may be ready to be withdrawn from use. For example, the number of broken wires visible on a line – three or more breaks in one or adjacent strands is a cause for concern. Damage to the end of the line or near the end is also a danger signal – more than three broken wires within 6mm of the termination means action must be taken. A reduction in diameter of more than 10% in a six or eight strand line, or more than 3% in a multistrand line, means a closer assessment of the line must be made. Signs of internal or external corrosion, signs of heat damage, slackness in the wire, areas of deformation, all of these are indications that the condition of the wire line needs to be drawn to the attention of an officer. Some shipping lines do have their own set criteria for discarding a line. One such checklist gives this advice: Wire Rope Removal Criteria Condition

Action

Deterioration of the termination

Discard

Deterioration of the core

Discard

Wear

Consider how severe it is

External corrosion

Consider how severe it is

Internal corrosion

Consider how severe it is

Deformations

Consider how severe they are

Thermal damage

Discard

Groups or areas of broken wires

Discard

Number and nature of broken wires

See manufacturer’s recommendations

Splicing wire lines Wire mooring lines usually come from the manufacturer ready fitted with steel eyes. If an eye has to be replaced then the new eye should be spliced in using at least five full tucks and two half tucks. Some shipping companies have a standard procedure of returning lines to the manufacturer to have new eyes put in. If repairs are being done on board to wires fitted to drum winches, short splices should never be used as these can cause damage to the line as it is being reeled in. The bigger a wire cable then the more difficult it becomes to splice in a new eye. Putting a new wire line on a winch drum Right and left-handed lays have to be fitted differently to winch drums. Lines with wires which have a right-hand lay should be threaded into the drum’s eye to the left of the barrel hard against the winch wall and going in an anti-clockwise, winching-in, direction. Conversely, lines

47

SAFE MOORING PROCEDURES

with wires which have a left-hand lay should only be threaded into the drum’s eye to the left of the barrel hard against the winch wall, and should be stowed onto the barrel in a clockwise, winching-in direction.

Fitting a line with a right-hand lay

Fitting a line with a left-hand lay

Fig. 19: Mooring lines made of different lay directions have to be fitted to winch drums differently to prevent damage to the lines.

4.2 Synthetic fibre lines Although synthetic lines have many advantages over wire lines, they are subject to damage more easily and so have to be more regularly and carefully inspected than wire lines. Inspection An inspection of all the ropes for abrasion damage, signs of heat damage or any other faults should take place every time a vessel de-moors. Particular attention should be given to splices and areas where the line has been in contact with the vessel’s structure. A more systematic inspection of the entire length of each line should take place at least once a year. During its inspection, a rope line should be laid out straight on the deck. A crewmember given the task of examining it should run the rope through his hands and closely examine it a half metre at a time, while always rotating it to be able to see each side of it. Strands should be lightly prised apart to examine the interior of parts of the line and check for powdering or crumbling fibres. Powdering between the strands of a rope or flakiness and crumbling in the fibres are signs of excess wear or damage to a synthetic fibre line, and signal the danger of it being reduced in strength. You must then consider whether to cut out the damaged section and splice in a new section, or whether to discard the entire line and replace it with a completely new one. Ideally, the checking process should be done using a checklist, which should include items such as: ●

deterioration of fibres

●

chafing and wear

●

strands fused by friction or other heat

●

cuts or abrasions

●

chemical damage or discoloration by an unknown agent

SAFE MOORING PROCEDURES

48

The frequent close visual inspections of rope lines must also include making sure that any splices are still in good order and, where possible, examining the inner core of the line. Like wire lines, synthetic mooring lines should also be end-for-ended regularly, at least every four months, to ensure that each end gets the same level of wear and tear. Replacing lines When replacing a worn line on a winch, the line must be wound onto the drum in the correct direction. The pay out direction should be marked on the winch’s drum. A turntable should be used to unwind a new coil of line to avoid kinking, or else it can be uncoiled from the outer end and the coil rolled out on deck. If an 8-strand rope line is to be used on winches and with more than one layer then the rope should be wound onto the winch under a load of about 10% of its Minimum Breaking Load. Splicing synthetic lines It is preferable to use mooring lines which are completely sound and undamaged. Ideally, a mooring line should not have any splices at all. However, keeping all your mooring lines entirely free of splices is not always a practicable precaution to implement. So all splices in synthetic fibre lines should have at least five tucks and use all the rope strands. It is also important to whip all the strands before splicing. One manufacturer of synthetic mooring lines recommends that a splice on a 64mm stern rope should be 1300 – 1400mm long. After being spliced, a line’s breaking load is reduced by 10%, which stays the same even if several splices are put in. Plaited lines normally have special instructions from the manufacturer as to how to put in a splice and these instructions should be followed, as should the instructions from the manufacturers of all the ropes being used. Chafing Synthetic lines are liable to chafing. To protect them, all contact surfaces such as fairleads and rollers should be clean and smooth. Any rough surfaces or jagged edges must be welded up and faired. Where steel wire ropes are also in use these can cause damage to the vessel’s decks and so there should be regular inspections to spot any damage and grind the damaged area smooth. Tube chafe guards, as recommended by the ropes’ manufacturers, can also be used. Storage Synthetic fibre lines not in use should not be left exposed in the sunshine for too long. If they have to be kept on deck they should be covered with tarpaulins. Fibre lines should be stored away in a clean, dry location out of direct sunlight. They should not be placed on concrete or rough floors or dirty decks as dirt and grit can be picked up which could damage the fibres. Instead, ropes should be stored off the floor, on something like palettes, which can allow air to circulate around them. Ropes should not be stored near chemicals or paint, or where fumes from chemicals or paint can reach them. They should always be kept away from any heat. Fibre lines should never be dried by putting them near heaters or warm spots. Care should be exercised when storing 3-strand ropes to ensure that no kinks or hockles occur. A kink can reduce the strength of a rope by 30%, and although the kink can be removed it will 49

SAFE MOORING PROCEDURES

still leave a weak point in the rope. So the rope should be coiled with the lay of the rope and uncoiled in the opposite direction. Although braided and plaited ropes cannot be hockled, poor handling can lead to excessive twisting, and so these ropes should be coiled in a figure of 8. When to scrap a rope line There are no hard clear rules as to when a synthetic fibre line needs to be scrapped and replaced, except that it must be done well before the line becomes so reduced in strength or so damaged that it becomes dangerous. Awareness of a line’s load history along with continuous examination of it before, during and after each use will help in spotting the danger signs. There are several important factors that must always be kept in mind when considering a line’s condition.

