711

1 INTRODUCTION

Working with mooring lines entails an inherent risk

of accidents [5], notably in case of mooring lines

breakage and their subsequent snap-back

phenomenon; that is, the sudden release of the stored

energy in a tensioned mooring line when it suddenly

breaks [13], [10]. A fact that is corroborated in

multiple accident reports [1], [3], [4], [8], [9]. One

example of their seriousness is reflected in UK P&I

(2016) [15] study where, through a statistical analysis

data along the last twenty years, it is shown that

personal injuries of this type is the seven most

frequent cause, but the third expensive per claim,

indicating how appalling some of them can become.

In the past (even being normal in small ships

nowadays), to moor a ship it was necessary to deploy

lines conventionally in warping drums by pulling the

tensioned line after taking sufficient turns so that

there was enough friction for the rotating drum and

then stoppering to allow the free end to attach to the

bollards.

Contemporary mooring practice on modern large

vessels, as it makes manual handling difficult,

demands that all lines are set up on dedicated and

self-stowing mooring winches that, on the same

driving shaft (forward, in combined windlass-

winches also), allows deploying them usually from

two or three drums, each one fitted with independent

capability to be engaged-disengaged. In most of those

ships, the drum is of the split (recommended by ISO,

2012) [6] instead of the undivided type and the brake

is of the band type [2], [10], [16] although the disk

brakes option has advantages as they are less affected

Spring-loaded Winch Band Brakes as Tools to Improve

afety During Mooring Operations on Ships

S. Igle

sias-Baniela & J.M. Pérez-Canosa

University of A Coruña, A Coruña

, Spain

. Cid-Bacorelle

Navantia Ship Repairs Fene

-Ferrol, Fene, Spain

ABSTRACT: Some recent accident reports involving large vessels in mooring operations or breaking away from

their moorings conclude that brakes of mooring winches do not render before line parts. As the potential loss of

life is high, the utmost attention on-board must be paid to minimise this inherent risk. When the load on the

mooring lines becomes overloaded beyond the pre-set levels, mooring winches band brakes have the safety

function of rendering and allowing the line to shed this load before its potential breaking and the subsequent

snap-back. As a preventive measure against breaking, the pre-set level, known as Brake Holding Capacity

(BHC), must be below the Minimum Breaking Load (MBL) of the line. In this paper, the authors analyse

concerns that can arise from those with conventional screw manually-applied band brakes regarding their BHC

reliability. Thus, in order to improve safety, the advantages of the spring-applied band brakes with manual

setting and release or with hydraulic release are highlighted. Finally, the paper shows a typical procedure using

a hydraulic jack for brake testing the winch of a Liquefied Natural Gas (LNG) ship to fix their BHC in order to

hold 60% of the MBL of the mooring line.

http://www.transnav.eu

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 14

Number 3

September 2020

DOI: 10.12716/1001.14.03.

712

by wear and tear and the line can be reeled paying out

irrespective of the top or bottom of the drums;

probably due to acquisition and maintenance costs

“… few, if any, winch manufacturers offer them as an

alternative to band brakes” [10].

A split-type drum comprises a tension section that

holds one layer of the mooring line and a storage

section that the remainder of the rope is wound onto.

They were designed to cope with two disadvantages

that undivided drums have:

− To prevent the spooling problem encountered with

undivided drum winches due to lines biting into

each one when under load (undivided drums have

several layers on one drum, whereas split drums

have one layer on the tension section), and;

− As on undivided drums all the line required for

mooring the ship is stored on a single drum, the

layers of the unused line increase the diameter of

the drum effectively, thus decreasing the BHC

whereas, as split drums operate with only one

layer of the mooring line on the tension section,

theoretically they can maintain a constant BHC.

Each drum has its respective band brake that lets it

hold mooring lines fast on brakes with the winch

disengaged, after being previously heaved tight

against the rubber fenders with the winch engaged

until achieving the desired pretension to use friction

in order to reduce the fore and aft movement of the

vessel [2], [10].

Brakes have two circular steel bands connected by

an articulated joint pin. At the opposite end, the top

half is anchored to a pivot point fixed to the deck or

bed plate and the bottom half (the free or floating

end) is connected to the brake control lever (Fig. 2).

