Enclosed space entry: what the Isle of Man Ship Registry’s latest guidance means for owners and operators

The Isle of Man Ship Registry (‘the Registry’) has published Technical Advisory Notice (TAN) 005-26, which summarises the IMO’s revised recommendations for entering enclosed spaces aboard ships.

Entering enclosed spaces remains one of the most dangerous tasks on board, and fatalities continue to occur. In response, the IMO adopted revised recommendations, Resolution MSC.581(110), which took effect on 3 December 2025. They replace the long-standing Resolution A.1050(27).

TAN 005-26, which was issued on 28 September 2026, highlights the key changes and how the Registry expects them to be applied.

Who it applies to

The notice applies to all Isle of Man registered ships, regardless of type or size. It is relevant to shipowners, managers and operators, Masters and seafarers, and shore personnel working on board under the ship’s safety management arrangements.

Guidance, linked to existing obligations

The revised recommendations do not introduce new mandatory requirements. However, they support existing obligations under SOLAS and the International Safety Management (ISM) Code. The Registry strongly encourages owners and operators to implement them in full, as they represent the latest IMO-endorsed best practice.

The key changes to Enclosed Space Entry

• Clearer definitions: New terms include connected and adjacent spaces, trapped hazardous atmospheres and the competent and responsible person. Hazards can move from one space to another.
• Stronger safety management: Owners and operators are expected to show clear leadership and accountability. Crew are explicitly empowered to stop or refuse entry when conditions are unsafe.
• An Enclosed Space Register: Each vessel should keep a ship-specific register of its enclosed spaces. It should be reviewed regularly and updated as the vessel, its cargoes or its operations change.
• Better atmospheric testing: Gas detectors should measure carbon dioxide (CO₂) as well as oxygen, flammable and toxic gases. CO₂ must be below 0.5% (5,000 ppm) before entry, and at least two sets of gas detection equipment are required.
• Tighter entry controls: Single-person entry is prohibited, permits have defined validity periods, and access points should be secured and signed. Emergency Escape Breathing Devices are not suitable for enclosed space entry.
• Planned rescue: Each vessel should have its own emergency response plan. Unplanned rescue attempts are strongly discouraged, and drills should reflect realistic scenarios.

Recommended actions

The Registry advises owners, managers and Masters to:

1. Review and update safety management systems, procedures and risk assessments.
2. Establish and maintain an Enclosed Space Register.
3. Check that gas detection equipment is suitable and that the correct number of sets is carried.
4. Align entry permits and rescue plans with the revised recommendations.
5. Make sure crew training and drills reflect the new guidance.

How Sentient can help

Sentient International’s Maritime team supports owners and managers with the structuring, registration, and administration of their vessels, whether used privately, commercially or a combination of both.

We also share the latest guidance and technical notices to ensure that those working onboard Isle of Man flagged vessels are aware of any changes to legislation, regulation and health & safety standards.

For more information on our services, please contact info@sentientinternational.com or phone +44 1624 616544.

Source: Isle of Man Ship Registry, Technical Advisory Notice 005-26. This article is a summary only. Please read the full notice for detailed requirements, including Appendix 1 on gas detectors.