Condition or use

Effect

Line strength

Using the strongest grade of material reduces the stress on it while in use and gives it a longer lifespan

Extension

A line with low extension under a working a load can give better control, but a shock load on such a line can cause it to part unexpectedly. Lines with a very high extension under load can experience a greater amount of abrasion as they run over guides or sheaves because of the extra movement and rubbing of the line

Working load

A working load is any weight or stress under normal use, and is referred to as a percentage (%) of the line’s indicated break strength when new. A general rule is that a line’s working load should not be more than 20% of its break strength. Lines which take a load greater than this, or which experience a sudden hock load, can build up unseen damage from fatigue and cause it to part unexpectedly

Shock load

A shock load is when any sudden, unexpected heavy weight or load or stress is put on a line. Anything over 10% of a line’s normal working load is a shock load. Too many shock loads or incidences of overloading cause unseen damage to build up in a line, making it liable to part unexpectedly

Bending

Bending a line round a sharp bend causes it stress and a substantial loss of strength. Different sheaves should be used for wire and synthetic lines. The diameter of a sheave used for a synthetic line should always be at least 5 x the diameter of the line (while for some synthetic lines it should be as much as 20 x the line’s diameter)

Terminations

Although a line is most easily terminated with a knot, this is not the best practice as a knot can reduce a line’s strength by as much as 50%. Instead, lines should always be spliced according to the manufacturer’s instructions

Storage

Lines should be stored in a clean, dry, well-ventilated area (preferably on gratings) which is out of the sunlight and away from any chemicals, fumes or direct heat

SAFE MOORING PROCEDURES

50

Coiling

Badly stowed lines can cause kinks and hockles (gouges or cuts) to occur, which can reduce the strength of a line by up to 30%. Even when they are removed or repaired they still leave a weak point in the line. Lines should be coiled with the lay of the line and uncoiled in the reverse direction. Although braided and plaited lines cannot be hockled they can suffer from excessive twist from incorrect handling, and so should be coiled in a figure of 8 to ensure they run free when in use.

Table 6: Conditions or use which can affect the safety and lifespan of a line

Factor

Effect

Abrasion

The surface of a line needs regular examination. A new line coming into service quickly takes on a slightly rough, furry appearance, which is normal. However, the furriness can hide more serious abrasion damage. There should be close inspection of between a line’s strands and yarns for signs of wear. Also, look for powdering of the fibres, which signals excessive wear and a loss of strength

Stiffness

Areas or lengths of stiffness in a line indicate it has suffered shock loads, and it should be considered with caution and suspicion

Glazing

Glazed areas indicate where a line has been subject to excess heat which made its fibres melt and merge together, causing a serious loss of load strength in the line. The heat may have been experienced when the line surged on capstans or ran over non-moving sheaves or rollers, or when lines rubbed against each other. Different synthetic fibre materials have very different temperature melting points, and this needs to be taken into account, but glazed areas in a line invite closer examination and consideration of a line’s strength and safety

Diameter

With any line which has a different weave and construction in its inner core from its outer core, if it should have an area or length of varying diameter then this can indicate internal damage from overloading or shock loads, inviting closer examination and consideration of its strength and safety

Colour

All lines soon get dirty and discoloured, but patches of prominent or unusual discoloration should be closely examined as they could indicate chemical contamination

Loose strands

A few pulled or cut strands here and there in a line will have little effect on its load strength. However, these need to be considered as whether they were caused by abrasion or through internal stress. If it looks like they were caused by stress then this can soon cause more strands to part, and so the line must be closely monitored in the future

Table 7: Factors which can signal a rope is nearing retirement 51

SAFE MOORING PROCEDURES

Some shipping lines use a set inspection checklist which dictates when a line being examined must be discarded or the damaged section or sections removed and the rope spliced. One such typical checklist, suggested by a rope manufacturer, looks like this: Rope Inspection Record Rope number: Material & construction: Date first used: Dates & ports used:

Inspection Checklist Condition Rope diameter reduced by abrasion: 3 strand by 10% 8 strand by 25% 12 strand by 25% Braidline (double braid) sheath by 50% Superline sheath by 100%

Discard? ✔ ✔ ✔ ✔ ✔ ✔

Cut strands 3 strand: one or more adjacent strands cut 8 strand: one or more adjacent strands cut 12 strand: two or more adjacent strands cut Braidline (double braid) three or more adjacent strands cut Superline: any damage visible to core

✔ ✔ ✔ ✔ ✔

Irregular or uneven diameter Areas of reduced diameter Areas of enlarged diameter

✔ ✔

Inconsistent flexibility Areas of stiffness

✔ Heat fusion

Lengthy areas of fused strands

✔

Discoloration Areas of unnatural chemical discoloration

SAFE MOORING PROCEDURES

✔

52

Disposal When it is decided to scrap a line, it must be disposed of in accordance with MARPOL Annex V requirements; namely, that all redundant mooring lines must be landed ashore and disposed of in accordance with the shipping company’s own Garbage and Waste Management Plan, which should be set out in its standard procedures manual.

