May 2007: Alarms for abnormal rises in water levels in compartments

This safety update is issued to raise awareness of the potential serious risk to safety on board a vessel due to abnormal rises in water levels in compartments. It provides safe practice tips for how best to reduce the risks and to alert people to the risk to safety associated with the flooding of compartments where buoyancy or stability may be compromised.

This safety update is for

  • New Zealand ship owners, masters and crew
  • Surveyors
  • Classification societies in New Zealand and class surveyors
  • MNZ maritime officers, investigators and technical advisors
  • Shipyards and boat builders



In October 2015 a fishing vessel and her crew of three was lost. The likely cause of the sinking was flooding of the fish room.


Precautions and procedures

As a matter of good practice, ship owners, masters, crew and surveyors should be aware of the potential risks associated with flooding of compartments where buoyancy or stability may be compromised. Steps should be taken to alert crew of any abnormal rises in water levels in compartments.

Fish rooms are particularly prone to flooding as fish scales may block pumps and valves and other debris may prevent water discharge. New Zealand fishing boats commonly seem to have large fish rooms that if flooded will cause stability issues. On such vessels, more than one means of pumping should be in place along with hatch openings in appropriate locations designed to prevent ingress.

Regular maintenance and monitoring of the pumps, valves and means of water discharge may reduce the risk of flooding. The maintenance of pumps should be included in the vessel’s safety system. Safe operating procedures for these tasks should be in place.

In addition to regular maintenance of the above, the use of an audible alarm that activates when water reaches a certain level can provide a further safeguard. The water-activated alarm should be installed so that it sounds when the water is at a level that where it is safe enough for crew to manually activate water removal without compromising stability. The level of the alarm should not trigger in normal safe operating conditions. Talk to your surveyor or naval architect for guidance on this.

Checking alarms should also be included in the vessel’s safety system and safe operating procedures so that the crew knows what to do if the alarm is activated.

It is noted that if an automatic submersible bilge pump is installed, a visual alarm is required on the helm as per Maritime Rules Part 40D.28C. It is recommended that this alarm be audible also.

Original source content - Safety Bulletin Issue 35, May 2017: Alarms for Abnormal Rises in Water Levels in Compartments.


Contact us for more help

If you have any questions about this safety update, please contact our Wellington office.


New Zealand (toll free):
0508 225 522

Tell us what you need help with and remember to include your contact details (email address and phone numbers).