(www.MaritimeCyprus.com) Enclosed spaces aboard ships—such as cargo holds, ballast tanks, cofferdams, double bottoms, and duct keels—are routinely cited as major causes of fatalities in the maritime sector. The atmosphere within these spaces can rapidly become lethal due to a host of hidden hazards, most critically: oxygen depletion (often caused by oxidation, rust, or biological activity), oxygen enrichment, or the presence of toxic (e.g., hydrogen sulphide, carbon monoxide) or flammable gases. Tragically, a large percentage of these accidents involve not the original entrant, but the subsequent rescuers who attempt to retrieve the initial casualty without following proper safety protocols, highlighting the paramount need for stringent, updated procedures. The IMO's revision of these recommendations is a direct response to the continued, preventable loss of life that results from these dangerous environments.
The maritime industry is on the cusp of a significant safety overhaul following the adoption of Resolution MSC.581(110) – REVISED RECOMMENDATIONS FOR ENTERING ENCLOSED SPACES ABOARD SHIPS. Approved by the IMO Maritime Safety Committee (MSC 110) on June 27, 2025, this new resolution marks a comprehensive revision of procedures, superseding the longstanding Resolution A.1050(27).
The incoming regulation, which addresses the continued loss of life in shipboard spaces, fundamentally shifts the focus of accident prevention. The Preamble of MSC.581(110) states that casualties are caused not merely by a lack of guidance, but by failing to conduct proper risk assessments and implement appropriate procedures. It explicitly recognizes that organizational leadership is crucial for successful implementation by empowering shipboard staff.
Shipowners and operators are strongly advised to immediately review and revise their Safety Management Systems (SMS) to reflect the new requirements ahead of the 34th session of the IMO Assembly (24 November – 3 December 2025), which will officially revoke Resolution A.1050(27).
Key Changes for Safety Management Systems (SMS)
Resolution MSC.581(110) introduces several new concepts, clarifies responsibilities, and expands the scope of the recommendations:
Expanded Scope and Responsibility
The new recommendations significantly expand their coverage, now explicitly including port and terminal operators, port workers, and operations involving shore personnel on board. This necessitates implementing new safety management measures to cover shore-ship interfaces.
Key measures related to shore personnel include:
Conducting a pre-operational risk assessment and, where hazards are identified, a joint risk assessment with terminal representatives.
Placing a basic schematic plan of the ship’s spaces at the gangway or access points, clearly indicating safe and unsafe spaces for entry.
Providing shore personnel with information on enclosed space hazards that may be present on the ship.
New Definitions and Hazards
The resolution introduces critical new terminology to enhance hazard identification:
Connected Space: A newly defined term, a connected space (e.g., separated by a manual door) must be treated as containing a hazardous atmosphere until testing proves otherwise.
Adjacent Space: The definition is clarified, with the implication that almost every space other than the accommodation block may be considered an adjacent space.
Trapped Hazardous Atmosphere: A new definition and requirement, addressing a hazardous atmosphere that may be contained in a connected space even after the source space is discharged.
The Enclosed Space Register
A pivotal new requirement is the Enclosed Space Register. This is a ship-specific register that must list all enclosed spaces, along with their connected and adjacent spaces, their specific hazards, and the necessary risk mitigations.
Operational and Procedural Updates
The operational procedures for enclosed space entry have also been strengthened:
Risk Assessment: The competent person's assessment must now explicitly determine the potential for the presence of Carbon Monoxide (CO) and Carbon Dioxide () as well as other toxic or asphyxiant gases. The safe threshold for in gas readings is specified as less than 0.5% by volume or 5000 ppm.
Entry Permit Validity: The validity of an enclosed space entry permit is now strictly specified to be never longer than eight hours.
Securing Access: Entry doors or access hatches should at all times be secured against entry unless declared safe, with the suggestion that a system of seals similar to those in the ISPS Code may be used.
Prohibition on Solo Entry: MSC.581(110) mandates that the company must ensure single person entry into an enclosed space is not permitted.
Time Pressure: The company is required to ensure adequate time is allowed for enclosed space activities, as undue time pressure is recognized as a causal factor in accidents.
Training & Equipment: Crew members must be trained in the use of equipment necessary to facilitate rescue from an enclosed space, and a record of this training must be maintained.
The new Resolution MSC.581(110) represents a comprehensive step forward in maritime safety, emphasizing better planning, stricter control over access, and improved hazard identification, particularly with respect to hazardous gases and the involvement of shore personnel. Companies must act quickly to incorporate these fundamental changes into their safety management systems.
For more information, you can download below the new IMO Resolution MSC.581(110):
As additional Guidance to Owners/Managers, you can download below, a Comparison table between IMO A.1050(27) and the new MSC.581(110):
Source: IMO