4.3 Winches Each winch should be checked to ensure that the ‘heave-in’ and ‘slack-out’ markings are clearly visible on the control system. If they have faded then they should be re-marked. Each winch’s clutch should be checked to ensure it is engaging smoothly and the controls are well lubricated, and that the connecting surfaces of the drive mechanism are free of wear. The condition of the drums and Gypsey head need to be examined for any pitting or abrasions which could damage the lines. Hydraulic lines and pumps must be checked regularly, including the switchgear and other electrical components. On electric winches, the switch contacts and brushes need to be inspected according to the manufacturer’s instructions. The motor bearings should be replaced at the intervals specified by the manufacturer. The motor casing should be regularly inspected for any accumulation of water. The winding’s insulation resistance must be regularly checked to ensure it is at the required level. A dropped level might indicate moisture in the insulation layers. Checking a winch brake’s condition A winch’s brake linings will be gradually reduced through normal wear and tear and, when that occurs, its brake power will also be reduced. Each winch’s brake holding power should therefore be tested, measured and recorded at least once a year, and if possible this should also be done after any long period of heavy loading (see OCIMF publication Mooring Equipment Guidelines, section 7.5.5). Each winch’s brake should also be regularly examined for excessive rust or signs of it wearing out. As the end of a passage approaches, it is important to check each winch’s brake condition and make sure that all controls and operating handles are oiled and greased and ready for use, and that the brake drums and linings are clean and reasonably dry. Even brakes that are covered will have been contaminated by salty air and seawater. Seawater, ice, oil or rust on a winch’s drum or brake lining can seriously reduce a winch’s brake holding power by as much as 75%. Moisture can be removed by running the winch slowly with the brake lightly applied. It is difficult to completely remove oil from a brake’s lining and so it usually needs to be replaced. Rust can be chipped and scraped off. Always clean up any hydraulic or lubricating oil lying on the deck around a winch. It is particularly important that all linkages are well greased and run freely. If they are not running free, the winch operator may think the brake has been properly applied when has not. This will cause a resulting loss of holding power and pay out on the rope, causing further wear on the brake.

53

SAFE MOORING PROCEDURES

4.4 Tails and shackles Nylon or other synthetic tails, along with the shackles with which they are attached to the lines, should be inspected frequently for signs of wear and corrosion. Shackles should be examined for damage, and any found to be deformed should be discarded rather than repaired as a repaired shackle will have lost its strength. A nylon tail which has been elongated more than 15% of its original length should also be discarded.

4.5 Fairleads, windlasses, chains and anchors Fairleads need to be regularly checked to ensure they are running freely and that there are no abrasions or jagged edges which could damage lines running through them. They should be regularly lubricated. If a fairlead has become stuck or is difficult to turn it can be released by using a lever and rope. After any long period when the anchors have not been used it is recommended that the anchors and cables should be walked out, with the windlass in gear, to check it is in good condition. The opportunity should be taken at the same time to grease the windlass’s bearings, brake linkages and other moving parts, and to check for dirt, rust, excess moisture or any other hazards. Windlass brakes need regular and careful maintenance, particularly with greasing and adjustment. Where there are linkages in the brake’s mechanism these must be kept well greased and running free. A badly running or damaged linkage or other part of the brake’s mechanism can cause the operator to think that the brake is fully and safely on – when instead it is just stuck. If it suddenly and unexpectedly comes free this can be dangerous. It is sometimes necessary to make adjustments to the brake to compensate for worn brake linings. The manufacturer’s instructions will tell you if this is necessary and how to do it. It is also important to regularly examine a brake’s bearing keep and ensure its nuts and cotter pins are still tightly in place. This should be done especially after the brake has had a refit or any other work has been done on it. If there is any doubt whatsoever about the efficiency of a windlass’s brake at any time then it should be fully examined and tested before being used.

SAFE MOORING PROCEDURES

54

5. Further information and reading Code of Safe Working Practice for Merchant Seamen, Maritime and Coastguard Agency United Kingdom Effective Mooring, Oil Companies International Marine Forum (OCIMF), UK Guidelines and Recommendations for the Safe Mooring of Large Ships at Piers and Sea Islands, OCIMF, Witherby & Co., London, UK, 1978. International Safety Guide for Oil Tankers and Terminals, Oil Companies International Marine Forum Hawser Guidelines and Procedures, Oil Companies International Marine Forum, 1988 Harbour Masters Report Mooring Equipment Guidelines, Oil Companies International Marine Forum Mooring Guidebook Tug Guide The Cold and Heavy Weather File, Videotel Marine International Coping with Stowaways, Videotel Marine International

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SAFE MOORING PROCEDURES

Appendix 1. Assessment quizzes (more than one answer may be correct)

Theory of Mooring 1. Which of these factors can affect a vessel’s moorings? (a) wind (b) currents (c) the way the cargo is loaded

(d) all of these

2. What will the force of a wind blowing at 30 knots at deck level be on a cargo of containers stacked 21 metres above deck level? Will it be: (a) much the same (b) less (c) greater (d) depends on the wind direction 3. How many times greater is the force of a three-knot current on a vessel’s hull compared to that of a one knot current? (a) much the same (b) double (c) three times greater (d) nine times greater 4. In ports with a large tidal range, what is the best precaution to take to maintain the vessel’s safe station? (a) use self-tensioning winches and post a regular deck watch (b) use extra-long mooring lines all round the vessel (c) use the largest steel wire lines the vessel has available (d) check the tide tables and inspect the moorings each high and low tide 5. Which of these materials is least used today for mooring lines by large commercial vessels? (a) natural fibre (b) synthetic fibre (c) high modulus synthetic fibre (d) steel wire 6. What is a 6 x 36 mooring line? (a) a line constructed from six strands of an inner core made of one type of synthetic fibre material surrounded by 36 strands of a second layer of a different type of synthetic fibre material (b) a line constructed from 36 strands of an inner core made of steel wire surrounded by six strands of a second layer of synthetic fibre material (c) a line constructed from six strands of an inner core made of steel wire surrounded by 36 strands of a second layer of steel wire (d) a line constructed from 36 strands of an inner core made of one type of synthetic fibre material surrounded by six strands of a second layer made from a different type of synthetic fibre material 7. What does MBL stand for? (a) Maximum Bollard Layers (c) Maximum Ballast Level

(b) Maximum Breaking Load (d) Maximum Berth Length

8. What does ABL stand for? (a) Average Breaking Load (c) Auxiliary Buoy Lead

(b) Admiralty Ballast Limitations (d) Afterdeck Buoyancy Line

SAFE MOORING PROCEDURES

56

9. What is the least MBL a carpenter stopper should have when used on a wire mooring line? (a) at least half that of the line (b) the same as the line (c) twice that of the line (d) three times that of the line 10. Which of these is the strongest type of synthetic fibre rope in common use today? (a) nylon (b) aramid (c) polypropylene (d) HMPE 11. Which is the only one of these lines that floats? (a) polyester (b) polyester/polypropylene (c) polypropylene (d) aramid 12. How much elasticity does a high modulus synthetic fibre rope typically have? (a) None (b) 1 – 2% (c) 4 – 5% (d) about 10% 13. How much elasticity can a conventional synthetic fibre rope typically have in some circumstances? (a) about 4 – 5% (b) about 10% (c) about 30% (d) about 60% 14. If your vessel is using a mix of wire and synthetic fibre lines in its mooring system, which lines should the synthetic lines preferably be used for rather than wire? (a) head and stern lines (b) spring and breast lines (c) spring and head lines (d) breast and stern lines 15. The speeds of the currents in a coastal harbour are: (a) unpredictable (b) predicted in tide current tables (c) generally constant (d) usually too weak to have any effect on a well-moored vessel

