Loss of Cooling Water

Report Text:

The ship’s main and auxiliary engines have a common cooling water system. This had been identified following a previous incident as a potential single-point failure and had been fitted with additional remotely operated isolation valves.  Use of these valves had been practiced through inclusion in the ship’s technical emergency reaction training programme.

The incident occurred soon after departure from port when a connecting rod failure in a generator led to a major loss of cooling water from the cooling system common to auxiliary and main engines, with resultant loss of propulsion.

The engineer officer on watch heard a series of loud noises from the auxiliary engine room. He went to investigate and identified the source as a generator which was on load supplying the main switchboard in parallel with another generator. He returned to the control room, started the stand-by generator, sounded the engineers’ alarm call and commenced taking the actions detailed in the technical emergency reaction checklist for isolation of the cooling water system.

The catastrophic failure of the connecting rod and consequent piston and liner damage had caused major loss of cooling water from the generator cooling system which is common to the main engine cooling system.  Loss of cooling water led to the shutdown of all main engines within three minutes of the failure, but the two generators supplying electrical power remained operational.

As had been practiced in previous reaction training, the engine room team used the remote isolation valves to prevent complete loss of water from the generator and main engine cooling water system.  Rapid refilling of the system header tank was then achieved by use of the remotely operated high capacity cooling water pump.

Main engines were restarted within two minutes of shut down.  Practiced and professional reaction by the engineers prevented escalation of the incident and ensured continued supply of electrical power and earliest possible restoration of propulsive power.

The incident demonstrated the value of making practicable system improvements where identified and in consolidating the benefit through effective reaction training drills.  This coupled with briefings gave staff complete confidence in system recovery.  Good situational awareness coupled with quick reaction led to isolation of the cooling water system on the damaged generator, which prevented complete loss of cooling water from the other generators and from the main engines.  Electrical power was maintained throughout the incident and, although main engines were lost for a couple of minutes, the bridge team were able to ensure safe navigation.

CHIRP Comment:

This report highlights the benefit of identifying specific risks, devising contingency measures and practicing them so that if a problem does arise, the situation can be quickly stabilised.