The causes of flooding vary. UK MAIB has identified that hull failures account for half of flooding incidents, with the remaining being sea water pipe failures (failed seacocks or associated pipework).

In order to minimise the possibility of equipment failure that may result in flooding, it is necessary to ensure that the watertight integrity of the hull is maintained by carrying out a regular and effective maintenance regime. This is especially required for older vessels as they may not have received the level of ongoing maintenance necessary to investigate and replace corroded pipework and fittings, or to ensure the integrity of the hull.

This maintenance regime should pay particular attention to those features of the vessel’s construction that are most likely to jeopardise the safety of the vessel and crew in the event of failure, including:

  • Watertight doors and hatches.
  • Hull and deck structures.
  • Freeing ports (should be clear of obstructions).
  • Bilge alarms – a working bilge alarm is a basic and extremely valuable device to detect and warn about unseen flooding in its critical early stages.
  • Seacocks and associated hoses and pipework should be of proper marine grade quality and all metalwork should be protected against electrolysis. Inspect and maintain all seacocks regularly. Regularly examine hoses and pipes associated with seacocks for:
  1. Chafing.
  2. Corrosion/electrolysis.
  3. Cracking and splitting, particularly around clamps. All hoses should be double clamped at terminations.
  4. Signs of vibration fracture/general deterioration.

If flooding is discovered, it is likely that the source is through a seacock, therefore, the first action should be to immediately close all seacocks. If possible, keep all seacocks closed when not in use. It is recommended that, if possible, secondary means of closing seacocks should be extended as high as possible under the deck to allow them to still be closed, even when deeply submerged in the flooded hull.