Confined Space Entry: Vital 2026 Safety Checklist for Crews
A worker on an offshore drilling unit climbed down into a leg to check a pump. When he did not come back, a colleague went after him, then another. By the time someone arrived wearing breathing apparatus, three people were dead. This is the hard truth of confined space entry at sea: the air can kill in minutes, and it often kills the rescuers too.
This guide covers the hazards, the rules, a practical checklist and the safeguards every seafarer should insist on before going into a tank, hold or void.
Why Confined Space Entry Is So Dangerous
An enclosed or confined space is any area with limited openings, poor natural ventilation and no design for continuous work. On ships that includes cargo holds and their access trunks, ballast and double bottom tanks, cargo and fuel tanks, cofferdams, void spaces, chain lockers, boilers, engine crankcases, sewage tanks and inert gas spaces.
The danger is that you cannot see, smell or feel most bad air. A space that looked safe yesterday can be deadly today. That is why enclosed spaces remain among the most lethal workplaces in the whole maritime industry.
The main hazards
- Oxygen depletion: rusting steel, organic cargoes (grain, soya, timber, coal) and inert gas all use up or push out oxygen.
- Toxic gases: hydrogen sulphide from rotting residues or sewage, carbon monoxide, benzene and other cargo vapours.
- Carbon dioxide: produced by fermenting organic cargoes and heavier than air, so it collects low down.
- Flammable atmospheres: hydrocarbon vapours from fuel or cargo residues.
- Physical risks: falls through hatches, slippery ladders, heat, poor lighting and tight access holes.
Real cases show how quickly confined space entry can go wrong. In June 2022, three stevedores died in a cargo hold access space on the bulk carrier Berge Mawson in Indonesia, where the oxygen level was later measured at below 1%. Industry studies have repeatedly found that a large share of confined space deaths are would-be rescuers who rushed in without protection.
Rules and Regulations for Confined Space Entry
Several layers of rules govern confined space entry on board:
- SOLAS Regulation III/19 (IMO Resolution MSC.350(92)): since January 2015, crew with entry or rescue duties must take part in enclosed space entry and rescue drills at least every two months.
- SOLAS Regulation XI-1/7 (IRClass summary): since July 2016, ships must carry at least one portable atmosphere testing instrument able to measure oxygen, flammable gases, hydrogen sulphide and carbon monoxide.
- IMO Resolution MSC.581(110): the revised recommendations for entering enclosed spaces, adopted on 27 June 2025, replacing the 2011 Resolution A.1050(27).
- The ISM Code: your company Safety Management System (SMS) must include entry procedures, permits, risk assessments and emergency plans.
What changed with the new IMO recommendations
According to DNV and class guidance, the revised recommendations ask every ship to keep an enclosed space register listing each space, its connected and adjacent spaces, and their hazards. Connected spaces must be treated as dangerous until tests prove otherwise. Carbon dioxide testing is now clearly included, and single-person entry is not permitted.
The recommendations give clear safe-entry readings: 20.9% oxygen by volume, carbon dioxide below 0.5%, flammable gas below 1% of the lower flammable limit, and toxic gases below 50% of their occupational exposure limit. An entry permit should be valid for no more than eight hours.
Confined Space Entry Checklist for Seafarers
Use this confined space entry checklist alongside your company permit. If any answer is “no”, stop.
Before entry
- Is the space listed in the register and has a risk assessment been done?
- Has the Master or responsible officer signed the entry permit?
- Is the space isolated from pipes, power, cargo and inert gas?
- Has it been ventilated, and will ventilation continue during the work?
- Has the atmosphere been tested at top, middle and bottom, and are readings recorded?
During entry
- Does every entrant carry a personal gas monitor and a radio?
- Is an attendant posted at the entrance who will never go in alone?
- Are breathing apparatus, a rescue harness, tripod or hoist and a stretcher ready at the entrance?
- Are communication checks agreed, with a clear signal to get out?
After entry
- Are all people and tools accounted for?
- Is the space closed and secured so no one enters by mistake?
- Has the permit been closed and any lessons shared at the next safety meeting?
Key Precautions and Safeguards
Never rescue alone
If someone collapses during a confined space entry, raise the alarm, keep talking to them and wait for the rescue team with breathing apparatus. As Gard advises, follow the plan you have practised. A second casualty helps no one.
Trust the meter, not your senses
Before any confined space entry, check that gas meters are calibrated and bump-tested. Test before entry and keep monitoring, because conditions change as cargo residues are disturbed or the space warms up.
Watch for hidden routes
Bad air can flow in from a connected space, an open valve or a leaking bulkhead. Hold access trunks and forecastle stores next to cargo holds are common killers.
Look after the people
Tired crew make mistakes. Plan entries in normal working hours where possible, and respect rest limits, as explained in our guide to hours of rest violations. Shore workers such as stevedores and repair teams must also be told about the hazards and follow the same permit.
Your right to say stop
Every seafarer has the right to stop work they believe is unsafe. Speaking up about a missing test or an absent attendant is not disobedience; it is good seamanship. For recent cases, see our report on enclosed space incidents on ships.
FAQ
What oxygen level is safe for confined space entry?
IMO guidance sets 20.9% oxygen by volume, with carbon dioxide below 0.5%, flammable gas below 1% LFL and toxic gases below 50% of the exposure limit. If readings are outside these limits, keep ventilating and test again.
How often must enclosed space rescue drills be held?
Under SOLAS, enclosed space entry and rescue drills must be carried out at least once every two months.
Can one person enter a confined space alone?
No. Single-person entry is not permitted. An attendant must stay at the entrance, and a rescue team must be ready.
Conclusion
Confined space entry will always be part of life at sea, but deaths in tanks and holds are preventable. Know the hazards, follow the permit, test the air, never enter or rescue alone, and drill until the response becomes automatic. When in doubt, stay out.
Disclaimer: This article offers general guidance only. Always follow your company’s Safety Management System, permit-to-work procedures, the Master’s orders and flag State rules.
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