- Deadweight tonnage (DWT)
- Total weight a vessel can carry — cargo plus fuel, stores, water and crew — at its assigned load line. It is a capacity measure, not a weight of the ship, and it is the number cargo vessels are usually sized by.
- TEU
- Twenty-foot equivalent unit, the standard container count. A 40-foot box is two TEU. Ship capacity, terminal throughput and port rankings are all quoted in TEU, which is why a 'bigger' ship in TEU may still be draft-limited at your berth.
- Draft and air draft
- Draft is depth below the waterline; air draft is height above it. Draft is governed by channel depth and tide, air draft by bridges and crane clearance. Either one can bar a vessel from a berth no matter what the cargo plan says.
- LOA and beam
- Length overall and maximum width. With draft they define whether a vessel fits a lock, a canal, a berth and a turning basin — the physical envelope every port publishes and every charterer checks first.
- Panamax, Neopanamax, Suezmax, Aframax
- Size classes defined by the waterways and trades a vessel can serve: the old and expanded Panama Canal locks, the Suez Canal, and (for Aframax) a tanker size historically tied to a freight-rate structure. They are commercial shorthand for where a hull can trade.
- Container ship
- Cellular vessel carrying standardised boxes on a fixed liner schedule. Economics turn on slot cost, utilisation and port rotation rather than on individual cargo deals.
- Bulk carrier
- Single-deck vessel for homogeneous dry cargo — grain, coal, iron ore, aggregates, fertiliser. Traded largely on the spot and period market, with hold cleanliness and cargo-hold surveys a routine commercial risk.
- Tanker (crude, product, chemical)
- Liquid cargo vessels segregated by what they may carry and how clean the tanks must be. Coating, heating, segregation and prior-cargo history determine what a charterer will accept, and vetting inspections gate the fixture.
- LNG carrier
- Purpose-built cryogenic vessel moving liquefied natural gas at about minus 162 degrees Celsius, with containment-system types, boil-off management and long-term project charters that make it the least spot-like segment in shipping.
- Ro-ro and PCTC
- Roll-on/roll-off vessels loaded by ramp, including pure car and truck carriers. Lane metres, not TEU or tonnes, are the capacity unit, and stowage is a driving exercise rather than a crane exercise.
- Tug and barge (towboat, tugboat)
- The workhorse of US domestic waterborne trade: towboats push barge tows on rivers and the Gulf Intracoastal, tugs tow or push astern on coastwise runs. Cheap per tonne-mile, slow, and heavily regulated under subchapter M.
- ATB (articulated tug-barge)
- A tug mechanically coupled into a notch in a barge's stern so the pair behaves much like a self-propelled ship, with a smaller crew and different regulatory treatment. Common in US coastwise petroleum and chemical trades.
- OSV and PSV
- Offshore support vessel is the umbrella term; a platform supply vessel is the cargo-and-deck-space variant that runs fuel, water, mud, cement and containers to offshore installations. Anchor handlers, liftboats and construction vessels sit alongside them.
- Voyage charter
- The owner is paid a freight rate to carry a stated cargo between stated ports and bears the voyage costs — fuel, port charges, canal dues. The charterer's exposure is concentrated in laytime and demurrage at each end.
- Time charter
- The charterer hires the vessel and crew for a period at a daily hire rate and pays the voyage costs, directing where the ship trades within agreed limits. Off-hire clauses decide who eats the time when the vessel cannot perform.
- Bareboat charter (demise)
- The charterer takes the bare vessel and supplies crew, insurance and operation, effectively becoming the disponent owner. Used for finance structures and for flag or Jones Act arrangements as much as for trading.
- Contract of affreightment (COA)
- A commitment to move a stated quantity of cargo over a period in a series of shipments, with the owner free to nominate vessels. It gives the shipper volume certainty and the owner a base load without tying up one specific hull.
- Charter party
- The contract itself, usually a standard form — GENCON, NYPE, SHELLTIME, ASBATANKVOY and their relatives — heavily amended by a rider. Most maritime disputes are decided by the rider clauses, not the printed form.
- Laytime, demurrage and despatch
- Laytime is the free time allowed for loading and discharge; demurrage is liquidated damages when it is exceeded; despatch is the reward, often half the demurrage rate, when the charterer finishes early. Notice of readiness starts the clock, and when the clock started is the argument.
- Freight rate and Worldscale
- The price for carrying cargo. In tankers it is commonly expressed as a percentage of Worldscale, a published nominal rate schedule for thousands of voyage routes that lets a single number be compared across different trades.
- Bunkers and bunker adjustment factor (BAF)
- Bunkers are the vessel's fuel and the largest single voyage cost. BAF is the surcharge mechanism liner carriers use to pass fuel-price movement to shippers, which is why an all-in quote and a base rate are not the same conversation.
- Slow steaming
- Running below design speed to cut fuel burn, since consumption rises steeply with speed. It absorbs surplus capacity, lowers emissions per tonne-mile and improves a carbon intensity rating — at the cost of transit time and working capital tied up in cargo.
- Ballast leg
- A voyage run empty to reposition for the next cargo. Ballast time and fuel are real costs with no revenue against them, and a voyage estimate that ignores the ballast leg will always look better than the fixture actually is.
- Time charter equivalent (TCE)
- Voyage revenue less voyage costs, divided by the days of the voyage — the daily figure that makes a voyage charter comparable with a time charter. The single most-used number in commercial ship operation.
- OPEX per day
- Daily running cost of the vessel regardless of employment: crew, stores, lubricants, routine maintenance, insurance and management fees. Set against TCE it shows whether the ship is earning or bleeding.
