Confined Spaces


Confined spaces can create unsafe atmospheres and can cause serious injury or death.  The four potential main atmospheric hazards encountered on fishing vessels are:

  1. Oxygen deficiency i.e. the lack or reasonably foreseeable lack of oxygen which can occur due to biological or chemical reactions such as when fish rot or metals rust or corrode or another gas displaces the oxygen.
  2. Oxygen enrichment i.e. too much oxygen, for example during hot work, oxygen tanks and lines supplying the torch may leak oxygen into the air.
  3. Explosive/flammable atmosphere e.g. the presence of methane, propane or other flammable/explosive gases in the air.
  4. Toxic atmosphere e.g. the presence or build up of a harmful gas, fume or vapour such as carbon monoxide, hydrogen sulphide, methane, carbon dioxide or escaped refrigerant gas.

Rotting fish can produce gases such as hydrogen sulphide, hydrogen cyanide and carbon dioxide. Petrol or diesel generator used in a confined space can cause carbon monoxide poisoning.

Most atmospheric hazards will occur in confined spaces or other watertight compartments which have little or no ventilation. As a result it may be unsafe to enter an enclosed compartment or confined space.

Examples of Potential Confined Spaces

Example of potential confined spaces on fishing vessels include:

  • Tanks such as refrigerated salt water (RSW) tanks, fuel tanks, fresh water tanks and sea or fresh water ballast tanks
  • Fish holds containing decaying fish, fish waste or offal
  • Void spaces
  • Stores containing chemicals

All enclosed spaces must be treated with caution before opening or entering. In order to enter such areas, safe systems of work must be in place which may include atmospheric testing, use of appropriate breathing apparatus, safety harnesses and safety lines, appropriate training, emergency response procedures and rescue arrangements.

Never go into an enclosed space to assist someone in trouble without wearing the appropriate safety equipment and having back up from other crew members.

For further information see the safety alert in relation to  refrigerated seawater systems on fishing vessels and the Confined Spaces Section of our website.