Brass screws or copper rivets attach steel bands to

high-grade non-asbestos marine brake linings. Due to

the wear and tear in ordinary use of brake linings,

when their thickness has reached a certain level they

must be replaced as per manufacturer´s operations

manual (it usually features a wear indicator to this

end), in order to maintain effectiveness of the winch

brake by suitable friction between the linings and the

rim of the winch drum. The brake linings rely on the

coefficient of friction against the brake drum to hold

the force on a line. How to tight or release the band

brakes depends on their application type, either by

means of a simple conventional brake handle (or hand

wheel) manual screw or in conjunction with a spring-

applied by manual setting and release or by hydraulic

release.

As a static device, the prime aim of the band brake

is to secure the winch drum and the mooring line

spooled and layered on it, holding the line tight when

moored.

When the load on the mooring line becomes

excessive (overloaded) beyond a predetermined level,

the brake has an added safety function of rendering to

allow the line to shed its load by releasing the tension

in a controlled manner [14]. This serves to prevent a

mooring line from breaking and snapping back.

To manage the safety function of the brake

effectively, a winch brake test for the winch operator

guide should be carried out in order to hold the line

correctly with the winch disengaged. However, the

load at which the brake renders is also dependent on

its actual condition.

At the ship design stage [10], the MBL of the lines

is determined taking into account factors such as the

ship’s size and hull form, the number of mooring lines

to be deployed, mooring restraint requirements, the

maximum windage and lateral underwater area to

cope with wind and tidal conditions respectively.

Regarding the windage and underwater area, Oil

Companies International Marine Forum -OCIMF-

uses standard environmental criteria to this end [10].

Based on the MBL, the mooring winch general

requirements and parameters being dealt with in ISO

3730:2012 [6] and ISO 7825:2017 [7] are determined.

Regarding the winch brake, their BHC will not be less

than 80% of mooring line MBL [6] in the first layer

although, through a brake winch test, it should be

operationally set to hold 60% of the MBL on the first

layer to permit slippage before the line breaks [11].

The mooring set-up on-board should be such that

the winch brake should be the weakest link in case of

overload followed by the primary line, the synthetic

tail if any (MBL for mooring tails should be 25%

higher than that of the primary mooring line to which

they are attached [10]); and lastly the fixed structures

such as the winch foundation and the fairleads. This

set-up is the standard and its intention is to minimize

the consequences in case of overload.

The drum load of the winch (also called hauling,

hoisting or rated load), i.e. the pull that the mooring

line can develop at the rated speed on the first layer,

should be within 22% to 33% of the MBL of the line

[6] assuring adequate force to heave in against

environmental forces, but being low enough to

prevent the line from overstressing in the stalled

condition i.e., the maximum rope tension, in

kilonewtons -kN-, is measured at the drum exit when

the drum ceases to rotate in the haul direction, the

prime mover being set for maximum torque and the

rope being wound on the drum in a single layer. The

rendering load (maximum rope tension measured at

the drum exit when the drum just starts to rotate in

the opposite direction to the applied driving torque)

will not be more than 50% MBL of the line [6];

therefore, the BHC is always greater than the

rendering load. Thus, when occasionally

unanticipated changes of load generated by extreme

winds, waves or tide cause the brakes to render and

the vessel to be at risk of moving off the berth, it is not

possible to engage the winch and haul the lines after

releasing the brakes in an attempt to put the ship

alongside again [11]. Instead, good seamanship in

those cases dictates to maintain engines ready for

manoeuvring, to require tug assistance, to ballast the

ship down to reduce the total forces acting on the ship

as the wind gradient is greater than the under keel

clearance effect [11] and to disconnect hoses or any

other fixed cargo handling system on-board from the

harbour.

As most modern large ships are equipped with

dedicated mooring winches with split drums fitted

out with band brakes, in this paper we analyse how to

manage the safety function of the band brake to

render before breaking the line and their reliability

depending on the type of application. To that end, the

713

methodological approach followed by the authors

along this work combines the theoretical background

to highlight good seamanship on this subject with

empirical evidence on a shipyard obtained by actual

cases on board different ships. This strategy allows

them to compare the efficiency of distinct winch brake

types and to show a real study case carried out on

board an LNG carrier, having mooring winches with

state-of-the-art technology.

