Anchoring Safely

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The Steamship Mutual Underwriting Association

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VIDEOTEL PRODUCTIONS ANCHORING SAFELY

ANCHORING SAFELY

A VIDEOTEL PRODUCTION

In association with

The Steamship Mutual Underwriting Association [Bermuda] Limited

AUTHOR

Johnathan Priest

rnVIDEOTEL

p r o d u c t i o n s

84 Newman Street, London

wn

3EU Telephone : +44(0]20 7299 1800

Facsimile: +44(0]20 7299 1818

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VIDEOTEl PRODUCTIONS ANCHORING SAFELY

ANCHORING SAFE Y

A

VIDEOTEL PRODU

C

TION

In association with

The Steamship Mutual Underwriting Association [Bermudal Limited

THE PRODUCERS WO ULD LIKE TO ACKNOWLEDGE THE ASSISTANCE OF

The Master, Officers and Crew of MV Berge Nord Bergesen d.y. ASA

International Maritime Organization The Maersk Company

The Steamship Mutual Underwriting Association [Bermudal Ltd United Salvage Ltd

Warsash Maritime Centre World Wide Shipping

CONSULTANTS

Sir William Codrington Captain Allan MacDowall

PRODUCER

Peter Wilde

WRITER/DIRECTOR

Charles Leigh-Bennett

PRINT AUTHOR

Johnathan Priest WARNING

Any unauthorised copying, hiring, lending, exhibition diffusion, sale, public performance or othe'r exploitation of this video is strictly prohibited and may result in prosecution.

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

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INTRODUCTION

4

What subject does this training cover?

4

How to use this guide?

4

What does this guide provide for trainers?

4 SECTION 1 ANCHORING

-

THE HAZARDS

5 SECT

I

ON 2 ANCHORING EQUIPMENT

6

2.1

The anchor

6

2.2

The windlass

6

2.3

Preventing damage to the windlass motor and clutch

7

2.4

Preventing damage to the windlass brake

8 SECTION 3 PREPARING TO ANCHOR

·

9

3.1

Lying at single anchor

9

3.2

Basic procedure

10 SECTION

4 ANCHORING A VERY LARGE VESSEL

12

4 .

1

Is equ ipment keeping pace?

₁₂

4.2

The traditional Fore & Aft [in-line] approach

13 SECTION

5 AN ALTERNATIVE APPROACH TO

ANCHORING

16

5 .

1

The U-turn method

16

5.2

Axial verses rotational forces

16 SECTION 6 USING THE U-TURN METHOD

18

6.1

Operational briefing

18

6.2

Approach to anchorage

19 SECTION 7 ANCHOR WATCH AND SECURITY

21 SECTION 8 WEIGHING ANCHOR

22

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WHAT SUBJECT DOES THIS TRAINING GUIDE COVER?

This training guide examines the general principles of safe anchoring for medium to large vessels including VLCCs and bulk carriers. The need to review anchoring procedures is born out of an increased incidence of personal injuries, damage to anchoring equipment and even loss of ships caused by the difficulties of anchoring large vessels. An overview is provided of the proper use of anchoring equipment and its mechanical tolerances. An alternative to the traditional approach to laying anchor is also described.

HOW TO USE THIS GUIDE?

The guide is published in an association with a video of the same title 'Anchoring Safely' which provides an overview of anchoring and which demonstrates some of the techniques described herein. The guide provides the theoretical background to anchoring procedures demonstrated in the video and describes them in far greater detail. To this day, anchoring remains a hotly debated topic and companies and their masters have strongly hel.d opinions as to how it should be carried out, many of which are also a matter of company policy. The publishers wish to make it clear that the information provided in the video and guide is based on widely accepted best practice but is in no way intended to provide anything other than guidance.

WHAT DOES THIS GUIDE PROVIDE FOR TRAINERS?

This video and guide provide trainers with a concise overview of the basic principles of safe anchoring and will help them to increase awareness of this vitally important aspect of seamanship. The procedures described are based on a sound understanding of engineering tolerances of anchoring equipment and the dangers to personnel and equipment associated its misuse. The main procedures for laying and weighing anchor are described as well as the requirements for anchor watch. The trainer's experience and expertise remain essential in interpreting these

procedures in the context of the variety of physical conditions and local constraints that mariners will encounter.

