Our loaded VLCC was preparing to carry out an STS operation offshore. The ‘daughter’ or receiving vessel into which cargo was to be lightered was also a VLCC and was at anchor.
Our vessel stopped parallel to the receiving tanker and approximately 150 metres off it, and then two large tugs began pushing our VLCC bodily towards the lightering vessel. When the two vessels were about 10 metres apart, a strong gust of wind caused the lightering vessel’s bow to yaw to starboard in her anchored position and the two vessels’ bows made contact.
Apart from inflicting some damage to the internals in way of the side ballast tanks, the impact ruptured the forward pneumatic fender. As the deflated fender was crushed between the two hulls, its external chains and metal fittings created deep gouges and scratches on the shell plating of both vessels.
While a tug was deployed to control the yaw of the lightering vessel, lines were quickly passed between the vessels and the mooring operation was completed without further incident.
Result of investigation
1 The mooring operation had been properly planned and an experienced mooring contractor specializing in STS operations had been appointed by the charterers;
2 Sufficient number of fenders were deployed on the lightering vessel by the mooring company;
3 STS checklists were completed correctly and the mooring plan was agreed with the Mooring Master;
4 The mooring operation was planned for daylight hours only;
5 The weather and sea conditions at the time of approach were favourable for the planned operation, however, when the vessels were about 10 metres apart a gust estimated to be about 25 knots suddenly blew across the heading of the two vessels;
6 Drug and alcohol tests were conducted onboard and all were negative.
Root cause/contributory factors
1 Too much reliance being placed on the Mooring Master’s knowledge and experience;
2 Own ship’s bridge team failed to observe the approach of strong gust, being fully engrossed only in the mooring operation.
Fleet instructions issued reminding Masters and bridge teams to:
1 Be aware that the master is overall in charge of STS operations and the Mooring Master operates only in an advisory capacity;
2 Promptly raise any concerns with regard to the manoeuvre(s) being planned or executed, with the master exercising his authority to override actions of the Pilot / Mooring Master to ensure safety of life, property and environment;
3 Be aware of the prevailing and developing environmental and traffic conditions, and abort the manoeuvre or operation in progress if the safety of the vessel should be compromised;
4 Record all events and information in the bridge log book correctly.
Source: Mars/Nautical Institute