Two aframax tankers had just completed an offshore shipto- ship (STS) transfer of diesel oil. As the last lines were slipped, the quarters of the two vessels began to close. In order to check this movement, the STS superintendent on board the designated manoeuvring vessel (on the right hand side) ordered dead slow ahead and 10° port rudder. However, the vessel's diesel engine failed to start.

This information was relayed to the superintendent after a slight delay, by which time he had ordered slow ahead and a larger port rudder angle. He immediately broadcast a hurried and incomplete VHF safety warning but did not sound an alarm on the whistle, so the other tanker was not aware of the emergency.

As the manoeuvring vessel's bow began to swing very slowly to port towards the other vessel, the superintendent ordered slow astern. This time, the engine started and the superintendent immediately ordered full astern followed by a series of engine and helm orders given in rapid succession. Seconds later, the manoeuvring vessel's port anchor struck the starboard lifeboat on the other vessel. It was later established that the engine failed to start due to a dirty air start pilot valve that blocked the starting air to the cylinders.

Lessons learnt

1. When manoeuvring in close proximity to another vessel or navigational hazard the possibility of something going wrong must be carefully considered. In such situations, bridge and engine room teams need to be trained and ready to respond quickly and effectively to engine and steering failures.

2. Good internal and external communications are vital when operating close to another vessel. Dedicated communications operators, the correct use of radio procedures and a common language are all essential to ensure this is achieved.

3. This was the superintendent's eighth consecutive STS operation, and it is possible that the cumulative effect of long working hours over a three week period adversely affected his alertness. Proper monitoring of rest hours helps to prevent the onset of fatigue, but Masters should also keep an eye out for the signs of fatigue among their crew and any person key to ship safety, such as STS superintendents and harbour pilots.

Source: Mars/Nautical Institute