Bow thruster room flooded during fresh water transfer operation

What happened?

A vessel’s bow thruster room was flooded during fresh water transfer operations. The plan was to complete receiving fresh water in Tank No. 2 Centre first before moving to simultaneously fill Tank No. 1 Port & Tank No. 1 Starboard, while ensuring using soundings that neither tank was overfilled.

The Duty Motorman (about to end his shift) stopped receiving water into Tank No. 2 Centre believing that it had filled up, and transferred the supply to tanks No. 1 Port & Tank No. 1 Starboard as per the agreed plan.

The incoming Duty Engine Cadet sounded Tank No.2 Centre and realized that it was not yet full. This prompted him to stop and remove the transfer hose from Tank No.1 Port and returned the supply to Tank No.2 Centre. This tank had its sounding pipe linked to the bow thruster room.

Consequently, fresh water flooded the bow thruster room via the sounding pipe which was not locked, to the extent that the generator in the bow thruster room was submerged to about 2/3 of its height.

What went wrong?

• The sounding pipe of Tank No. 2 Centre was not closed (this was the sounding pipe linked to the bow thruster room);
• There was no adequate risk assessment of the fresh water transfer operation. There was no toolbox talk or discussion with the crew of the operation or the risks involved;
• The bilge emergency alarm was neglected by the Duty Engine Cadet;
• The emergency response plan was not followed during this incident.

What were the causes?

• Negligent watch-keeping practice;
• Poor supervision of task;
• Poor handover or shift change procedures;

Lessons learnt

• Requirement for 24/7 watch-keeping in the engine room;
• Better handling of shift change and handover processes;
• Better supervision required particularly of trainee (Cadet) personnel;

Deeper crew understanding of emergency response safety drills particularly for bow thruster flooding.

Members may wish to refer to the following incident:

• Water ingress to bow thruster space
  • July 2010 – very similar incident: Some “Key Issues” highlighted at that time:
    • Failure of basic watch-keeping practices;
    • Lack of understanding of Chief Engineer’s Standing Orders