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VIDEOTEL PRODUCTIONS AN CHORING SAFELY

ANCHORING - THE HAZARDS

Anchoring is a highly skilled operation that requires

leadership, teamwork and the utmost vigiLance from the

time the ship arrives at port to the moment the anchor is

weighed. Ships often have to go to anchor unexpectedly

either due to changes in berth availability or weather

conditions. Anchors and windlasses need to be well

maintained and ready for use at any time in port

approaches and harbours.

Pressure on berths around the world means that merchant ships may have to remain at anchor for long periods. This is demanding on masters, pilots and crews, especially on the largest vessels where exceptional care is required to anchor safely and without causing damage to other shipping

or port facilities.

There have been increasing reports of accidents to ships while lying at anchor including drifting, collision and stranding caused by dragging. Many accidents and equipment losses also occur when the anchor is being laid or weighed. Reported incidents tell of vessels losing the anchor due to the cable parting, of vessels whose windlass brake caught fire and more than one vessel whose cable was pulled from the locker with such force as to not only part the bitter end, but fracture the bulkhead on which it was mounted. A major consideration is that such incidents are often associated

with personal injuries and even loss of life and is therefore a concern for ship owners and masters alike. It is an unfortunate fact

that many of these accidents have been caused by poor basic seamanship and failure to plan ahead. The advent of very large vessels such as VLCCs and bulk carriers has added to these concerns, where not only are the costs and

consequences of anchoring accidents that much greater, the technical challenge of anchoring such

large vessels is also greatly increased. It is therefore timely to review anchoring procedures and to see how the risk of accidents can be reduced. to a minimum.

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ANCHORING

EQUIPMENT

SPECIFICATION

for

150,000 tonne

deadweight ship

ANCHORING EQUIPMENT

2.1 THE

ANCHOR

The requirement of an anchor is to bite firmly into the sea

bed, provide enough holding power and to remain in the

right position without overturning even when pulled over

the sea bed.

The total mooring power of an anchor is the sum of the holding power of the anchor combined with the resistance created by the cable on sea bed. The cable also has an important role in maintaining the stability of the anchor. Maritime vessels are generally equipped with 11 to 14 shackles of cable, each shackle being 27.5 metres in length. The amount of cable paid out will vary according to the depth of the water and the conditions and this will be specified as part of the anchoring plan.

2 .

2 THE WINDLASS

Oamage to anchoring equipment and numerous personal injuries have been caused by incorrect use of the windlass. A typical example of misuse is the windlass motor [rather than the brake! being used to payout the cable. This may result in motor over-pressurisation causing excess internal surface to surface forces and then fracture of the motor casing. If the windlass brake is misused, the lining can in extreme cases actually catch fire, a situation often compounded by inadequate maintenance.

I

Cab le

"4"."M"9""'i't',In'

Spurli ng pipe

From the diagram, you can see that the only piece of equipment on board that is designed to take the full weight of the vessel is the bow stopper, with a rating of

480

tonnes. By contrast, the windlass motor has a lifting power of just 32 tonnes [3 shacklesl or 38 tonnes [4 shackles!' It is designed to lift or lower an anchor and three shackles of cable through a maximum of 82 meters of water in a

verticallift.l

6

I There IS a proposal by the lACS (Inter national AssocIatIon of Classlflcalion Societlesl that the windlass should be capable 01 lifting the anchor and

cable in 110 me r s of water The wind speed of 14 m/sec 128 knotsl. and a three knot current lunchangedl. at a speed of 0 ISm/sec 19m/mini

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The crew should have a clear understanding of the implications of any variation from the vertical [up-down] position of the cable while the anchor is being manoeuvred. Any angle out of the vertical indicates horizontal force that includes part of the ship's mass, which strictly speaking is not allowed for in the specification. Any changes in the alignment of the cable relative to the hull should be communicated to the bridge immediately so that the position of the ship can be altered to remove the load on the cable.

