Maritime Glossary
Plain-language definitions of the terms that move maritime markets, risk and careers — from war-risk premiums and chokepoints to STCW, MLC 2006 and allotments. One reference for owners, charterers, insurers and seafarers.
Educational reference only — verify operational guidance with UKMTO, MSCHOA, your flag state, P&I club and legal counsel.
Risk & markets
Vocabulary for transit risk, insurance and freight.
- Chokepoint
- A narrow, strategically critical stretch of water that concentrates global shipping.
- A constricted maritime passage — such as the Strait of Hormuz, the Bab-el-Mandeb, the Suez Canal, the Panama Canal, the Turkish Straits or the Malacca Strait — through which a large share of world seaborne trade or energy must pass. Disruption at a chokepoint forces costly re-routing and ripples through freight rates, insurance and supply chains.
- Dark fleet (shadow fleet)
- Aging tankers that obscure ownership and switch off tracking to move sanctioned cargo.
- A loosely defined group of typically older tankers that carry sanctioned or grey-market oil while concealing their activity — frequently disabling or spoofing their AIS transponders, conducting ship-to-ship transfers at sea, flying flags of convenience and rotating through opaque ownership structures. The fleet raises safety, environmental and compliance risks because vessels often carry substandard insurance.
- P&I (Protection & Indemnity) club
- A mutual association that covers a shipowner's third-party liabilities.
- A non-profit mutual insurer, owned by its shipowner members, that covers liabilities not handled by hull-and-machinery cover — crew injury and illness, cargo loss or damage, pollution, collision liability, wreck removal and repatriation. The major clubs belong to the International Group, which pools large claims among members.
- VLCC / Suezmax / Aframax
- Standard crude-tanker size classes, from very large down to medium.
- Crude carriers are grouped by capacity. A VLCC (Very Large Crude Carrier) holds roughly 2 million barrels; a Suezmax (about 1 million barrels) is the largest that can transit the Suez Canal laden; an Aframax (around 600,000–800,000 barrels) is sized to the Average Freight Rate Assessment trade. Above the VLCC sits the rarer ULCC. The classes set which berths, canals and routes a ship can use.
- Demurrage
- Money the charterer pays the owner when loading or discharge runs past the agreed laytime.
- A penalty rate, agreed in the charter party, that compensates the shipowner for a vessel being detained at port beyond the free 'laytime' allowed for cargo operations. Its opposite is despatch — a reward paid to the charterer for finishing early. Demurrage is one of the most commonly disputed items in dry-bulk and tanker shipping.
- Laytime
- The free time allowed under a charter for loading or unloading cargo.
- The period the charterer is permitted, without extra charge, to load or discharge the vessel. Laytime begins when a valid Notice of Readiness is tendered and accepted. Once it is used up, the vessel goes 'on demurrage'. How laytime counts — and what suspends it (weather, holidays, breakdowns) — is set by the charter party.
- AIS (Automatic Identification System)
- A transponder system that broadcasts a ship's identity, position and course.
- A VHF-based system that continuously transmits a vessel's MMSI identity, position, speed and heading to nearby ships and shore stations for collision avoidance and traffic management. Because the signal is open, AIS also underpins commercial vessel-tracking — which is why 'going dark' (switching it off) is a red flag for sanctions evasion.
- Flag of convenience
- Registering a ship in a country other than the owner's for cost or regulatory reasons.
- The practice of registering a vessel under the flag of a state — such as Panama, Liberia or the Marshall Islands — different from that of its beneficial owner, typically to reduce cost, tax or regulatory burden. Open registries dominate world tonnage; the flag state is responsible for enforcing safety, labour and environmental standards aboard.
- UKMTO
- The UK naval body that channels merchant-shipping risk reports in the Middle East region.
- The United Kingdom Maritime Trade Operations office acts as the primary point of contact between merchant vessels and military forces in the Gulf, Red Sea and Indian Ocean. Ships report movements and incidents to UKMTO, which issues advisories and warnings. Together with MSCHOA and flag-state guidance it is a core source for transit-risk decisions.
- Sanctions / SDN list
- Government measures restricting dealings with named entities, vessels or cargoes.
- Restrictions imposed by bodies such as the US Office of Foreign Assets Control (OFAC), the EU or the UN that prohibit transactions with designated parties. OFAC's Specially Designated Nationals (SDN) list can name individual ships, forcing insurers, flags and ports to cut ties. Sanctions compliance is now central to chartering, payments and insurance in shipping.
Seafarers & manning
Vocabulary for crew rights, training and contracts.
- STCW
- The international convention setting minimum training and certification for seafarers.
- The Standards of Training, Certification and Watchkeeping convention defines the qualifications, sea-time and competency certificates a seafarer must hold for a given rank. STCW courses (basic safety, advanced firefighting, survival craft and more) carry expiry dates, so certificate revalidation is a recurring part of a mariner's career.
- MLC 2006
- The 'seafarers' bill of rights' — minimum living and working standards at sea.
- The Maritime Labour Convention, 2006 sets baseline rights for crew: a written employment agreement, regulated hours of work and rest, wages, leave, repatriation, medical care, accommodation and access to complaint procedures. Ships are inspected and carry a Maritime Labour Certificate; port state control can detain vessels for serious breaches.
- POEA-SEC / DMW contract
- The standard Philippine employment contract governing Filipino seafarers.
- The Standard Employment Contract administered by the Philippine Department of Migrant Workers (DMW, successor to the POEA) sets the minimum terms for Filipino seafarers on ocean-going ships — wages, hours, leave, and crucially the schedule of disability and death compensation. It is read together with any applicable IBF/ITF collective bargaining agreement.
- Allotment
- The portion of a seafarer's wage sent home automatically to family.
- A standing arrangement under which part of a seafarer's monthly pay is remitted directly to a nominated beneficiary ashore, usually family. Allotments are a contractual right under most standard contracts and CBAs, and are a primary channel for the remittances that seafaring economies depend on.
- Repatriation
- The seafarer's right to be returned home at the employer's cost in defined circumstances.
- The entitlement of a crew member to be sent home — at no cost to themselves — at the end of contract, in case of illness or injury, on sale or loss of the ship, or when the employer cannot meet its obligations. Repatriation rights are protected under MLC 2006 and backed by mandatory financial security, with P&I clubs frequently involved.