2 PERFORMANCE DETERMINANTS OF BAND

BRAKES

The load at which the brake renders depends on

several factors which, as a whole, determine their

performance. The degree to which it has been

tightened, their condition and the correct direction to

reel the line on the winch drum are examined below.

2.1 The setting of the band brake

After hauling the line with the winch engaged until it

achieves the correct pretension, the degree to which

the brake linings has been tightened against the rim of

the drum to hold the line with the band brake and the

winch disengaged is the primary factor. The tension

force generated by the threaded screw spindle

engaging into the nut creates a compressive force of

the brake band against the rim of the barrel through

the brake mechanical linkages [16] which will

generate a resistant torque. To this end, the winch

operator should have some form of reference guide

by a winch brake test to try and ensure constant

torque each time the brake is applied (further on we

will analyse an example of how it should be carried

out).

2.2 The condition of brakes to maintain proper friction

The actual state of winch brakes affects their friction,

so a small change in friction coefficient causes a big

change in the BHC of the winch in such a way that, as

a rule of thumb, it may be twice [10]. The condition of

brake linings, the rim of the drum and a proper

maintenance of brake mechanical linkages are very

sensitive to changes in friction. The pitting and

corrosion reduce the brake’s effectiveness as the

contact area between the brake lining and the brake

drum metal face reduces.

As oil or heavy rust around the brake linings and

drum reduce the BHC of the winch, some operators

heave the drum engaged for a while with the brake

slightly applied in order to burn them off [5], [10]. The

same should be made to seating brake linings and

smooth them when replaced because they do not have

their full coefficient of friction due to their initial

rough surface. In both cases, the drum should be

turned slowly in order to prevent brake fade (loss of

friction) due to the overheating linings.

In order to avoid corrosion problems on the rim of

the drum on which the brake lining acts, it is

recommendable to make them either of stainless steel

or retrofitting the existing ones by machining the

drum rim and filling with solder of stainless steel

(Fig. 1) or even by welding a stainless steel plate over

the existing material.

Figure 1. Split drum of a dedicated mooring winch whose

rim was retrofitted by filling stainless steel with automatic

soldering in Navantia Ship Repairs Fene-Ferrol (Spain).

2.3 The direction of reeling on the winch drum

The mooring line should be correctly reeled onto the

drum; otherwise, a substantially BHC reduction of the

winch will occur. To avoid misunderstanding, it

should be permanently marked on the drum [5].

The criteria to establish the correct reeling of the

line on the drum should be such that, in the pay-out

direction, the mooring line pulls against the fixed end

of the brake band, closing the gap between the fixed

and the floating brake mountings and thus assisting

with the operation of the brake [2].

LoweringHoisting

Cheek plate

Anchored end

of the brake

Brake handle

lever

Floating End of

Brake Mounting

Brake Band

Joining Pin

Fixed Brake

Mounting

Paying Out Direction

of Mooring Line

Brake Pad

Brake lever

Nut

Drum rim

Figure 2. Correct reeling direction of mooring line

depending on brake mechanical linkages set-up. In this case,

it is achieved when it pays out from the top of the drum.

714

Lowering

Hoisting

Figure 3. Left: Line being incorrectly reeled onto an

undivided drum considering the brake mechanical linkages

set-up. Right: Drawing showing how the mooring line

should be reeled so that it pays out from the bottom of the

drum not from the top.

Fig. 2 shows how the line should be reeled

depending on the brake mechanical linkages set-up

(the parts that are used to link the band brake parts to

each other and to the bed plate). In this case, the line

should paid out from the top of the drum. Fig. 3

shows a line incorrectly reeled on an undivided drum

and how in this case, as the brake mechanical linkages

set-up is different, the line should be reeled so that it

pays out from the bottom of the drum instead of from

the top. Besides reduction of winch BHC, additional

problems may arise when the line is improperly

reeled because, as it does not work horizontally to

pedestal roller and fairlead, a risk of jumping from

the pedestal roller is generated.

