Why Conventions Exist — and Why You Are Personally Accountable
IMO conventions arise because the sea is international. A yacht flagged in the British Virgin Islands, chartered in Monaco, crewed by Australians, and anchoring in Croatia operates across multiple jurisdictions simultaneously. Flag States give domestic legal force to IMO conventions through their own legislation; for UK-flagged yachts, that pathway runs through the Merchant Shipping Act 1995 and the statutory instruments and codes beneath it — including MSN 1858, which sets out the certificates and requirements applicable to your vessel.
As Master, you are not a passive carrier of paperwork. The convention obligations land on you personally: SOLAS places duties directly on the master, not merely on the company.
The Two Pillars: SOLAS and MARPOL
SOLAS (Safety of Life at Sea, 1974 as amended) is the primary instrument for vessel and crew safety. For yachts under 500 GT operating commercially, the chapters most relevant at command level are:
- Chapter II-1: Construction, subdivision, stability — informs your stability booklet obligations and damage stability awareness
- Chapter II-2: Fire protection, detection and extinction — drives your fire safety system requirements and the 60 °C minimum flash point for fuel
- Chapter III: Life-saving appliances and arrangements — drills, equipment maintenance, muster lists
- Chapter IV: Radio communications — GMDSS carriage and watch obligations
- Chapter V: Safety of navigation — steering gear tests, passage planning, IAMSAR carriage, the master's duty to render assistance
- Chapter IX: ISM Code — your SMC, the company's DOC, your obligations as the master under the SMS
MARPOL 73/78 governs prevention of pollution from ships. The annexes that routinely affect a yacht Master:
- Annex I (oil): the 15 ppm rule, the Oil Record Book, IOPP certificate for vessels ≥400 GT
- Annex II: noxious liquid substances — limited relevance to most yachts
- Annex IV: sewage — holding tank requirements, discharge restrictions in Special Areas and port waters
- Annex V: garbage — the Garbage Management Plan, Garbage Record Book (now ≥100 GT or 15+ persons from 1 May 2024), Special Areas including the Mediterranean and Red Sea
- Annex VI: air pollution — sulphur limits (0.50% global, 0.10% in ECAs; Mediterranean became a SOx ECA 1 May 2025), the Bunker Delivery Note retained three years
The Command Decision
At the oral, the examiner is testing whether you understand why a rule exists, not just that it exists. When asked about MARPOL Annex V Special Areas, the answer that passes at command level links the geographic boundary to an operational decision: you identify the area on passage, you confirm your garbage management plan reflects the prohibition, and you know what record must be kept and for how long. The same logic applies to SOLAS V/33 — you don't just know the duty to render assistance exists; you know it falls on you as master the moment you receive information from any source, and you know what the log must contain if you cannot comply.