Glossary
A glossary of the maritime and routing terms used in PortReckon and in sea freight generally. The terms that appear directly in the tool are grouped first, followed by wider shipping vocabulary you are likely to meet when planning a voyage.
Terms used in this tool
- Nautical mile (nmi)
- The standard unit of distance at sea, equal to 1.852 km. It is based on one minute of latitude, which makes it convenient for chart work.
- Knot
- One nautical mile per hour, the standard unit of ship speed. A vessel doing 16 knots covers 16 nautical miles each hour.
- ETA (Estimated Time of Arrival)
- The expected arrival time at the destination, based on the route, speed, and delays. See How ETA Works.
- Transit time
- The total time a voyage takes between two ports, including sailing time and any fixed delays such as waiting for a berth.
- Waypoint
- An intermediate point between the origin and destination that the route must pass through - useful for forcing a voyage via a particular hub or strait.
- Shipping lane
- A commonly used sea route between regions. Routing in this tool follows real shipping lanes where possible instead of a straight line.
- Great-circle route
- The shortest path between two points on the surface of the globe. This tool uses it as a straight-line fallback when no sea lane can be found.
- Rhumb line
- A path of constant compass bearing. It is easy to steer but longer than a great-circle route over long distances.
- Dead reckoning
- Estimating a position or arrival from a known starting point plus speed, course, and elapsed time. It is the idea behind this tool's name.
- Chokepoint
- A narrow canal or strait, such as the Suez Canal or the Strait of Hormuz, that concentrates a large share of sea traffic. See Major Sea Routes.
- UN/LOCODE
- A United Nations Code for Trade and Transport Locations, a five-letter code identifying a port or place - for example, KRPUS for Busan, NLRTM for Rotterdam, and SGSIN for Singapore.
Wider shipping vocabulary
- Port of call
- A port where a ship stops during a voyage, to load or discharge cargo or to take on fuel and supplies.
- Transhipment
- Moving cargo from one ship to another at an intermediate hub port rather than carrying it all the way on a single vessel.
- Feeder vessel
- A smaller ship that carries containers between a large hub port and nearby regional ports, connecting them to the main long-haul services.
- TEU
- Twenty-foot Equivalent Unit, the standard measure of container capacity. One standard 20-foot container is one TEU; a 40-foot container is two.
- Deadweight tonnage (DWT)
- The total weight a ship can safely carry - cargo, fuel, water, and stores - expressed in tonnes.
- Draft (draught)
- How deep a ship sits in the water. It limits which ports, canals, and straits a loaded vessel can use.
- Bunker / bunkering
- Marine fuel, and the act of taking it on. Fuel cost is a major reason operators weigh distance against speed.
- Laytime and demurrage
- Laytime is the agreed time allowed for loading or discharging; demurrage is the charge that applies when that time is exceeded.
- Pilotage
- Navigation of a ship through confined or hazardous waters by a local pilot, often compulsory when entering or leaving a port.
- Cabotage
- The transport of goods between two ports in the same country, frequently restricted to nationally flagged vessels.
Routes are for planning/visualization only and are not certified for navigation.
This website is provided "as is", for general information and planning only, with no warranty of accuracy, completeness, or fitness for any purpose. To the fullest extent permitted by law, the operators of this website accept no responsibility or liability for any loss, damage, cost, or decision arising from use of the site or reliance on its routes, distances, or ETA estimates. Use at your own risk.