The UK Club’s inspectors frequently find that ships’ mooring arrangements areboth ineffective and used inefficiently, such that mooring lines are subject tounnecessary chafing.

Mooring practices

Technical BulletinNUMBER 1 2002

UK P&I CLUB

In some cases, moorings have resembled ‘knitting’,suggesting that ships’ personnel have given very littlethought to the vessel’s mooring arrangement and howbest to utilise it. When moorings are being deployed,consideration should always be given to using the mostsuitable leads for ropes, taking into account shoresidefacilities.

The effectiveness of any mooring line or wire isinfluenced by two angles:

• The vertical angle the mooring line forms with thequay:

• The horizontal angle the mooring line makes with theparallel side of the ship.

The steeper the orientation of a mooring line, the lesseffective the line will be in resisting the horizontalloading put on it as the vessel moves in relation to thequay. Not all berths lend themselves to ideal leads,depending on ship type/size, and compromises have tobe made, but the officer in charge of mooringoperations should always be looking for the best leadsfor his lines – which aren’t necessarily the shortest.

A mooring arrangement should provide an efficientmooring pattern, facilitate safe line tendering and allowfor the safe and efficient handling of tug and fire wires.

Sharp objects can chafe mooring lines

A ship’s mooring system is designed to prevent the shipdrifting away from the berth and hold her in place inrelation to that berth. The effectiveness of the mooringsis dependent upon the configuration of the mooringlines. The security of a ship alongside is not somethingwhich happens of its own accord – it requires a goodunderstanding and use of the ship’s equipment.Considerable thought should be given to theconfiguration of the moorings, so that leads areeffective and do not create sharp angles. Considerationshould also be given to the order in which lines aredeployed, so as to maintain a safe working environmentat all times.

To prevent unnecessary dangers to ships’ personnel,and to prevent expensive mooring line damage,moorings should not be crossed over each other or beallowed to chafe against sharp objects.

Personnel on duty should ensure that moorings arechecked and tended at regular intervals and thatremedial action is taken to minimise or eliminatedamage to moorings. Actions should be taken toprevent chafing – ensuring that all rollers, deadmen,etc. are free to turn, wrapping canvas or old fire hosearound a mooring line at potential chafing areas and, inextreme cases, applying grease or other approvedlubricant to the line, again to reduce the effect ofchafing.

Mooring lines should be made up correctly once thevessel is in position. When using synthetic ropes onlarge sets of bitts, use two round turns(no more) on the first post, then figure-eight round both(fig.1, below). On smaller diameter bitts, the two roundturns should be around both posts (fig. 2).

Mooring lines should not be left on drum-ends – theseare designed for warping, not holding the weight of aship for long periods and there is a risk of lines slippingor being thrown off drum ends when used in thismanner. Excessive turns should not be left on theworking side of a split mooring winch – three turns(1 layer) are sufficient.

The strength of a line is dependent upon its condition –the condition of mooring lines in use should becontinually monitored, as lines are subject to wear andtear. Frayed ropes are weakened by a loss in ropediameter, damaged fibres / strands, etc. and can bedangerous to personnel working them. They should notbe used if at all possible, but replaced / repaired.

Fig.2 Small diameter bitts

Fig.1 Large diameter bitts

When a mooring line is under tension (under load), itstretches. Energy is stored in the line in proportion tothe load and stretch. If the line were to part, this built-up energy would suddenly be released. The ends of theline whip back striking anything in their path. This whipeffect is common to all lines. Even long wires underload can stretch sufficiently to part and whip back withconsiderable energy. Personnel should always avoid

Split winch used correctly

An example of a mooring line in poor condition

Mooring line left on drum end

UK P&I CLUBIS MANAGEDBY THOMASMILLER

For further information please contact:Loss Prevention Department, Thomas Miller P&I LtdTel: +44 20 7204 2307. Fax +44 20 7283 6517Email: lossprevention.ukclub@thomasmiller.com

standing in areas where a line is likely to whip backthrough should it part.

Ridings turns – rope buried under lower turns

Riding turns (where a rope is buried under lower turnson a winch) must be avoided. They make adjusting

moorings difficult as the rope under tension has to bepulled / prised out from the slacker, lower turns.If unnoticed, this can cause problems for mooringgangs as the line would initially pay out when slackingit back for letting go, but would then suddenly startheaving back in (the winch would still be turning as if toslack back the line). This could lead to a potentiallydangerous situation for anyone on the quay trying toremove the line from a bollard.

Unauthorised / untrained personnel must not bepermitted to wander around mooring stationsunsupervised. Failure to do so will significantlyincrease the potential for a serious - possibly fatal -accident.

The OCIMF publication Effective Mooring (1989Edition) is a valuable source of information with allmanner of advice on safe and efficient mooringpractices.