Answers 1. (d); 2. (c); 3. (d); 4. (a); 5. (a); 6. (c); 7. (b); 8. (a); 9. (b); 10. (b); 11. (c); 12. (b); 13. (c); 14. (a); 15. (a); 57

SAFE MOORING PROCEDURES

Safe Mooring Practice 1. What is the correct way to thread a steel wire mooring with a right-handed lay onto a winch’s drum barrel? (a) start in the centre of the drum and run the line from right to left and always in a clockwise direction (b) start hard against the barrel’s right wall and going in clockwise, winching-in direction (c) start hard against the barrel’s left wall and going in an clockwise, winching-out direction (d) start hard against the barrel’s left wall and going in an anti-clockwise, winching-in direction 2. (a) (b) (c) (d)

What is the difference between the render power of a winch and its heave power? The heave power is always greater than the render power The heave power is always less than the render power They are equal It depends on the type of winch

3. What is the revolving drum of a winch used to haul lines known as? (a) bull gear (b) gypsy (c) spinnaker (d) wildcat 4. What is known as a wildcat during mooring operations? (a) a deeply grooved drum on the windlass with sprockets which slot into the links of the anchor chain (b) a winch which is running out of control (c) a mooring line which has jumped off the gypsy (d) a mooring line which has parted and has whiplashed back across the deck 5. How are winch pipelines best protected from damage by ice? (a) applying grease to them (b) draining all fluid out of them when not in use (c) keeping them covered up (d) running a blowtorch along them every 6 hours 6. (a) (b) (c) (d)

What is the best way to prevent machinery like winches and windlasses from icing up? run the machinery for ten minutes during every watch keep them well greased with a mix of grease and anti-freeze keep them covered up all of these

7. (a) (b) (c) (d)

What is the best way to prevent mooring lines from freezing solid in bad weather? keep them under cover until they are needed keep them well greased up clear the ice of them daily using blowtorches and wire brushes coat them with anti-freeze solution six hours before mooring operations begin

8. What should be the minimum holding power of a winch’s brake in relation to the mooring line on it? (a) 25% (b) 40% (c) 60% (d) 100% 9. What does CBM stand for? (a) Centre of Buoyancy Mark (c) Capstan Barrel Meridian SAFE MOORING PROCEDURES

(b) Conventional Buoy Mooring (d) Channel Buoy Map 58

10. What does MBM stand for? (a) Main Breakwater Mark (c) Mooring Berth Measurements

(b) Middle Berth Mooring (d) Multi-Buoy Mooring

11. As your vessel is being towed by a tug you notice another ship coming from starboard is about to pass between you and the tug. What would you expect the tug to do? (a) turn hard to port (b) turn hard to starboard (c) sever the towline (d) slow down and pay out the towline 12. What does girting mean? (a) a vessel being damaged or capsized by its towline (b) making a formal complaint of bad seamanship (c) a tug being forced backwards by its tow (d) a towline parting 13. Who has the ultimate and final responsibility for giving orders regarding what to do with a towline attached to your vessel? (a) the Tugmaster (b) your vessel’s Master (c) the Pilot (d) your vessel’s deck officer 14. What is the usual order of engaging mooring lines? (a) spring lines first, then breast lines, then head lines and stern lines (b) head and stern lines first, then spring lines, then breast lines (c) spring lines first, then head and stern lines, then breast lines (d) head line first, then breast lines and spring lines together, then the stern line 15. When unmooring the vessel, who decides in which order the lines are to be let go? (a) the officer in charge of the mooring party (b) the Harbourmaster (c) the person in charge of the linesmen ashore (d) the Master (in consultation with the Pilot)

Answers 1. (d); 2. (b); 3. (b); 4. (a); 5. (c); 6. (d); 7. (a); 8. (c); 9. (b); 10. (d); 11. (c); 12. (a) 13. (b) 14. (a); 15. (d)

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Maintenance of Mooring Systems 1. How are steel wire mooring lines usually treated to prevent corrosion? (a) galvanised (b) greased (c) copper plated (d) manganese-coated 2. What is the first and most obvious signs on a wire mooring line indicating it is becoming worn? (a) heavy rust on several sections (b) a singing noise when it is under strain (c) snags appearing along its length (d) it becomes more pliant and easier to handle each time it is used 3. (a) (b) (c) (d)

What does a glazed surface on a synthetic rope indicate? it has been treated with an anti-corrosion solution it is a high-modulus rope it has lost a large part of its strength it has been contaminated with oil and needs to be cleaned

4. How many broken strands in a wire line mean it must be removed from service? (a) 5% (b) 10% (c) 20% (d) 25% 5. What percentage of broken strands in an eye of a wire line mean it must be re-made? (a) 10% (b) 15% (c) 20% (d) 25% 6. (a) (b) (c) (d)

What do polyethylene ropes have to be checked for in particular? extra stretching discolouring due to chemical sensitivity unpleasant smell indicating chemical attack burn damage because of their low melting temperature

7. What elongation on a nylon tail would mean it has to be discarded? (a) 10% (b) 15% (c) 25% (d) 30% 8. How much abrasion damage to a synthetic fibre rope mean it must be discarded? (a) Any sign of abrasion damage means it must be discarded (b) 5% (c) 10% (d) 15% 9. (a) (b) (c) (d)

How much rust can be allowed to build up on a wire line before it must be removed? none should be allowed small surface patches here and there are alright when any rust patch becomes so hard it cannot be scraped off with a pocket knife when there is continuous rust longer than an arm’s length

10. What is the minimum frequency in which synthetic lines should be end-for-ended? (a) after every third mooring in which it has been used (b) monthly (c) quarterly (d) annually Answers 1. (a); 2. (c); 3. (c); 4. (b); 5. (a); 6. (d); 7. (b); 8. (c); 9. (a); 10. (c)