3 MOORING WINCH WITH CONVENTIONAL

SCREW MANUALLY-APPLIED BAND BRAKE

With this type of application, the band brake is

tightened or r eleased by manually turning a screw

spindle by means of a brake handle (or hand wheel),

which is easy to apply (Fig. 4).

As a general rule, the winch operator should turn

the brake handle clockwise when tightening. Thus, as

a result, it draws the ends of the brake bands together

by closing the distance between the nut and the brake

lever (decreasing the effective control rod length),

which in turn brings the brake lining into contact with

the rim´s drum.

In order to achieve the proper torque to hold the

line, the brake is applied by tightening the screw with

the brake handle until some form of predetermined

index mark is in line with an indicator ring fixed on

the spindle-rod. Regarding the reliability of this

manual band brake application two problems may

arise:

1 Due to the wear of linings after some mooring

manoeuvres, if we tight the band brake until the

predetermined mark is set, the torque applied will

be less than the correct BHC of the winch (60%

MBL).

2 Under worsening environmental conditions, if an

additional load is applied to the attached mooring

line, the brake band stretches in the pay-out

direction. This reduces the load on the brake

controls relieving some of the tension in the

threaded rod until it becomes looser in such a way

that it could be possible to re-tight the brake when

the mooring line is under high load, even if it was

set to the correct torque originally. Therefore, with

those manually-applied band brakes, once the

winch is subjected to a high line load, there is no

way to determine the proper brake handle torque

required. So, retightening as brake band stretches

could be misleading because the operator cannot

be aware when he exceeds the maximum BHC

threshold and, therefore, the line may part before

the brake slips.

It could be possible to set the winches manually

with a torque wrench but few owners, if any, use this

option.

Figure 4. Conventionally screw manually-applied band

brake of Crude Oil Tanker “Tulip”.

4 SPRING-APPLIED BAND BRAKES

With band brakes manually operated by just screwing

up the brake handle it can be difficult to achieve the

required torque consistently in practice so that it

accomplishes their safety function. To overcome this

uncertainty, some brake designs incorporate a spring-

applied device with manual or hydraulic release. The

purpose is twofold: to assure a constant BHC of the

winch by applying a pulling force of the band brake

against the rim of the barrel that can be set up for

operator reference and to prevent the risk of

overtightening the brake band in case it stretches.

The band brake is spring-applied to hold on the

brake using a spring compressed inside a cylinder

against a piston that is part of the brake handle-

spindle-rod device. To release the brake, the piston

that compresses the spring needs to be either

manually or hydraulically operated.

The spring design is made of Belleville washers

(also known as “disc spring” or “Belleville disc”). The

theory behind this spring type [12] goes beyond the

content of this paper; suffice it to mention that it is a

conical-shaped spring with an open centre (much like

a washer) exhibiting low deflections relative to high

loads, making it ideal for cushioning heavy loads

with short motion. Their load/deflection ratio can be

changed by using several Belleville washers stacked

to modify the spring constant or the amount of

deflection either in series (aligned in opposite

directions to increase deflection and lower spring

constant) or in parallel (aligned in the same

direction to increase load maintaining spring

constant) or a combination of the two alignments. The

relationship between the load and deflection is non-

linear, particularly as load increases; therefore, they

are well suited to areas with constant thrust that must

stand up against heavy wear, as is in the case of band

715

brakes of mooring winches. The exact configuration

depends on the BHC of the mooring winch

requirements determined on ship design stage, taking

also into account the stroke of the spring regarding

their axial compression limits between the band brake

on and the releasing conditions. Fig. 5 shows

schematically a spring applied band brake formed by

Belleville washers where, depending on the manual

or hydraulic release, the piston compressing them is

displaced axially by the operator turning the brake

handle or by the hydraulic pressure acting on the oil

chamber respectively.

