A ro-ro passenger vessel with a skeleton crew of four (Master, chief engineer, bosun and engine rating) was being manoeuvred out of dry dock, dead-ship but with two tugs. Further work was to be done alongside in order to bring the vessel up to operational status. The berth to which the vessel was assigned was shorter than the vessel itself, so that nearly half of the vessel was not lying flat on any sort of fender.

Extra manpower was provided by seven dry dock employees at the Mooring stations. The tug boats were made fast fore and aft. One crew member and four shipyard personnel were assigned to the forward mooring station, while at the aft mooring station there were two crew and three shipyard personnel. Apparently, the stern line was passed around a lower pedestal fairlead and in between the two aftermost button-rollers and sent ashore.

A second line at the aft mooring station was sent ashore as a spring and was fed around a higher pedestal fairlead and between the two forwardmost button-rollers. This resulted in the aft spring line being higher than the stern line yet crossing from below this line, causing an upward thrust on the lower pedestal fairlead.

At some point in the manoeuvre the aft spring line came under extreme tension. The stern line absorbed some of the tension, which was transferred to the lower pedestal fairlead. Unexpectedly, the roller fairlead was launched from its pedestal, fatally injuring one of the shipyard personnel.

Some of the findings of the official report were:

• The immediate cause of the accident was the failure of the two 10mm bolts holding the roller-keep in place, which sheared off under the tension generated by the mooring ropes.
• The berth configuration, which supported only half of the vessel, and the position of the fender contributed to a turning moment that could easily cause uneven tension on the fore and aft mooring ropes.
• The handling of mooring ropes was not discussed, nor were the dangers associated with mooring stations. None of the seven shipyard personnel present at the mooring stations on board the vessel had any training in mooring operations.
• The crew members at the aft mooring station did not have the necessary experience and knowledge to handle mooring ropes safely.

Lessons learned

• Mooring a vessel involves great stresses. Always have experienced and sufficient crew to handle mooring lines. Never cross your mooring lines and never have them acting against each other in competing planes of action.
• Be aware of the forces acting on the mooring lines and stay clear of any areas of potential danger.

Reference: nautinst.org