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Appendix 2. Properties of wire and synthetic mooring lines Steel wire lines, or ‘cables’ The standard steel wire line Most standard marine wire mooring lines consist of a central solid core of flexible steel or synthetic fibre, surrounded by an outer layer of six thinner wire lines. These six outer lines are themselves each made up of either 36 or 41 thinner, individual lengths of solid wire line. Fibre core

6 x 36

Wire core

6 x 41

6 x 36

6 x 41

Fig. 20: Cross-sections of typical wire mooring cables The different constructions and sizes of wire cables are described by the number of strands and the number of wires in each strand. For example, a smaller 6 x 7 wire cable will consist of six strands over a steel wire core, with each strand made up of seven wires (six wires twisted around a central one). Steel wire lines are usually galvanised to help prevent corrosion from seawater. Wire cables with synthetic fibre cores are best suited to when the vessel being moored needs smaller mooring lines which are easier to handle manually, such as if they need to be ‘turned up’ on bitts or bollards.

95 D

90

O

LC

E RD

RO

5

S PE

P

D DE

RO

ES

10

R

RE FIB

E TE

S

CO

85

15

80

20

75 8

10

12

14

16

18

20

22

25 24

Percentage of original breaking strength

Percentage of original breaking strength

Wire cables with steel cores are best suited to larger vessels where the mooring cables will be not be manhandled so much by crewmembers, but instead will be played out and taken in on a storage drum winch. A steel core in a wire line provides it with greater strength and helps reduce the effect of the crushing it receives as it is wound onto the drum and a possible gradual reduction in its minimum breaking load (or MBL, explained below) which it can suffer as a result of being bent around the drum (Fig. 21 shows the effect of a wire line being bent in a winch’s drum).

Fig. 21: The loss of breaking load when wire lines are bent around winch drums or pulleys which have small diameters.

Bending ratio-drum or pulley/rope dia. ratio 61

SAFE MOORING PROCEDURES

Many new ships today are built with mooring lines, both wire and synthetic, stored and terminated on self-tensioning winches, so making the use of mooring bitts unnecessary. This arrangement has the added advantage of allowing just two crewmembers to form a mooring party if necessary in some circumstances. The language of steel wires The manufacturers of wire mooring lines use their own terms and words, and knowing some of these can help you understand how different types of wire line are made and what their advantages are. Size The size of wire mooring line being used is usually referred to by the number of the smallest individual wire lines which go into making up each of its six outer strands, for example, a ‘6 by 36’, or a ‘6 by 41’. These wire lines are made of different grades of steel, but are mainly either 145 kg/mm2 or, more often, the 180 kg/mm2 grade which combines better overall performance with a high load tolerance. Wire cables such as these used for mooring are made in diameters, or thickness, ranging from 22mm to 40mm. Lay: the twisting of individual strands of wire, or of lines made up of many of them twisted together to form an even thicker line.

Fig. 22: Three strands being intertwined in a right-hand lay to form a bigger strand which, in turn, will then be used with other identical strands to make up a full-size mooring line.

Ordinary lay: when the lay (or direction of twist) of the individual wires making up an outer, bigger cable are twisted in the direction opposite to that in which the outer, bigger cable itself is twisted. Right or left hand lay: the direction the strands are twisted in around the central core. Mooring lines supplied to vessels are usually right hand lay, unless the vessel’s owners or Master specifies otherwise. SAFE MOORING PROCEDURES

62

Fig. 23: A left-hand ordinary lay mooring line (left) and a right-hand ordinary lay mooring line (right).

Equal lay: when successive layers of wires are twisted over the preceding inner layers at the same angle. Fig. 24: Equal lay construction of a mooring line. Size for size, mooring lines made of equal lay are stronger than those made of cross lay (see below), having up to 14% greater MBL (see below) due to less spinning loss (see below), while equal lay mooring lines also suffer less internal wear than those made of cross lay. Cross lay: when successive layers of wires are twisted over the preceding inner layers at increasingly greater angles.

Fig. 25: Mooring lines made of cross lay construction are more flexible than those made of equal lay, but they are not as strong and are more liable to internal wear and tear because of the greater area of contact between the different layers of coiling wires.

Lang’s lay: when the lay (or direction of twist) of the individual wires making up an outer, bigger cable are twisted in the same direction in which the outer, bigger cable is twisted. Lang’s lay is not suitable for making mooring lines.

Fig. 26: Although a line made up using Lang’s lay is a stronger construction than ordinary lay it has a tendency to untwist and come apart more quickly, and so is unsuitable to be used as a mooring line.

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Minimum Breaking Load (MBL): The least load or weight at which the manufacturer guarantees a wire mooring line will definitely part, having been established during tests at the factory. However, a mooring line subjected to sudden or extreme additional marine and other natural forces, such as wind and currents, can still snap apart when the vessel moored is less than the line’s MBL. New lines should always come with a certificate of MBL, which should be consulted to understand its specification. Aggregate Breaking Load (ABL): The sum total taken together of all the breaking loads of each of the individual wires used to make one mooring line Spinning loss: During the manufacture of wire mooring cables some of its strands suffer damage and lose strength, so the real breaking point of a mooring cable is always less than its stated ABL. The loss of strength is known as its spinning loss (as when all the individual strands are being woven together, or ‘spun’) Strand: The largest single element used in the final stage of the rope-making process, done by the joining and twisting or braiding together several yarns or groups of yarns Yield point: The point at which a mooring line experiences a very sharp increase in the stress upon it as the load it is holding increases. It is at this point that a mooring line can suffer distortion and damage. Synthetic fibre lines, or ‘ropes’ In most vessels around the world, the use of synthetic fibre lines has now almost entirely replaced that of natural fibre lines, both of which are still often referred to as ‘ropes’. There is a wide range of synthetic fibre lines available, made of materials such as nylon, polypropylene and polyester, and very often lines made of combinations of several different synthetic materials. With the use of synthetic lines so widespread it is important that mariners thoroughly understand their different properties - the different advantages and disadvantages each may have - as these can be very substantial. Understanding these differences could one day help to prevent an accident. Construction of synthetic lines Synthetic lines generally are made up in one of two different forms of construction, or ‘lays’. Synthetic lines are made in either a hawser lay or in plaited lay (sometimes also referred to as ‘braided’). Synthetic lines made of hawser lay are not in much use today because they can be prone to kinking and are also stiff to handle. Instead, the most common constructions of synthetic fibre lines are ‘8-strand plaited’ (sometimes called ‘square braid’), and ‘double braid’ (sometimes called ‘braid on braid’).