4.1 Spring-applied brake with manual setting and release

To apply the brake, the operator should have an

indicator ring that may be moved on the spindle-rod

device, whose correct position is set up through a

brake winch test as a guide to permit slippage before

the line breaks (it should be adjusted if required using

an Allen key). The degree to which the spring is

compressed inside the cylinder by turning the brake

handle depends on the holding load of the brake [10].

As the BHC of the winch will not be less than 80% of

the mooring line MBL in the first layer, but

operationally set up to hold 60% of the MBL, the

spring should have some residual compression

capability even in the brake-on condition set-up.

To release the brake once the winch is engaged, the

operator further decompresses spring against the

piston by continuing turning the brake handle

anticlockwise. In this way, distance “b” is increased

(brake handle-spindle-nut-rod-piston unit moves

toward operator) which consequently makes the two

half-circular parts of band brakes stop doing contact

with the rim of the barrel as a result of the brake

mechanical linkages set-up; i.e. the band brake

releases. To apply the brake from the released

condition, distance “b” decreases as the spindle

threads over the nut while the operator turns the

brake handle clockwise (Figs. 5 and 6). After an initial

compression of the two half-circular parts of band

brakes seating the linings to the rim of the barrel,

distance “b” stabilizes and the piston begins to

compress the spring until the indicator ring is placed

in line with the pre-set mark. In this way, the brake

can be applied regularly to its correct value because

any wear of brake lining and/or elongation in the

brake mechanical linkages is fully compensated.

Adjustment of

brake holding

power by turning

hand wheel

Adjus tmen t of

brak e h old ing

power b y tur ning

hand wh eel

Direction of load

Tightening direction of

brake band

Figure 6. Spring-applied band brake with manual release.

Source: TTS Kocks GmBH, Bremen.

Figure 7. Spring-applied band brake with manual release of

LNG Tanker “Excelsior”.

4.2 Spring-Applied Brake with Hydraulic Release

In this case, the brake is released either by a hydraulic

hand pump (Figs. 8 and 10) or, if the winch is

hydraulically powered, by taking advantage of the

main hydraulic pressure that drives it (Fig. 9).

With this band brake application, the operator

does not usually need to use the brake handle to

apply the brake or release it. Therefore, this design

option permits a more reliable pre-setting.

SLEEVE

B ef ore operation

adjust the

brake by t urni ng the hand

whe el so t hat t he a rr ow

l in e w it h t he groov e

PISTON

INDICATOR RING

BRAKE HANDLE

NUT

BELLEVILLE SPRING

WASHERS for axial load

ROD

CYLINDER LINER

HYDRAULIC SEALS

CYLINDER COVER

O-RING

NUT

CAP NUT

OIL CHAMBER K

(in case hydraulic release)

BACK CYLINDER

COVER

GREASE

NIPPLE

Connection

rod M

PILOT TUBE

SPINDLE left hand

thread

TOP OF CYLINDER

SLEEVE

Plate for adjustment of

BHC by turning

brakehandle

Figure 5. Spring-applied brake (Belleville washers) showing the band brake applied (brake handle-spindle-nut no to scale).

In this Fig., the spring is formed by 32 Belleville washers stacked in series. Source: TTS Kocks GmBH, Bremen.

716

The set-up in the brake on condition to fix 60% of

MBL of the line on the first layer by the residual

compression of the spring is achieved in the brake

winch test by turning the brake handle accordingly in

a similar way, as seen for manual release in the

previous paragraph. After this set-up, the brake

handle should be secured with a seal to prevent

tampering (Figs. 8 left and 9 right). However, for an

easy visual check, it is also recommendable to follow

the indicator ring-index mark on the fixed plate for

adjustment method (Fig. 15) seen for manual setting

in the previous paragraph [10].

The brake handle only serves:

− To adjust the spring residual compression through

the band brake set-up test;

− To turn it clockwise when we apply the brake on

after a visual check in case the indicator ring and

the fixed mark pre-set are not in line and;

− For emergency, releasing the brake in case of a

hydraulic breakdown.

Figure 8. LNG Tanker “British Innovator”: Band brake

spring-applied and hydraulically release by hydraulic hand

pump.