A 150,000 tonne deadweight ship has the following anchor equipment rated 'as new' according to the Classification Society rules:

LIFTING POWER OF ANCHOR WINDLASS 38 TONNES FORCE WINDLASS BRAKE HOLDING POWER 279 TONNES FORCE

CABLE STOPPER S,~FE WORKING LOAD 480 TONNES FORCE ULTIMATE TENSILESTRENGTH OF CABLE 600 TONNES FORCE

LENGTH OF

1

CABLE I SIDE 13 SHACKLES WEIGHT OF 1 SHACKLE OF CABLE 7.2 TONNES FORC E

WEIGHT OF 1ANCHOR 10.6 TONNES FORCE

Tankers are also fitted with two bow stoppers each rated at 200 tonnes force for SBMs.

2.3 PREVENTING

DAMAGE TO THE

WINDLASS MOTOR

AND CLUTCH

Whether electric, hydraulic or steam, the windlass is designed purely to control the weight of the anchor and three [or fourl shackles of cable. In particular, the windlass gearbox should not be used as a low ratio box as in a motor vehicle where the gears are used to slow its descent down hill. If the gear box is subject to such reverse forces, serious mechanical damage is likely to result.

Exceeding the designed limits of hydraulically powered windlasses will cause the system to become over pressurised. If bearing pressures within the motor are exceeded, metal will be shaved off its components. These shavings pass through the coarse filter and into the pump. Further increase in bearing pressure can cause the casing to crack. In such a situation, the veered cable cannot be recovered.

External forces applied to the valve/slide gear of steam windlasses will cause the drive to be driven. This can result in failure of the eccentric. The dog clutch may jump out of engagement due to the parting force at the dogs and the clutch operating fork will deform from its bed within the annular groove on the dog.

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Failure to insert the clutch lever securing pin will also lead to clutch disengagement. If the faces are badly worn, the clutch can jump out of gear even if the clutch operating lever is properly pinned because the fork is not sufficiently strong to resist the force pushing the dogs apart. The fork may also have become distorted.

2 .

4 PREVEN

T

ING DAMAGE TO THE WINDLASS BRAKE

The windlass brake, not the motor, should be used for paying out the cable. This is because the brake has a rated static applicable force some 10 times that sustainable by the motor. However, use of the brake relies heavily on the skill of the crew and the proper 'as new' maintenance of the brake mechanism. On larger vessels, the brake should always be manned by two crew members as the rated force cannot be applied by one man alone.

A NUMBER OF SITUATIONS WILL LEAD TO BRAKE DAMAGE

• Brake has been screwed up tight but the vessel's momentum causes it to slip

• Slipping causes heat generation and the brake to fade

• Heat causes the brake band to expand and so become less tight

• Heating by friction causes the brake to fade even more

LIKE THE MOTOR. THE BRAKE HAS VERY SPECIFIC DESIGN LIMITATIONS:

• The windlass brake is designed to control the cable running out and to stop it vertically without the ships weight on it

• The windlass brake is not designed to arrest the motion of the ship

• The windlass brake is not designed to hold the mass of the ship

Brake use should ideally be practiced a minimum of once a month for each windlass. Failure to do this will quickly lead to seizure of parts because sea water causes very rapid rust build-up. Talking through the procedure is also a helpful way to remind crew of the precise sequence of events. In an emergency, having the skill and ability to drop the anchor will save the day. Use of the motor rather than the brake could have insurance implications due to improper use of equipment.

The bow stopper must be engaged and the motor declutched when the drop is finished, with the cable in the up and down position. As you can see from its load specification, the bow stopper has 1.7 times the holding power of the brake and is the only piece of equipment that is designed to take the full load of the ship at anchor. However, in order to be effective, the bar of the bow stopper must lie on the horizontal link with the locking bar in place with no gap that could allow the tongue to lift, otherwise the bow stopper could ride over the vertical link when weight comes on the cable and distort the locking bar.

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PREPARING TO ANCHOR

Advanced planning and excellent communications

between the bridge and the anchoring team are essential

to safe anchoring. The master will ensure that the crew is

trained in the use of the anchoring equipment and has

access to accurate and up-to-date information about the

anchorage so that an anchoring plan can be prepared.

The master should select an anchorage that is sheltered, with good holding ground and an appropriate depth, depending on the ships own manoeuvrability and conditions. Weather and sea conditions and dangers such as submarine cables, pipes and wrecks should all be taken into consideration.

