Navigation & Shipping

A unit of 100 cubic feet of enclosed space, entered in a ship’s certificate of registry.

100 cubic feet = 2.832 cubic metres

The total enclosed volume of a vessel, reckoned in register tons of 100 cubic feet.

Total enclosed space ÷ 100 cubic feet

Gross tonnage less permitted deductions for space that cannot carry cargo.

Gross tonnage minus engine, bunker and crew space

The total weight a vessel can carry when loaded to her deep-load line.

Long tons of 2,240 lb, or metric tonnes of 2,204.6 lb

The weight of water displaced by a hull, and therefore the weight of the ship itself.

Long tons of 2,240 lb

A freight ton of 40 cubic feet, used to charge for cargo that is bulky rather than heavy.

40 cubic feet = 1.133 cubic metres

Derived from Old English for outstretched arms, traditionally used for measuring water depth.

6 feet = 1.8288 metres

One tenth of a nautical mile, and originally the working length of a ship’s anchor cable.

185.2 metres = 607.6 feet

Derived from a minute of latitude on the Earth’s surface, and fixed internationally at 1,852 metres.

1,852 metres = 1.15078 statute miles = 6,076.1 feet

One nautical mile per hour, originating from counting knots on a ship’s log-line.

1 nautical mile per hour = 1.15078 mph = 1.852 km/h

One thirty-second of the horizon, used for steering and bearings before degrees.

11.25° = 11° 15′

A Royal Navy maritime tradition dividing evening hours into two short shifts.

2 hours