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英国海上事故调查局（MAIB）安全公告

同时解开两条缆绳致缆绳不受控

事故描述

一艘近海支持船右舷系泊在岸。船尾的系泊装置包括内侧的两条倒缆，以及外侧的两条艉缆，均系在缆桩上（如图示）。船舶解缆人员和驾驶员进行了工作前的安全会议，为离港做准备。

离港时，潮流以约1.5节的速度流向船尾。离港操作计划是运转内侧（右舷）方位推进器来抵消潮流，用外侧（左舷）方位推进器来保持船舶不漂离岸边。船长、大副和港口的引航员当时在驾驶台。船长和引航员商量过离港计划，但仅限于操舵，未提及解缆。驾驶台和解缆人员之前通过手持超高频无线电话交流。引航员与岸边解缆工用甚高频无线电话进行交谈。

船尾解缆人员由两名一水组成，每人站在一组缆桩旁边。岸上解缆工把倒缆从码头缆桩上解开。右舷一水将尾倒缆收回甲板，系于缆桩。然后，左舷一水同时松开了两条尾缆。紧接着，岸上解缆工将首缆和尾缆都从岸上解开，并将缆绳尾端扔进水中。可是，两条缆绳对于一水来说太沉，难以同时收回。当他尽力收回其中一条缆绳时，另一条被吸进了一个方位推进器吸入口里。更糟糕的是，被他收回的那条缆绳很快与绞进推进器的缆绳纠缠在一起。

图示：系泊装置

他立刻向驾驶台警示并告知其困境，同时要求两台推进器停车。然而，船长意识到停止推进器将无法再控制船舶。他也不知道哪个推进器吸入了缆绳，于是他将左舷推进器方位角调到零，并调整右舷推进器方位角，保持船舶不漂离岸边，同时抵消潮流。

同时，内侧的水手跑到左舷来帮忙。即使如此，两个水手也不能控制住两条尾缆，尾缆从他们手里挣脱。这时，其中一个水手无意中踩进一条缆绳里，脚立即被缆绳收紧，人随着往舷外跑的缆绳朝导缆孔倾倒。另一个水手见状抓住了他，在缆绳在导缆孔里下滑速度变快之前，成功地将他的脚挣脱出来。幸运的是，该水手仅脚部淤青，该船也被重新系泊在岸，没有进一步事故。

事故教训

1.当多条缆绳系泊时，同时解开多条缆绳就是自找麻烦。除非另有合理的考虑，最好的做法是解开缆绳时最好先解一条。另一个实用技巧是在进港时就考虑到解缆的实用性，并在离港声明和工作前安全会议中讨论解缆预期程序和方法。

2.并非所有人都会读心术，能预测到别人意图。不要假定别人将按你心意行事，也不要在想解开一条缆绳时松开两条。

3.在紧急情况下，快速思考是关键，但花一点时间衡量可选行动方法的利弊同样重要。在这个案例中，如果停止推进器而不采取其他措施会使得船舶不受控，然而留给船长意识到这一点的时间仅有短短几秒钟。

MABI报告原文 

Narrative

An offshore support vessel was moored starboard side to. The mooring arrangements on the stern comprised two spring lines made fast on bitts on the inboard side and two stern lines made fast on bitts on the outboard side (see figure). In preparation for the departure, the vessel’s mooring and bridge teams conducted a tool-box talk.

At the time of departure, the tidal stream was setting onto the vessel’s stern at a rate of about 1.5kts. For letting go, the inboard (starboard) azimuth thruster was set to counteract the tidal stream and the outboard (port) azimuth thruster was set to keep the vessel alongside. The master, chief officer and a harbour pilot were on the bridge. The master and pilot had discussed the manoeuvring aspects of the departure plan, but not the method or expectations for unmooring. Communication between the bridge and the mooring teams was via hand-held UHF radio. The pilot was talking with the shore linesmen via VHF radio.

The aft mooring team comprised two ABs, one by each set of bitts. The shore linesmen first cast off the spring lines from the quayside bollards. The aft spring lines were recovered on deck by the AB at the starboard bitts. The AB on the port side then slackened both of the stern lines. The shore linesmen then let go the head and stern lines from the quayside and dropped their ends into the water. The lines were too heavy for the AB to recover simultaneously and, as he heaved in one of the stern lines as fast as he could, the other line was ***ed into one of the azimuth thruster suction inlets. To make matters worse, the line being tended by the AB soon twisted around the line that was fouling the thruster.

The AB handling the stern line quickly alerted the bridge to his predicament and asked for both thrusters to be stopped. However, the master realised that this would leave the vessel without any means of control. The master did not know which of the thrusters was fouled so he set the pitch of the port azimuth to zero and adjusted the starboard azimuth to keep the vessel alongside, as well as counteracting the tidal stream.

Meanwhile, the AB from the inboard bitts moved to the port side to assist. Even so,

the two ABs were unable to hold on to the stern lines, which were pulled out of their hands. At the same time, one of the ABs inadvertently stepped into a bite in one of the lines that quickly tightened around his foot and then carried him toward a fairlead as the line ran overboard. The second AB saw what was happening so grabbed the other AB and managed to push his boot off just before it became fast in the fairlead. Fortunately, injury was limited to a bruised foot, and the vessel was re-secured alongside without further incident.

The Lessons

1. Letting go all lines when doubled up is asking for trouble. It is best practice to

single-up before casting off unless there are sound reasons to do otherwise. It is also useful to take into account the practicalities of letting go when securing lines on arrival and to include the intended procedure and method for letting go during departure briefs and tool-box talks.

2. People are not mind-readers and cannot predict the actions of others. Do not assume that others will do as expected and don’t slacken two lines if only one is intended to be let go.

3. In an emergency situation quick thinking is key, but taking a few moments to weigh up the pros and cons of alternative courses of action is just as vital. In this case, just a couple of seconds of thinking time was all that was required for the master to realise that stopping the thrusters would have led to his vessel being set upriver without any means of control.