3 .

1 LYING TO A SINGLE ANCHOR

Although the method varies depending on the depth of an anchorage, lying at a single anchor is most frequently used because of its handling

simplicity when dropping and weighing anchor.

In this pattern the anchor is usually let go under very slight sternway. The ship 's speed is reduced according to the plan, the engine is stopped just before the anchorage and ships advances only by its momentum. The engine is put astern just before the anchoring point so that the ship stops at the intended spot. The anchor is let go just after the ship is dead in the water.

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VIOEOTEL P ODUCTIO 5 ANCHORING SAFELY

3.2 BASIC PROCEDURE

Here is the basic procedure for anchoring a small to medium size vessel:

BEFORE ARRIVAL AND AS PART OF THE ANCHORING PLAN

• Select the position of the anchorage and plan the approach

• Determine how to reduce the ship's speed from the initial approach to the intended anchorage

• Establish the depth of water, nature of bottom, which anchor to use and how much cable to payout

• Decide manning for anchoring including the personnel on bridge, engine room, fo'c'sle, pilot ladder or gangway if required

• Brief the anchoring team

SHORTLY BEFORE ARRIVAL

• Clear the anchors, hawse and spurling pipes

• Test the windlass and brake

• Test communications

• Prepare to display anchor signal. (ball daytime, lights at night]

ON NEARING THE ANCHfJRAGE, AMEND THE PI..AN TO INCORPORATE:

• Other ships in the anchorage

• Local weather and sea conditions

• Local navigation warnings and regulations

• Orders from the authorities

• Advice from the pilot or Vessel Traffic Services

APPROACH THE ANCHORING POSITION BY HEADING INTO THE PREDOMINANT FORCE IEITHER WIND OR CURRENT/TIDAL STREAM, USUALLY THE LADER)

TAKE WAY OFF THE SHIP AND THEN MAKE VERY SLIGHT STERNWAY

LET GO THE ANCHOR. CONTROLLING WITH THE BRAKE ONCE THE ANCHOR IS ON THE SEA BED AND SLOWLY PAYING OUT AS THE SHIP MOVES ASTERN

DISPLAY THE PROPER SIGNAL FOR A VESSEL AT ANCHOR AT NIGHT, SWITCH OFF THE STEAMING L1GH S

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KEEP THE BRIDGE INFORMED WHETHER THE CABLE IS TIGHT AND HOW IT

IS LEADING, tOR EXAMPLE "UP AND DOWN" OR '·TIGHT AND LEADING'

TELL THE MASTER HOW MANY DEGREES THERE ARE BETWEEN THE

ANCHOR AND THE BOW, SO THAT HE CAN ASSESS WHETHER THE

ANCHOR IS UNDER ANY STRAIN

WHEN THE CABLE HAS BEEN PAID OUT TO THE AGREED SHACKLE MAR K

['FOUR IN THE WATER ' "SIX ON DECK : OR SIMILAR!, THEN APPLY THE

BRAKE THE BOW STOPPER SHOULD THEN BE APPLIED AND SECURED

WITH THE PIN, THE SHIP SHOULD BE STOPPED OVER THE GROUND US IN G

THE ENGINE

WAIT FOR THE CABLE TO COME TAUT AND THEN SLACKEN TO SHOW THE

SHIP IS 'BROUGHT UP" (WATCH FOR THE CABLE GOING TAUT AND THEN

SLACK, TAUT AND THEN SLACK, OR JUDDERING WHICH MEANS THE

ANCHOR IS DRAGGING)

CHECK THAT THE BRAKE IS SCREWED UP TIGHT AND THE BOW STOPPER

SECURE.

SET ANCHOR WATCH ON THE BRIDGE AND SECURITY WATCHES

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VIDEOTEL PROOUCTIO S ANCHORING SAFELY

SECTION 4

, 1

I

,.~'

ANCHORING A VERY LARGE VESSEL

4.1 IS EQUIPMENT KEEPING PAC

E

?

While the general principles described for small to

medium sized vessels also apply

to

very large vessels

such as VLCCs, the

hazards

associated both with Laying

anchor and while lying at anchor are greater with a large

vessel, as are the likely consequences of any accidents.