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64

Fig. 27: Hawser-laid rope mooring lines are seldom used now.

Fig. 28: 8-strand, or square braid, uses a mix of right and left-hand lays is almost unkinkable and is very flexible.

Fig. 29: This plaited inner line with a tight woven outer sheath made of a different material is used for first line ashore, or as spring, head or breast lines.

Synthetic fibre lines are also available in a construction similar to wire lines, using six strands of nylon wound around a solid nylon core. This construction, given nylon’s already high strength, provides even an even greater MBL and lower elasticity than most other synthetic lines of a comparable size. Recently available are other new forms of constructions of synthetic lines, designed to provide even greater strength and reduced elasticity and for use in very specific situations. The manufacturers’ specifications for these specialised lines should always be checked to make sure their properties and MBL are appropriate for the task you are planning. Rope type Nylon Polyester Polypropylene Polyester/polypropylene HMPE Aramid 6-strand nylon

Weight (kg/100m)

Typical breaking load (tonnes)

Typical extension (at 50% breaking load)

265 328 185 242 184 293 245

72 67 47 58 240 160 81

12% 10% 9% 14% 1% 2.5% 16%

Table 9: Typical weight, breaking load and elasticity of an 8-strand plaited line of 64mm diameter made out of different synthetic fibres, along with the results for a special 6-strand nylon line (note: these figures are for a used line, as the extension for new lines would be much greater). 65

SAFE MOORING PROCEDURES

Diameter (mm)

Nylon

Polyester

Polypropylene

Polyester /Polypropylene

Aramid

6-strand Nylon

40 44 48 52 56 60 64 72 80

30 36 42 49 56 64 72 90 110

27 33 38 45 51 57 67 83 103

19 23 27 31 36 41 47 58 72

24 28 33 39 45 50 58 72 88

73 88 105 123 145 163 185 232 290

31 42 50 54 66 74 81 114 135

Table 10: Typical MBL in tonnes of 8-strand plaited lines and of a special 6-strand nylon line Differences in synthetic fibre materials: learning your lines The four most common materials from which synthetic mooring lines are made are nylon, polyester, polypropylene, and a mixture of polyester and polypropylene. All have different properties and handling characteristics and these are listed on the next few pages. Nylon This is the strongest of the conventional synthetic fibre rope materials. Nylon, also known by its chemical name polyamide, has been widely used in marine mooring and towing lines since the 1950s. It has the lowest stiffness modulus, and thus it is favoured where high extension is very important. It is the strongest of the conventional synthetic fibres when dry. However, when nylon ropes become wet they can lose up to 20% of their strength. Wet nylon can also suffer loss of strength from creep and internal abrasion from repeated heavy loading, generally resulting in shorter service life. Good points:

* very high strength even with sustained loading * strong resistance to chemical attack from alkalis, oils and organic solvents

Bad points:

* can be damaged by acids * its high extension makes it no use for mooring vessels which need to be kept very steady

Floats?

No

Melts at:

250ºC

Polyester This is the heaviest of the synthetic fibre rope materials. Polyester mooring lines are longer lasting than nylon, and very strong polyester ropes are now being used which are made from newer types of high-quality polyester fibres. Polyester ropes can be as strong as nylon when dry and do not lose strength when wet. Polyester ropes are therefore becoming more favoured in many conventional marine applications, and are good candidates for deep water mooring systems. Good points:

* lowest extension under load of all synthetic fibres (except for Aramid)

Bad points:

* not as strong as nylon * heavy * can be attacked by alkalis

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66

Floats?

No

Melts at:

230º – 260º C

Polypropylene Polypropylene ropes are no longer allowed to be used as mooring lines. This material is the lightest of the synthetic fibre ropes and comes in different grades. Because it is lighter than water, ropes made of polypropylene were often favoured for this reason, and also for their lower cost. However, polypropylene is weaker than either nylon or polyester. Polypropylene rope can heat up and lose strength during high-speed cyclic loading and may creep under high loads. Due their ability to float, polypropylene ropes are considered ideal for use as messenger lines, but they are not allowed by the International Safety Guide for Oil Tankers and Terminals for any other mooring purposes. Polypropylene and polyester yarns are sometimes combined in ropes. These hybrid ropes can have strength and stiffness properties similar to those of all-polyester ropes but with lower weight and cost, and they can have greater resistance to surface abrasion and heat build-up than all-polypropylene ropes. Good points:

* resists chemical attack by acids, alkalis and oils * Does not lose strength when wet

Bad points:

* can be attacked by bleaching agents and some industrial solvents

Floats?

Yes

Melts at:

170º C

Polyester/Polypropylene This is the much lighter than polyester, but heavier than polypropylene and makes for a useful general purpose line Good points:

* * * * *

Bad points:

* not as light as polypropylene and not as strong as polyester or nylon

Floats?

No

Melts at:

170º C

resists chemical attack by acids, alkalis and oils moderately light and moderately strong highest UV resistance of any synthetic fibre material good abrasion resistance good strength-to-weight ratio

Aramid This is the strongest of all the synthetic fibre materials, an extra-high modulus synthetic fibre, and with the lowest extension. Aramid was the first high-performance fibre to be developed and was introduced about 40 years ago. It was first used for mooring buoys, then later for deep water platforms. Today it is used extensively for ships’ mooring systems particularly for sprint and breast lines. Aramid fibres are made up of tiny crystal particles woven into individual strands which are then woven into mooring lines. To illustrate its strength, the body armour worn by policemen and soldiers is made of Aramid.

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SAFE MOORING PROCEDURES

Good points:

* * * * * * * * *

exceptional strength, equal to steel good resistance to cuts resists chemical attack excellent strength-to-weight ratio highest resistance to heat of any synthetic fibre material hardly any creep does not rust does not need lubrication lighter and easier to handle by mooring gangs than wire lines

Bad points:

* * * * * * *

heavy not suitable for use in large braided or plaited lines expensive moderate-to-poor resistance to abrasion difficult to splice can suffer from fatigue leading to failure lighter and easier to handle by mooring gangs than wire lines

Floats?