To apply the brake from the released condition, the

hydraulic pressure is relieved from the cylinder oil

chamber to the sump tank of the pump by opening

the oil return valve (Fig. 10). Thus, according to the

brake test set-up, the compressed spring

automatically extends until its compressive force is

balanced by the resistance of the brake band being

pressed against the rim of the barrel (Fig. 5 -distance

“b” decreases). Therefore, the spring automatically

applies the correct force between the brake band and

the rim of the drum at all times, which involves an

advantage over manual setting because there are not

any requirements for a crew member to re-apply the

torque by turning the brake handle to the pre-set

mark.

To release the brake, hydraulic pressure is applied

on the oil chamber to the other side of the piston

(pressure side) after closing the oil return valve by

pumping oil from the hydraulic hand pump (Fig. 8)

or, when the main hydraulic pressure that drives the

winch is used, by acting on the directional control

valve to this end (Fig. 9). By doing so, the spring is

further compressed until the linings are free from the

rim of the barrel (Fig. 5 -distance “b” increases).

Figure 9. Tanker “Florida Voyager”: Band brake

spring-applied and hydraulically released by taking

advantage of the main hydraulic pressure on winches

with hydraulic drives.

Adjustment of

brake holding

power by turning

hand wheel

Adj ustm ent of

brake holding

power by turning

hand wheel

Direction

of load

Tightening direction of

brake band

Hydraulic hose

Lever

Hydraulic

Hand Pump

Hydraulic Scheme

Figure 10. Spring-applied band brake with hydraulic (hand

pump) release. Source: TTS Kocks GmBH, Bremen.

5 STUDY CASE

5.1 Procedure for band brake testing a mooring winch

To ensure safe mooring, all mooring winch brakes on-

board should be set to release the mooring lines at the

correct load. To this end, brakes should be tested

individually at regular intervals, not exceeding twelve

months and after a retrofit or repair or when a brake

slippage or malfunction occur [5], [10].

This test is performed by means of a brake test kit

that consists of a hydraulic jack with a pressure gauge

and a bracket specifically made to bolt onto the flange

of the winch drum with a sliding pin, in order to

transfer the jack force to the drum.

In this paragraph, it is described the procedure for

a winch brake test in one of the winches supplied

with split drum having a band brake spring-applied

and manual release (see Figs. 5-7) of the LNG Tanker

“Golar Winter” carried out in Navantia Ship Repairs

Fene-Ferrol (NW Spain).

To carry out the test, data known, the ones to be

computed and their nomenclature (Fig. 11) are as

follows:

MBL of wire rope = 124 tons.

F1 BHC (required to hold 60% of MBL) = 74.40 tons.

L1 Distance drum centre - 1st. layer of rope centreline

(R+r) = 32.20 cm.

717

F2 Force exerted by the hydraulic jack (to be

computed).

L2 Distance centreline of drum to centreline of

hydraulic jack = 85.00 cm.

R Drum radio = 30.00 cm.

r Wire rope radio (1st layer) = 2.20 cm.

A Hydraulic jack effective piston area = 50.27 cm

P Hydraulic jack slipping pressure in bars (to be

computed).

The kit placed on board for use was the hydraulic

jack YALE Aluminium mod. AJH-660 (capacity = 60

tons and stroke = 152 mm).

The hydraulic jack fixed to the drum end plate

substitutes the pull on the mooring wire (F1) in order

to apply a high and known load that simulates the

load on the line by means of hydraulic pressure. This

pressure is related to the torque applied by the jack on

the winch drum as shown in Fig. 11.

F1 = 60% MBL

Hydraulic

Jack

Bolted Bracket

Drum Flange

Payout Direction

Hydraulic gauge

Figure 11. Arrangement for testing the brake in one of the

mooring winches of LNG Tanker “Golar Winter”.

As we cannot apply a force equivalent to F1 that

represents 60% MBL of the line, we need to generate a

simulated torque (F2 x L2) equal to the actual torque

(F1 x L1) by applying a previously computed

hydraulic pressure with the jack. The formulae given

below simply compensate for the difference in radius

between drum and barrel (first layer) and the jack

attack point, referred to the drum centre.

