201746 Automatic shutdown of main engine
An outbound tanker was transiting a restricted area at the port entrance. Suddenly, the main engine shut down. The Master quickly ordered the forward manoeuvring station to let go the starboard anchor. Meanwhile, the pilot ordered the escort tug to assist the ship while the Master ordered the port anchor dropped in sequence.
In spite of the actions of the crew and pilot, the vessel made contact with several channel markers before the main engine could be restarted and the tug made fast.
An investigation of the incident revealed that the oil mist detector had shut down the main engine due to a false detection of oil mist in the crankcase. The system was configured to allow only one second between the detection of oil mist (or other anomaly) and a shutdown. No human intervention was possible.
Lessons learned
● While automation is desirable for safety, so too is the possibility of human intervention if needed.
● Current class rules allow automation systems to be manually overridden (except in cases where manual intervention will result in a total failure of the main engine, for example in case of over speed), given a manned engine room and alarms advising of the override.
● Certain models of oil mist detectors can be programmed with varying delays for shutdown such that when navigating in restricted waters the delay before shutdown is longer than when in open sea, thus giving time for emergency action.