It is a widely held belief that these failures are in part due to the specifications of anchoring equipment not keeping pace with the increasing size of vessels. However, an examination of classification

society specifications reveals this not to be the case. In the vast majority of incidents, accidents are related to a combination of inadequate

preparation for anchoring, poor seamanship, lack of communication between bridge and fo' c'sle, misuse of anchoring equipment and

inappropriate anchoring procedures. Concerns about the increased risks associated with anchoring very large vessels have led some companies to issue instructions to the effect that the anchor must be walked out all the way, regardless of the depth in which the vessel might be anchoring.

DESIGN

CRIT

ERIA -

EQUIPMENT LETTER

Derived from: f:...

113 ';'

2BH i

AIIO

Where: = SUMMER DISPLACEMENT IN TONNES B'= MOULDED BREADTH IN METRES

H= SUMMER FREEBOARD IN METRES

,I:J., = AREA OF THE PROFILf OF THE HULL IN SQU RE METRES

The various classification societies arrive at the equipment letter through the above formula which confirms that the design capabilities are directly related to the size of the vessel,

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VIDEOTEL PRODUCTIO S ANCHORING SAFELY

I

SECTION 4 ...

.

~

,

4.2 THE TRADIT

I

ONAL

FORE

& AFT (IN-LINE]

APPROACH

In the traditional in-line approach, where the anchor is

laid in line with the ship's fore and aft axis, walking the

anchor and cable back the whole way

is

permissible,

provided the cable is kept up and down

the

whole time and

that the design speed of the windlass is not exceeded.

While this is easy enough to say in practice, with a very

large vessel thiS is a difficult manoeuvre and risk of

damaging the windlass is relatively high

.

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SECTION 4

VIDEOTEL PRODUCTIOI S ANCHORING SAFELY

A WORST CASE SCENARIO

A vessel is to anchor in the traditional in-line method. The anchor is walked back just clear of the water, the engines are put astern and when the wake has reached the bridge wing the engines are stopped and the order given to let go. The cable is allowed to run freely as the vessel moves slowly astern. At eight shackles on deck the cable is snubbed and at ten on deck, the brake is screwed up tightly. Inability to arrest the vessel within the very small distance twixt up and down and bar taught results in a cable with no elasticity left. Even though the brake is screwed up tightly, the vessels momentum exceeds the brake's 279 tonnes resistance and the brake begins to fade. Fading causes heat generation which, through volumetric expansion, enlarges the internal diameter of the brake band, thus allowing more fading. Despite checking the astern motion, the motion of the vessel is too great and it continues to move astern. The brake band is now so hot it has expanded such that the cable is now accelerating . Before the

vessel can be brought to a complete stop, the three remaining shackles have been drawn from the locker. Detachment of the bitter end or certainly deformation of the chain locker is likely to follow.

The momentum of the cable and its direction of motion are such that the cable will leave the gypsy and arc above it. When the end finally parts, energy within the cable is quite sufficient to punch a hole through 20mm plate and carry away any deck fittings in its path.

Given that putting out 10 shackles with the motor takes in excess of half an hour at 5cms per second, it is exceedingly difficult, especially with larger, diesel-powered vessels, to control sternway to such a fine degree. The long period of time required to payout the anchor cable sometimes leads to masters using less cable than they should. There have been incidents where this has lead to anchor dragging and consequent

grounding. Even the most experienced master may run into difficulties and this is because the traditional approach to anchoring already places him at a mechanical disadvantage.

Take the example of a vessel anchoring in 50 metres of

water with 10 shackles:

The difference in horizontal distance between the position of the vessel when the cable is up and down and if, it became bar taut would be approximately 50 metres. Now, a 150,000 tonne vessel has a beam

approaching 50 metres. So the challenge is easy to visualise; the master is trying to stop a ship of say 300 metres within a distance roughly equal to its beam.

