The full ISM Code is written for larger ships. Yachts under 500 GT are treated differently: the main yacht codes ask for a simpler safety management system, written for the yacht and its crew. Whether that system is compulsory depends on the flag and on whether the yacht is used commercially.
Red Ensign registers, including the UK and Cayman Islands
The REG Yacht Code Part A, chapter 23A, says: “All vessels under 500GT shall employ a safety management system”. It applies to commercial yachts under 500 GT. The system must be reviewed “at least once in every three years” (section 23A.16).
Marshall Islands
The Marshall Islands Yacht Code (MI-103), section 1.11.3, requires commercial yachts under 500 GT to “implement and maintain a mini-ISM system”, set out in its Annex 1. Marine Notice 2-011-49 adds that the system should be reviewed at intervals of no more than 12 months.
Malta
Malta’s Commercial Yacht Code 2025, section 21.1.5, strongly recommends a safety management system for commercial yachts under 500 GT rather than requiring one. A Recognised Organisation or authorised surveyor can audit the system and issue a Statement of Compliance.
Private yachts
For private yachts a safety management system is voluntary under all of these flags. Many owners still choose one, because it gives the crew clear procedures and gives the owner evidence that the yacht is run safely.
At a glance
| Flag | Use | Safety management system | Review |
|---|---|---|---|
| UK and other Red Ensign registers, including Cayman Islands (REG Yacht Code Part A) | Commercial, under 500 GT | Compulsory. Chapter 23A: “All vessels under 500GT shall employ a safety management system”. | At least once every three years (section 23A.16) |
| Marshall Islands (MI-103 Yacht Code) | Commercial, under 500 GT | Compulsory. Section 1.11.3: yachts under 500 GT must “implement and maintain a mini-ISM system” (Annex 1). | At intervals of no more than 12 months (MN 2-011-49, section 2.1.1) |
| Malta (Commercial Yacht Code 2025) | Commercial, under 500 GT | Recommended (voluntary). Section 21.1.5: the flag “strongly recommends” it; an RO or authorised surveyor may audit it and issue a Statement of Compliance. | Not fixed by the code; we suggest once a year |
| Private yachts (any of these flags) | Private use only | Voluntary. Many owners still choose one. | By choice; we suggest once a year |
What a small-yacht system contains
- A safety and environmental policy, and who is responsible for what on board and ashore
- The master’s overriding authority
- A named shore contact who can be reached at any time
- Emergency procedures and a drills programme
- Reporting of accidents, near misses and non-conformities, and how they are put right
- Maintenance of the yacht and its equipment, with records
- A regular review of the whole system
How we help
We write the system for yachts under 500 GT, set it up on board with the crew and keep it reviewed. See our small-yacht safety management service.
Sources
- Red Ensign Group, REG Yacht Code Part A, July 2024 edition, chapter 23A. https://www.redensigngroup.org/media/yzlbtkyi/reg-yc-july-2024-edition-part-a.pdf
- Republic of the Marshall Islands, MI-103 Yacht Code, Chapter II section 1.11 and Annex 1. https://www.register-iri.com/wp-content/uploads/MI-103-2021.pdf
- Republic of the Marshall Islands, Marine Notice 2-011-49, Mini-ISM for yachts under 500 GT. https://www.register-iri.com/wp-content/uploads/MN-2-011-49.pdf
- Transport Malta, Commercial Yacht Code 2025, section 21. https://www.transport.gov.mt/CYC-2025.pdf-f10643
Sources accessed October 2026. This is general information, not legal or regulatory advice; we confirm the rules for each yacht’s flag in writing before we start.