No

Melts at:

260º C

HMPE High Modulus Polyethylene (HMPE) is almost as strong as Aramid. High modulus polyethylene (HMPE) lines are made from a crystalline type of material similar to Aramid, although chemically different. HMPE is nearly as strong as strong as Aramid, and it floats in water. However, it has a relatively low melting point, and also has a tendency to creep and so can break at sustained high loads. Nevertheless, HMPE does not suffer from axial compression fatigue problems, has a low coefficient of friction, and has very good abrasion resistance. HMPE is particularly highly resistant to acids, caustic soda, benzene and other aggressive materials and contaminants.

Good points:

* * * * * * *

exceptional strength, equal to steel highest strength-to-weight ratio of any synthetic fibre highest abrasion resistance ratio of any synthetic fibre low stretch good fatigue resistance to tension, bending, abrasion and cuts resists chemical attack good flex fatigue resistance

Bad points:

* * * *

low melt point more prone to damage than steel wires expensive susceptible to creep

Floats?

Yes

Melts at:

150º C

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68

‘Pros’ and ‘cons’ between wire , HMPE and Aramid lines Characteristics wire HMPE Aramid Resists abrasion

✔

X

X

Floats

X

X

X

Cost

✔

X

X

Easy to handle

X

✔

✔

Life span

X

✔

✔

Easy to maintain

X

✔

✔

Manpower needed

X

✔

✔

Mooring time

X

✔

✔

Pollution risk

X

✔

✔

Safety

X

✔

✔

Easy to splice

X

✔

✔

Stretch or elasticity

X

✔

✔

Weight

X

✔

✔

UV resistance

✔

✔

✔

Table 11: Medium and large vessels can use a combination of both types of synthetic lines and also wire lines for mooring, although such a mixture can make sometimes it much more difficult to work out how best to set up and monitor the ship’s mooring system so as to effectively counteract the forces working against it. The main problem with mixing the three different types of lines is their very different levels of elasticity. Newer high performance lines Vectran, a liquid crystal aromatic polyester (LCAP), is a more recent type of high modulus line, mostly being used at present by shore-based industries. It has better resistance to axial compression fatigue and creep than Aramid, although it is also much more expensive than either Aramid or HMPE. However, rope manufacturers are currently looking at ways of producing less expensive LCAP lines for use in mooring. Another new high-performance synthetic fibre which may soon come into service as mooring lines is polybenzoxazole (PBO), which has recently been developed by the United States Air Force. PBO is very, very expensive, although it has even higher strength and higher modulus than any other high performance synthetic fibre, except for some very special, extremely high modulus types of Aramid such as Kevlar 49.

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Appendix 3. Case studies of mooring accidents Case study 1: A damaged line costs a man his leg The morning after Christmas Day the young port services officer at Freemantle Port in Australia returned to duty after two days leave. While helping to supervise the mooring of a liner trade vessel which plied between Asia and Australia, the eye of a mooring line gave way while the vessel’s crew was applying tension to one of its stern lines. In less than a fraction of a second, the remnant of the line attached to the bollard on the quay whipped across to where the officer was standing and sliced almost right through his right leg just below the knee, leaving it hanging on by a few scraps of sinew and skin. Although rushed to hospital immediately, the young man’s leg had to be amputated. Later investigation revealed that the line had been previously damaged, but that no one had thought to splice out the damaged section or to replace the line.

Case study 2: The officer said: ‘Two ropes will be enough’, but one parted and sliced off his head While mooring at a temporary berth before moving next day into its designated berth for taking on cargo, the officer in charge of the ore carrier’s deck party gave the order to use just two mooring lines to secure the vessel to its position, believing that as it was light in the water without its cargo of aggregates, and with good weather and sea conditions, then just the two lines would be sufficient. However, he had failed to take into account two factors: firstly, that the tide was on the turn, and quickly brought about a fast current; secondly, and more dangerously, nobody had noticed that one of 8-strand conventional synthetic fibre mooring lines being used had been reduced through abrasion by nearly one third of its diameter along a half-metre of its length. This line should have been replaced if the damage had been spotted. The effect of the current on the damaged line was to cause it to part without any warning, giving the whiplashing length attached to the ship such speed and force that it struck the officer, who was unfortunately standing in the line’s snapback zone, and sliced off part of his head, killing him instantly.

Case study 3: Nobody noticed the lines had become too tense A container ship was unloading in an Alaskan port which is known to have a large rise and fall of tide. The ship was suddenly hit by squalls which, despite it having run out extra mooring lines, blew the vessel off the quay. The deck officer went forward with some crew to adjust the lines. While he was standing on the mooring deck one of the lines parted and whiplashed back, and before he could move out of the way it struck him in the head causing severe injuries. Nobody had previously noticed any warning signs that some of the mooring lines had been put under extreme tension when the squall shifted the vessel. If they had realised the lines were so taut as to be dangerous then they should not have gone out on to the mooring deck until the bow thruster had been started and was able to take some of the weight off the ropes.

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Case study 4: The chief put his foot in it – and almost lost it The crew of a tanker preparing to sail had been sent to stations and the vessel was singled up while awaiting customs clearance. The last two lines on the foredeck were those permanently stored on the windlass drums. Customs clearance was received and the order given to let go forward. When the foredeck crew tried to slack down the line on the starboard drum for letting go it would not do so. No one had realised that the berth had been exposed to a heavy swell which had caused the vessel to surge continually whilst alongside. The surging action had resulted in the mooring rope on the starboard windlass drum becoming buried in itself. And so when someone went to slacken down the line it jammed. The chief officer attempted to pull the line clear. To do so he put his foot on the winchbearing A-frame support located forward of the starboard drum. The A-frame support was close to the drum face, which had four flat bar stiffeners welded to it. The stiffeners passed close to the support, creating a guillotine-like effect. When the drum suddenly began to rotate the officer’s foot was caught in the machinery through the gap, and despite wearing steel-capped safety boots he suffered severe injury to his toes. Fortunately, he was immediately rushed to a hospital where extensive microsurgery managed to save his foot. The ship’s winch drums were modified soon afterwards to prevent such an accident happening again. Nevertheless, this shows the dangers of working too close to winches. The accident would have been avoided if the chief officer had used some other way of freeing the rope, which did not involve getting so close to the winch’s machinery. One possible way might have been to put a stopper on the mooring rope while continuing to veer, so using the power of the winch to free the rope, but without it being necessary for anyone to be too close to it.