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VID OTEL PRODUCTIO NS ANCH ORIN G SAFELY

SECTION 4 ANCHOR ON SEABED

T

HE TRADITIONAL FORE &

AFT

(

IN-LINE) APPROACH

~ ~ ~ TIDE AND WIND

The engines should be used to take sternway off the ship. Failure to halt the

astern movement will result in a bar

taut cable with no elasticity left because all the catenary has been taken up. The

full mass of the ship comes onto the windlass. The force now being exerted on the windlass is now about 1000 times maximum allowed l

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VIDEOTEL PRODUC-IIONS ANCHORING SAFELY

The force required, at

the

stern,

to

')

IE

the

vessel in a straight

line is approximately

three times that

required to

TU

RN

the

vessel by applying a

force at right angles

to the stern

AN ALTERNATIVE APPROACH TO ANCHORING

5 .1

T

HE U

-

TU

R

N METHOD

The U-turn or more precisely, orthogonal method of anchoring has a long

historical precedent and has been the practice of a number of masters for

many years. Its benefits have also been discovered during emergencies

when the master's quick reactions and knowledge of how to lay anchor on

the move have

saved

the day. However, prior to the mathematical and

mechanical analysis carried out by Captain Allan McDowaW, such a

procedure could not become mainstream and owners would have been

reluctant to incorporate it into their operational procedures

.

The procedure is not without risk and its success depends on the crew

having a clear understanding of the procedure with appropriate training in

the use of the equipment. Because timing is critical, excellent

communications must be maintained between bridge and fo·c'sle. Masters

and crews who have not used this method before

should

ensure that

adequate sea room is available. With experience however, the manoeuvre

can be safely completed within a relatively compact area.

5. 2 AXIA

L

VERSU

S

ROTATIONAL FOR

C

E

S

The secret of the U-turn approach to

anchoring lies in separating the momentum of

the

ship's

hull from the forces necessary to

control the movement of the cable.

Consider a block shaped vessel, it has a block

coefficient of 1. The force required to

accelerate the vessel in the fore and aft line is

three times that required to rotate it about

its

pivot point

. That is why it is easier to push a

small sailing boat sideways or rotate it round

its axis than move it in the fore aft line.

It follows that to decelerate the

same

block in

rotation would be one third the force required

to stop its axial momentum

.

TURN a stationary vessel

Force r"qulrecl 10 ID!~E.

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VIDEOTEL PRODUCTI ONS ANCH ORING SAFELY

This difference is because rotational inertia is less than the axial inertia; it is a change from straightforward linear acceleration to one of angular acceleration. A further contributory factor is that in the latter, the distance from the axis of the centroid is part of the overall equation, whereas in the former the distance from the axis of the centroid does not enter into the equation.

However, a ship is not a rectangular block in plan view, but a diamond or lozenge shape. Taking this as the best fit shape, the block coefficient is not 1 but 0.5. The radius of gyration of the new shape is now one third that of the full box shape.

Since the radius of gyration is part of the equation which gave a one third reduction in force required to decelerate the box shape, then it follows that with a block coefficient of 0.5, the reductions is now one ninth. But the mass has now been halved, so the factor of 9 must also be halved, giving a final figure of 4 1/2. Thus for a block coefficient of 0.5 the reduction factor is 4 1/2, whilst for a block coefficient of 1, it is 3. The ship shape lies somewhere between these two and can be assumed to be equal to 7/2.

Instituting a turn at the point where the anchor is let go will change the force on the cable from one of axial translation to one of rotational translation. But one of the factors of rotational inertia is the distance from the axis through the centroid. By using the anchor and cable this distance has now been increased by the length of the cable, a factor of 6.5. By applying the two factors [7/2 X 13/2J one finds the force on the cable is approximately 23 times less than the original case l

Clearly, keeping the cable at right angles to the hull greatly reduces the likelihood of extreme forces being applied to the anchoring equipment which is why the U-turn method is very much safer and is associated with far fewer accidents. When the cable is at 90 degrees to the fore and aft line, fore and aft movement does not affect the tension of the cable, or only minimally. In this way, it is very difficult to exceed the forces that one is trying so hard to avoid with the fore and aft method.

This technique is also more forgiving should the master have misjudged the speed and is moving too fast and especially in the event of engine failure during the anchoring procedure. This is quite impossible using the traditional, fore and aft method. Having the skill to anchor a vessel which is moving is one that can save the ship, possibly your life and your job!

