Vessel : DSV Peerless Stena-I, offshore diving support vessel, GRT-3000
Location : Bombay high

Vessel was being maneuvered at night, operation by Master from bridge, to bring the vessel closer to a platform, so that diving operations can be started by day break. Vessel had port and stbd main engines to which fwd out put shaft is connected through clutch and speed up gear box to shaft alternators, and Aft out put shaft is connected to main CPP type propeller thro’ clutch and reduction gear box. The high voltage shaft alternator is used for 2 bow thruster on fwd and 2 stern thrusters at the aft. The ship can be dynamically positioned (DP-Ship) close to platform (for diving operations) when all thrusters and propeller are running and bridge controls, all thro’ a DP computer.

On the fateful day, at night Master had to change over to hand control from auto mode, due to weather was bad and sea was rough. The hand lever control operations were so rough, the duty engineer had to call and tell him twice to give smoother movements, inspect of this rough handling from Bridge continued. At 0600 hrs, next morning, there was a very loud noise and explosion in engine room. Duty engineer informed bridge (it was so loud, whole ship heard this) informed (CE) also, in ECR it was noticed that stbd ME. No.1 bow thrusters and no.1 stern thruster was still running, and instructed captain to take ship away from oil field to safe area.

On investigation it was found due to rough maneuvering port ME governor out put lever link to fuel control reach, had come off, and engine went out of control into overspeed. Over speed trip mechanism did not work, as a result the speed up gear box (on fwd out put side) exploded destroying the G/Box and the shaft alternator completely. Also this explosion damaged few pipe lines and other small fragile equipments in the vicinity. As a result the vessel was out of action for four months till new gear, shaft alternator, clutch etc. were procured and installed. There was no causality luckily, as duty engineer and his assistant were in ECR.

Lesson learnt :

1)Governor link tightness to be checked periodically

2)Also over speed trip mechanism to be tested at regular intervals