Actual and simulated torque should be the same,

so Equation (1) is expressed as follows:

F1× L1= F2 × L2

(1)

All data are known except the F2 term, so their

value is shown in Equation (2).

32.20

= 74.40 ×1,000 = 28,184.47 kg

85.00

F1× L1 R+r

F2 = = BHC ×

L2 L2

(2)

Knowing the hydraulic jack effective piston area

(A), the normal pressure to the bracket contact area

applied by the piston of the jack with F2 force that

generates the simulated torque should be computed

in bars because the reading in this kit on the pressure

gauge (Fig. 15 right) is in those units.

28,184.47 kg kg bar

= = 560.66 × 0.980665 = 549.82bars

50.27cm cm

(3)

5.2 Procedure for setting up and testing the BHC of the

winch

Once the pressure to be applied by the hydraulic jack

was computed to simulate a torque equal to the actual

torque that, with the wire rope on the first layer of the

drum, is generated by a force equal to F1 (60% MBL),

the following steps should be carried out:

1 The hydraulic jack should be checked to ensure

that there is proper hydraulic oil level and that the

pressure gauge is calibrated and certified.

2 The drum flange and/or the split disk (the notched

flange that divides the storage from the tension

sections of a split drum) must be equipped with a

hole to install the bracket. In this test, it was used

the hole on the split disk (Fig. 13).

3 There should be enough free space on the split

disk to accept the testing gear. To this end, some of

the wire was spooled off (Fig. 12 right).

4 The winch drum should be turned to set the hole

at 90 degrees to the deck or bedplate in order to

position the piston jack subsequently underneath

with their supporting surface in horizontal

position (Fig. 13 left and centre).

5 The spring is compressed (brake-on) at its

maximum value (BHC not less than 80% MBL) by

turning the brake handle clockwise accordingly.

The winch drive should be disengaged afterwards.

6 Pump up the jack until the computed pressure of

549.8 bars (550 is sufficient for practical purposes)

is shown on the pressure gauge assuring that this

reading has been stabilised (Fig. 13 right).

7 To find the correct set-up of the winch band brake,

we reduce the spring residual compression by

turning the brake handle smoothly anticlockwise

while watching the pressure gauge reading (Fig.

14 left).

8 When it comes to a slight reduction in pressure

gauge reading, the simulated torque which

represents a force F1 equal to 60% MBL with the

wire on the first layer of the drum is achieved (Fig.

14 right).

9 The indicator ring on the spindle should be

adjusted by using an Allen key so that it coincides

with the permanent index mark made on the fixed

plate for adjustment (Fig. 15).

10 The test is completed.

Regarding the winch drum and its band brake, it is

important to notice that it does not matter if the equal

torque is generated either by the hydraulic jack or by

the pull on the wire line; the reaction will be the same.

Therefore, when the jack computed hydraulic

pressure is applied, we equate torques, not forces

because of unequal lever arms. For this reason, it is

not necessary to carry out the test with one layer of

wire rope on the tension section of the split drum (the

actual condition where the force F1 generates the

torque); in fact, in this test the wire rope was spooled

on the storage section, therefore with several layers

(Fig. 13).

718

Figure 12. Mooring winch of split drum type dotted with

spring-applied band brake with manual release where the

brake test was performed. The necessary wire rope was

spooled off to have enough free space.

Figure 13. The bracket installed on the split disk (left); the

hydraulic jack positioned underneath ready to apply

hydraulic pressure (centre) and the operator pumping up

pressure with the lever until the pressure gauge reading

reaches 549.8 bars (right).

Figure 14. Winch operator turning the brake handle

anticlockwise to apply the residual compression on the

spring (left) until a slight reduction in the pressure gauge

reading is seen (right).

Figure 15. Nut-spindle-rod-cylinder with spring where the

indicator ring and the fixed plate for adjustment are shown

(left), and indicator ring position adjusted after the test to

the permanent mark on the fixed plate (right).