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USING THE U-TURN METHOD

The anchor and gear is prepared as for any normaL

anchoring. The windLass is tested in both directions, the

Locker checked for obstructions, the dog clutch engaged,

the anchor walked out clear of the hawsepipe, brake on,

bow stopper/compressor on and clutch out. The master

shouLd always take personal responsibility for these

checks.

6.1 OPERATIONAL BRIEFING

Before the anchor is to be let go, there need to be two pre-operational

briefings. The first briefing is a training session to ensure that the

personnel concerned know exactly how the equipment works and should

be used. The second briefing is just before anchoring, to ensure that the

crew understands that

:

SECOND BRIEFING :

• On large ships there should ideally be two men on the brake since

the rated force cannot be applied by one man alone.

• The anchor will be lowered under power to an ordered number of

shackles on deck, say two, prior to taking out of gear and letting go

.

on the brake.

• When the cable is released, the cable will be let out in a controlled

manner so that each !.ink can be followed with the eye.

• The cable is kept running out until the desired length is all out,

which avoids the brake fade caused by the more common practice

of stopping and starting.

• When the cable is out at the desired length, the cable is stopped

from moving by the brake then the bow stopper is put on. The safe

pin is fully engaged whilst the cable is stopped and still vertically

up and down

.

• When the bow stopper is on, the bridge is to be kept informed of

the direction of the lead on the cable which must be kept on the

beam until all movement has ceased

.

Only then can the cable be

allowed to draw slowly ahead

.

If the bottom is known to be very deep, or particularly rocky

,

it would be

prudent to walk the anchor out until just clear of the seabed.

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TIDE AND WIND

Approach downwind/tide with

J,

minimum steerage way of 2-3 knots.

U

J,

_{Hard a·starboard.}

Dead slow ahead.

J,

Allow full scope to pay out in one controlled movement. Appty brake

and compressor

Short bursts of ahead

or astern power to keep

the lead as near

perpendicular to the

forecastle as is

possible. Short bursts of power

to control drift. Vessel

bought up . Cable in

shallow bight on seabed.

Only sideways drift _{( f t oP engines}

Let go starboard anchor Observe sWing 1350 _{off course, all forward}

\ \

~- ~o

''''''

5<.,

'"9'""

a."

co"'''

\\)v

V(

Tension in the cable now snubbing the bow and the vessel

is drifting astern under wind/tide.

r

Sl.w."",

6 .

2 APPROACH TO ANCHORAGE

The objective is to let the anchor go with the bow moving sideways over the sea bed at about 0.5 knots. The actual speed of the bow may be much greater by this method and the manoeuvre has been successfully

accomplished by Captain McDowall at speeds of up to 4 knots ahead whilst turning. The turn will always stop the ship. In cases where you cannot afford to wait, some forward speed can be accommodated, provided the cable is kept on the beam. The sideways movement is very slow.

Using the reverse of the normal approach, steam the vessel into the anchorage downtide/wind with minimum steerage way, that is with engines stopped and steerage being maintained by short bursts of ahead power. When nearly abeam of the desired position, put the helm hard over and give a kick of Dead Slow Ahead. Only at this point should the bow stopper/compressor be removed.

Once the swing has started and the vessel is seen to be turning the correct way, take care because wind on the accommodation block can cause the vessel to swing the opposite way, the engines must be rung down to Stop again. When the heading has changed by about 45° put the

engines Slow Astern. The duration of this burst should only be sufficient to

take off the forward motion, it is not to get the vessel moving astern. If the vessel is fine lined, the astern movement will have the effect of making the turn tighter. However, this engine movement is usually unnecessary because the act of turning and the ship's projected underwater side area stops the ship after a turn of around 120 degrees.

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By the time the vessel's heading has changed by 90° the greater

component of its motion will be sideways with only a very small proportion being in the forward direction. At 135°, all forward motion should have ceased and the vessel will only be experiencing a small sideways drift. A short kick Slow Astern may be required to ensure this. The anchor is let go in one controlled operation, allowing the full scope to be payed out in one movement. The brake and compressor are applied along with safety locking pins.