Case study 5: Not securing the winch cost him his hand While doing routine servicing of a hydraulic winch, an engineer was injecting a de-greasing solution at 90 bar. Although he had switched the winch off at the controls, he had failed, however, to disconnect the power supply completely. During the work on the internal mechanics of the winch he inadvertently nudged the ‘on’ circuit, setting the gears in motion. His hand was crushed, and later had to be amputated. The instruction manual for the winch would have specified that it should have been completely disconnected from the power source before any work was undertaken on its interior mechanical assembly.

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SAFE MOORING PROCEDURES

Case study 6: A risk analysis can save a lot of later grief A tanker was approaching an oil jetty, one which had been specifically designed for small vessels, typical of many such jetties in South East Asia. The berth consisted of a central section containing the loading arms, on either side of which was a mooring dolphin connected to the berth by walkways. The tanker manoeuvred alongside the berth in a light condition and without tug assistance. Its forward draft was only 0.6 metres, and the wind was blowing onto the berth as the Master made his approach into the current. As he stopped his vessel parallel to the berth, the high windage forward caused the bows to fall off. The bow of the vessel entered the space between the dolphin and the berth, coming to rest with the bow in contact with the central section. To extricate himself the Mmaster put his engines astern and, in doing so, the focsle railing caught one of the chicksands and severely damaged it. This incident could have been avoided if a proper risk analysis of the mooring had been made in advance. Had this been done then a decision might have been taken to ballast the forward end of the tanker to reduce the windage and increase the grip of the forefoot in the water, or if operational considerations made this impracticable, then the assistance of a tug might have been considered. Repairs to the loading arm cost US$100,000. In a similar incident another vessel demolished four chicksands, causing US$2million worth of damage.

Case study 7: Never assume anything during mooring operations A 9,000 tonne vessel was manoeuvring alongside a berth under pilotage, but without tug assistance. The intended berth was between another vessel and a floating pontoon. Two head ropes were run ashore by the forward mooring boat. The Pilot then called in the stern mooring boat to run the after back spring, since the tide was from ahead. However, before this could be done, the vessel started to be set astern and the pilot instructed the stern mooring boat to keep clear because he was about to use the main engines. The vessel was manoeuvred ahead and the Pilot again called in the stern mooring boat. However, there was some difficulty in securing the two head ropes ashore, and the vessel started to drift astern again. Although the Pilot could not see the stern mooring boat he assumed it was clear of his propellers and began to use the main engines again to manoeuvre the vessel ahead. The wash from the propellers caused the stern mooring boat to capsize, throwing its two crewmen into the water. Fortunately, both men were wearing self-inflating life jackets and managed to climb uninjured onto the floating pontoon. This event demonstrates the need for good communications between all those involved in mooring operations, and for always getting confirmation that something that should have been done has indeed been done, such as that mooring boats are clear of the propellers before the main engines are used. The accident also demonstrates the need for everyone engaged in mooring operations to always wear an inflatable life-jacket. SAFE MOORING PROCEDURES

72

With hindsight, it is probable in this case that if a single head rope could have been secured quickly it would have enabled the vessel to be held against the tide without any further need of the main engines

Case study 8: Watch that line! A small harbour tug was acting as stern tug to a 920,000 tonne vessel which was berthing in good weather and tidal conditions. In repositioning herself and passing across the stern of the larger ship when the ship's engines were running ahead, the towline came under very heavy load and quickly reached an angle of 90o to the fore and aft lines, causing the tug to capsize within seconds. Both crewmembers on the tug drowned.

Case study 9: When patching up can kill A small tug was towing a barge at the approaches to a pier off the west coast of Ireland. The crew of the tug had used an old car tyre to join two lengths of rope to form a longer tow line. During the tow the tug accelerated, causing the tow line to part where it was tied to the tyre. The part of the line still attached to the tyre whiplashed back towards the barge, where it struck and killed a crewman standing at its bow.

Case study 10: Out of sight, out of mind – then dead While assisting with the berthing of a tanker, a tug’s tow rope was led from its towing hook to the centreline at the stern of the tanker. A bridle wire was led from a winch through a swivel block, located at the stern of the tug, to a saddle attachment positioned around the tow rope. The mooring manoeuvres reached a stage when the use of the bridle arrangement was no longer needed, and two of the tug’s crew left the wheelhouse to get ready to retrieve the bridle wire. One of them went to the after working deck and stood between the leads of the tow rope and the bridle wire. When the bridle wire was slackened, done from a control position in the wheelhouse, the slackening caused the saddle attachment to slide very quickly down the tow rope which, in turn, caused the bridle wire to hit the crewman, killing him instantly. This event demonstrates the importance of making sure that all those engaged in mooring operations should be clearly visible to whoever is in charge, or that they are in communication with the supervisor. In this case, the dead man had been in a position on the after working deck which was out of sight of both the Tugmaster and the bridle wire winch operator at their control positions in the wheelhouse.

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Case study 11: Only six minutes from disaster A 10,000 tonne cargo vessel was being towed upriver at 5 knots at night to its discharge berth by two tugs when they came into an unexpected fog bank. The river was narrow and the bow and stern towlines were each only 30 metres long. In the fog the vessel’s Master and the Skippers of both tugs all became disorientated by lights on the river bank on each side. During the confusion, to avoid hitting each other and with the danger of running aground or the towlines girting the tugs, all three vessels each took their own independent actions. However, within six minutes all three vessels had collided with each other. At the later inquiry the reasons for the disaster were found to be complex, but at the heart of the accident was found to be a fundamental failure of communications between all three skippers and the pilot on board the towed vessel, as well as a very praiseworthy reluctance by the two tug skippers to immediately slip their towlines at the first hint of trouble because they wanted to try to save their tow from grounding. An important lesson learned from this event was that during towing operations good communications between everyone involved is vital – especially in case weather and visibility conditions worsen.

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