6 CONCLUSIONS

Mooring manoeuvres entail an inherent risk that

demands the utmost attention on-board to minimise

it. Accident reports showing the fact that improper

set-up of winch band brakes had been found to

contribute to several casualties confirm the need to

maximise the performance of this task in mooring

operations. On large ships, there is an unstoppable

tendency towards using dedicated self-stowing

mooring winches of the split drum type fitted out

with band brakes instead of warping drums. The

brakes of those winches have the safety function of

rendering before potential breaking of the lines and

their subsequent snap-back, releasing the tension in a

controlled manner once it increases to a pre-set

maximum force. To this end, the BHC of winches

should be set to hold 60% MBL of the line on the first

layer.

The three types of winch band brake application

were analysed, of which the manually applied is not

reliable enough from the safety point of view. The

current trend is to use band brakes of the spring-

applied type either with manual setting and release or

with hydraulic release, because they overcome most

drawbacks the manually applied application has.

Nevertheless, the hydraulic release seems the best

option. This is because, once preset, the spring

automatically applies the correct force and the

operator does not need to re-apply the torque by the

brake handle aside from the fact that, due to wear and

tear of the linings, visual check reveals that the

indicator ring does not coincide with the fixed mark

on the plate for adjustment. Actually, the spring acts

as a dynamometer that shows the constant force

applied when the indicator ring position is in line

with the fixed plate for adjustment after being preset

through a winch brake test.

The theory behind and the procedure to carry out

a winch brake test to set the BHC of winches has been

explained through an actual case. On-board different

winches designs can exist, so it is recommendable to

make an Excel spreadsheet to compute the pressure

the hydraulic jack (taking into account their

particulars) needs to apply on each of them.

REFERENCES

[1] ATSB (2006). Australian Transport Safety Bureau Marine

Occurrence Investigation nº 232: “Creciente” Mooring

accident report.

https://www.atsb.gov.au/media/24295/mair232_001.pdf

[2] Clark, I. C. (2009). Mooring and Anchoring Vol 1.

Principles and Practice. The Nautical Institute

[3] DMAIB (2014a) Danish Maritime Accident Investigation

Board: “Pachuca” Mooring accident report.

https://dmaib.com/reports/?query=Pachuca

[4] DMAIB (2014b). Danish Maritime Accident Investigation

Board: “Torm Republican” Mooring accident report.

https://dmaib.com/reports/?query= Torm+Republican

[5] ISGOTT (2006). International Safety Guide for Oil

Tankers and Terminals (5th edn). Witherby & Co Ltd.

[6] ISO (2012). ISO 3730:2012 Shipbuilding and marine

structures - Mooring winches.

[7] ISO (2017). ISO 7825:2017 Shipbuilding - Deck machinery

- General requirements.

[8] MAIB (2001). Marine Accident Investigation Branch

report 1/2001: “Alfa Britannia” Mooring accident report.

https://assets.publishing.service.gov.uk/media/547c7162

e5274a428d00010d/alfa-britannia.pdf

[9] NTSB (2014). National Transportation Safety Board

Accident NTSB/MAB-14/21: “Harbour Feature” Mooring

accident report. https://www.ntsb.gov/investigations/

AccidentReports/Reports/MAB1421.pdf

719

[10] OCIMF (2018). Mooring Equipment Guidelines (MEG4)

(4th edn). Witherby Publishing Group Ltd.

[11] OCIMF (2019). Effective Mooring (4th edn). Witherby

Publishing Group Ltd.

[12] Schnorr Corp. (2003). Handbook for Disc Springs.

https://schnorr.com/wp-

content/uploads/2018/05/Schnorr-Engineering-Design-

Handbook.pdf

[13] Søren Bøge, P. (2013). Mooring-Do it Safely. A guide to

prevent accidents while mooring (Danish Maritime

Authority). Seahealth Denmark.

[14] Steamship Mutual (2015). Risk Alert: Mooring winch

brake holding capacity. Steamship Mutual, London.

https://www.steamshipmutual.com

[15] UK P&I (2016). Risk Focus: Consolidated 2016.

Moorings, pp. 17-26 and APPENDIX “Understanding

mooring incidents”, pp. 27-34.

https://www.ukpandi.com

[16] Vervloesem, W. (2009). Mooring and Anchoring Vol. 2.

Inspection and Maintenance. The Nautical Institute.