The vessel will continue its sideways drift and draw the cable along the seabed at right angles to the fo'c'sle. Communication between bridge and fo'c'sle are paramount to the success of this manoeuvre as the fo'c'sle officer must keep the bridge informed of the direction of lead. Short kicks of ahead or astern are given as required in order to keep the lead at right angles to the vessel.

Eventually the tension in the cable will snub the bow and start to turn the vessel towards her cable; at this point it may be necessary to use engine movements to control the rate of turn. As the vessel points on her cable the effect of the wind/tide will initiate astern motion, again it may be necessary to check the effect of this by use of engines.

By the time the vessel is laying head to tide/wind the cable will have been drawn out in an arc on the sea bed and will be acting as an additional shock absorber.

Once you are accomplished in this manoeuvre, the speed of approach may be increased just so long as the corresponding astern movement at the commencement of the turn is also increased. This will not only have the effect of reducing the forward motion more quickly but will also reduce the radius of the turn.

TRIED AND TESTED

This manoeuvre has been tried and tested on a number of different types and sizes of vessel. It takes approximately 12-15 minutes from initiation of turn to bow stopper on . On one occasion it was performed in an

emergency due to main engine failure when the vessel was preceding

.downtide at a speed of 12 knots. One company which had previously been plagued by accidents, incidents and dangerous occurrences has been using this method for some five years and since then has not had any further incidents of failure of anchor gear or other unsafe occurrences whilst anchoring. However, it is for individual operators and their masters to assess the most appropriate method of anchoring for their vessels and this technique is described here purely as an alternative approach which may have benefits in certain circumstances.

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ANCHOR WATCH AND SECURITY

The main purpose of anchor watch is to keep the vessel

safe at all times. In particular, it will be necessary to look

out for signs of anchor dragging such as a swinging

motion of the ship, the ship moving sideways, weather

side constant, cable vibrating. cable constantly taut and

positional changes relative to nearby ships.

The ship's position should be monitored by whatever means possible and the master informed if the ship moves outside the scope of the cable. If anchoring in silt, it may be necessary to weigh and let go anchor every day or so. It is also important to keep a lookout for any craft approaching or people seeking to come on board to ensure that they are legitimate visitors, following the procedures set out by the company in accordance with the International Ship and Port Facility Security Code [ISPS Codel.

WATCH KEEPING DUTI ES :

• Monitor ships position

• Maintain continuous effective lookout

• Ensure suitable fire/piracy controls

• Monitor effective communication internally and externally

• Check anchor and cable are ranged correctly

• Ensure correct signals are displayed at correct times

• Note tide and flow changes

• Ensure vessel complies with COLREGs [Regulations for Prevention of Collisions at Sea, Rule 30 Anchored vessels and vessels

aground]

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WEIGHING ANCHOR

Weighing anchor requires similar preparations to

anchoring, in particular making sure that all the

equipment is functioning properly and that the working

space around it is clear and safe.

Power supplies to the windLass must be switched on and checked and the proper functioning of the clutch and brake tested, whiLe the cabLe is held on the bow stopper. The chain locker, spurling pipe and hawse pipes shouLd be checked . Communications with the bridge should also be tested.

It must be remembered that the windLass is designed for a vertical lift of one anchor plus three shackles (or 82 metres] of cabLe. If the anchor is leading out of the verticaL, this may cause damage if forces in excess of these limits are applied. The ship's engines and heLm can be used to bring the cable as near vertical as possible.

When instructed to do so, the windlass should be put into gear, the bow stopper released with the stopper removed before the brake is released. No weight must be on the stopper when the locking bars/pins are removed or a serious accident could ensue. Again when instructed to do so, start to heave away, making sure the cable is clear and not fouling the ship's structure, hosing off the mud and debris as the cable comes in.

Normally, the cable washers in the hawse pipe will clear any mud from the anchor. If the cable is heaviLy coated with clay, then heaving more slowly usually does the trick. Failing that, a powerful hose should be used.

If the anchor has picked up a cable or other obstruction the windlass should be stopped immediately and the bridge informed.

If everything is normal, reports should be made to the bridge of how the cable is leading, when it is clear of the sea bed, [this may not be obvious if the cable is already vertical! and when it is clear of the water.

The anchor ball should be lowered or anchor Lights switched off when the anchor is weighed.