Immersion Suits and Thermal Protection
One immersion suit for every person on board on cargo ships; three per lifeboat plus thermal protection for the rest on passenger ships. It is the count, not the suit, that changes with the ship.
Operational Explanation
Immersion suits and thermal protective aids protect against hypothermia for people in the water or on a survival craft awaiting rescue. The LSA Code sets precise technical requirements: the suit must be able to be “unpacked and donned without assistance within 2 min, taking into account any associated clothing, and a lifejacket if the immersion suit is to be worn in conjunction with a lifejacket” (LSA Code, 2.3.1.1). Two points about that wording, both sources of error: the two minutes cover unpacking as well as donning, not donning alone; and the Code says “within” — exactly two minutes complies. The common phrase «in less than two minutes» is stricter than the Code. Note too that “after demonstration” does not belong to this provision but to the lifejacket one (2.2.1.4), where the time is one minute; it must cover the entire body except the face, with hands covered unless integral gloves are fitted; it must not continue to burn or melt after being enveloped in fire for 2 seconds; and it must guarantee no undue entry of water after a jump from at least 4.5 metres.
Passenger ships must have, for every lifeboat, at least 3 compliant immersion suits, plus a thermal protective aid for every person not provided with an immersion suit; these requirements do not apply to persons on totally or partially enclosed lifeboats, or on ships operating exclusively on routes in warm climates where the Administration considers them superfluous.
Regulatory Reference
SOLAS III/32.3 (cargo ships): “An immersion suit of an appropriate size, complying with the requirements of section 2.3 of the Code shall be provided for every person on board the ship” — one suit per person on board (III/32.3.2), plus additional suits for watch and work stations located remotely from where suits are normally stowed (III/32.3.3). The same III/32.3.2 allows an exemption for ships constantly engaged on voyages in warm climates, as determined by the Administration, but expressly limits it to “ships other than bulk carriers, as defined in regulation IX/1”: no bulk carrier can be exempted.
SOLAS III/22.4 (passenger ships): at least three immersion suits for every lifeboat, plus a thermal protective aid for every person on board not provided with a suit, with exemptions for totally enclosed lifeboats and for warm-climate voyages.
LSA Code Sections 2.3 (immersion suits) and 2.5 (thermal protective aids): technical requirements on donning time (within 2 minutes), fire resistance, body coverage and watertight integrity.
Scope of Application
Every ship subject to SOLAS Chapter III. The counting criterion, however, differs between the two categories, and the rule that applies to most of the fleet is the cargo ship one.
| Cargo ships — III/32.3 | Passenger ships — III/22.4 | |
|---|---|---|
| Criterion | Per person on board | Per lifeboat |
| Immersion suits | One for every person on board | At least three for every lifeboat |
| Additional suits | Yes, for watch and work stations remote from the usual stowage | — |
| Thermal protective aids | — | One for every person not provided with a suit |
| Exemptions | Warm climates, as determined by the Administration — every bulk carrier excluded (III/32.3.2, as defined in regulation IX/1) | Totally enclosed lifeboats; warm climates |
On suits per person it is the cargo ship regime that is the stricter one: on a cargo ship every person must have their own suit, whereas on a passenger ship the count starts from the lifeboats and everyone else is covered by thermal protective aids. Anyone looking for the “three per lifeboat” criterion on a cargo ship is reading the wrong rule.
Procedure / How to Complete It
- First establish which rule applies to the ship: III/32.3 for a cargo ship, III/22.4 for a passenger ship. Everything that follows depends on that choice.
- On a cargo ship: verify one suit for every person actually on board, including the additional suits for watch and work stations remote from the usual stowage; on a passenger ship: verify the three suits per lifeboat and the thermal protective aids for persons not provided with a suit.
- Periodically inspect the condition of the suits (material integrity, zips, watertight seal) per the LSA maintenance programme.
- Include timed practical donning of the immersion suit in periodic drills, verifying compliance with the 2-minute limit.
- Verify correct storage of the suits in a readily accessible location near the embarkation stations.
- Train the crew on the operational difference between immersion suits and thermal protective aids, and when each is actually required based on lifeboat type.
Practical Example
Example: during the monthly abandon ship drill, three crew members on a rotating basis time their donning of the immersion suit, verifying that the complete donning time, including lifejacket, stays within the 2 minutes required by the LSA Code.
What Typically Goes Wrong
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| Immersion suits counted from the number of lifeboats on a cargo ship, where the criterion is per person | Fewer suits than persons embarked, with the shortfall never showing up in any count | Start from the rule that applies to the ship (III/32.3 or III/22.4) and only then count: on cargo ships the reference is the number of persons on board, not the number of lifeboats |
| Immersion suit donning rarely practised or never timed during drills | Crew unaware of real donning times under emergency conditions | Include timed practical donning in periodic drills, not just simulation of the route |
| Suits stored in locations not immediately accessible from the embarkation stations | Delay in retrieving equipment during a real emergency | Verify that suits are stored in a readily accessible location, consistent with their emergency function |
What the PSCO Checks
Operational Tips
- Always time donning during drills: the 2-minute limit is a real technical requirement, not a generic guideline.
- Verify the required equipment quantity whenever the crew or passenger configuration on board changes.
- On a cargo ship the number of suits follows the number of persons embarked: when the complement changes, the requirement changes. Watch stations remote from the usual stowage need their own suits, not double-counted ones.
- Don't confuse immersion suits and thermal protective aids: they have distinct technical requirements and use cases under the LSA Code.
Preparation checklist
Educational checklist. This summary supports learning and preparation only. It does not replace the vessel’s approved procedures, manuals, statutory documents, company SMS, or applicable official requirements. Completing it demonstrates neither compliance nor readiness for an inspection: it shows that a list has been read, not that the ship is in order. Always verify the current documents carried on board.
- Applicable rule identified: III/32.3 (cargo ship) or III/22.4 (passenger ship)
- On a cargo ship: one immersion suit for every person on board, plus the suits for watch and work stations remote from the usual stowage
- If the ship is a bulk carrier (regulation IX/1): the warm-climate exemption is not available, the suits must be carried in any case
- On a passenger ship: at least three immersion suits per lifeboat and a thermal protective aid for every person not provided with a suit
- Maintenance condition of the suits periodically inspected
- Timed practical donning included in periodic drills
- Suits stored in a location readily accessible from the embarkation stations
- Crew trained on the operational difference between immersion suits and thermal protective aids
FAQ
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Last substantive revision of this page: 13 August 2026 · page fingerprint 1af0f563cab0