- Drydock and the special survey cycle
- Class requires periodic drydocking and a special survey typically every five years, with intermediate surveys in between. Yard slot availability, steel renewal and the days out of service are budgeted years ahead because off-hire during drydock is pure lost revenue.
- Classification society and class notation
- A class society sets and verifies structural and machinery standards and issues the certificates insurers and charterers rely on. Notations record what the hull is built and equipped for — ice class, dynamic positioning, cargo types — and they constrain what work the vessel can take.
- Flag state and port state control
- The flag state is the country of registry, responsible for the vessel's statutory compliance; port state control is the inspection regime a foreign port applies on arrival. A detention by port state control stops the ship and shows up on public performance lists.
- Jones Act, coastwise trade and cabotage
- Section 27 of the Merchant Marine Act of 1920 reserves waterborne cargo between two US points to vessels built in the US, US-flagged, and US-owned and crewed. It is the single largest structural fact in the domestic market and it shapes fleet age, newbuild pricing and every waiver argument.
- Seafarer credentials and safe manning
- US mariners hold a Merchant Mariner Credential with endorsements earned through sea time, examination and STCW training; the vessel's safe manning or minimum crew document sets who must be aboard. Sailing short of the document is not a scheduling problem, it is a detention.
- ISM Code and the safety management system
- The International Safety Management Code requires a documented safety management system, a designated person ashore, drills, audits and non-conformity reporting, evidenced by a Document of Compliance for the company and a Safety Management Certificate for the ship.
- ISPS Code and security levels
- The International Ship and Port Facility Security Code sets ship and facility security plans, security officers and three escalating security levels. Level changes drive access control, screening and guard requirements at the terminal gate as much as on board.
- MARPOL Annexes and the IMO 2020 sulphur cap
- MARPOL's six annexes cover oil, noxious liquids, packaged harmful substances, sewage, garbage and air emissions. Annex VI capped marine fuel sulphur at 0.50% globally from January 2020, with 0.10% inside emission control areas — met by compliant fuel or by scrubbers.
- EEXI and CII
- The Energy Efficiency Existing Ship Index is a one-off design-efficiency requirement; the Carbon Intensity Indicator is an annual operational rating from A to E based on emissions per transport work. Repeated poor ratings require a corrective action plan, and charterers have begun writing rating expectations into the fixture.
- EU ETS for shipping and FuelEU Maritime
- The EU Emissions Trading System was extended to shipping from January 2024, phasing in surrendering of allowances for voyages touching the EU; FuelEU Maritime applied from January 2025 with declining greenhouse-gas intensity limits on energy used on board. Both turn carbon into a line item and a charter-party allocation question.
- Ballast water management and treatment
- The Ballast Water Management Convention and the US Coast Guard's parallel rules require approved treatment systems and record-keeping to stop invasive species transfer. System type-approval, operability in silty coastal water and sampling on inspection are the practical problems.
- P&I club and hull and machinery insurance
- Hull and machinery covers physical damage to the ship; a protection and indemnity club, a mutual of shipowners, covers third-party liabilities — crew injury, pollution, cargo claims, wreck removal. Cover is conditional on class and on compliance, which is why a class suspension is an insurance event.
- General average
- The ancient principle that when a sacrifice or extraordinary expenditure is made to save the whole venture, ship and all cargo interests share the loss proportionally. Declared after events like a fire or grounding, it can hold cargo until security is posted, and it is adjusted under the York-Antwerp Rules.
- Salvage and Lloyd's Open Form (LOF)
- Salvage rewards a volunteer who saves property at sea. Lloyd's Open Form is the no-cure-no-pay contract a master can agree in minutes without settling price, with the award fixed later in arbitration — the reason it gets signed while the casualty is still developing.
- Bill of lading
- Simultaneously a receipt for the cargo, evidence of the contract of carriage and, when negotiable, a document of title. Clean versus claused, straight versus order, original versus sea waybill — the choice decides who can lawfully take delivery.
- Charterer, shipper and NVOCC
- The charterer hires the vessel, the shipper owns the cargo being moved, and a non-vessel-operating common carrier issues its own bills of lading while buying space from a vessel operator. Confusing these three is how liability lands on the wrong party.
- FMC licensing and ocean transportation intermediaries
- The Federal Maritime Commission licenses ocean transportation intermediaries — NVOCCs and ocean freight forwarders — requiring bonding and published or negotiated rate arrangements for US trades. Operating unlicensed in US ocean commerce is an enforcement matter, not a technicality.
- Terminal handling charge (THC)
- The terminal's charge for moving a container between the ship and the yard gate, billed by the carrier at origin and destination. It is the most common surprise on an ocean quote and a standing source of shipper disputes about what 'all-in' means.
- Detention and demurrage under OSRA
- Port demurrage is charged for cargo left in the terminal, detention for equipment kept outside it. The Ocean Shipping Reform Act of 2022 and the FMC's billing rule govern who may be invoiced, what an invoice must contain and the window to dispute it — charges must relate to a real incentive to move cargo.
- Berth window and crane moves per hour
- A berth window is the slot a service is guaranteed at a terminal; crane moves per hour is the productivity that decides whether the ship keeps it. Missing a window cascades into the whole rotation, so productivity is a commercial term, not just an operations metric.
- Dwell time and the drayage interface
- Dwell is how long a container sits in the terminal before it moves inland; the drayage interface is the trucking, appointment system and chassis supply that clears it. Terminal fluidity usually fails on the landside, not at the crane.
- Dredging and channel depth
- Authorised versus maintained depth, project depth, air draft under bridges, turning basin width and the maintenance dredging cycle. The Army Corps of Engineers holds the federal channel, and a channel a foot shallower than advertised is a loading restriction and a demurrage argument.