Thames Measurement, also known as Thames Tonnage, is a system for measuring ships and boats. It was created in 1855 as a variation of
Builder's Old Measurement
Builder's Old Measurement (BOM, bm, OM, and o.m.) is the method used in England from approximately 1650 to 1849 for calculating the cargo capacity of a ship. It is a volumetric measurement of cubic capacity. It estimated the tonnage of a ship bas ...
by the
Royal Thames Yacht Club, and was designed for small vessels, such as
yachts. It was originally used for calculating the port dues for yachts; the formula was also used in some early
handicapping
Handicapping, in sport and games, is the practice of assigning advantage through scoring compensation or other advantage given to different contestants to equalize the chances of winning. The word also applies to the various methods by which th ...
systems for
yacht racing.
The calculation of Thames Tonnage uses the following formula:
:
where:
*''length'' is the length, in
feet, from the stempost to sternpost;
*''beam'' is the maximum
beam
Beam may refer to:
Streams of particles or energy
*Light beam, or beam of light, a directional projection of light energy
**Laser beam
*Particle beam, a stream of charged or neutral particles
**Charged particle beam, a spatially localized grou ...
, in feet.
This can be simplified as:
:
See also
*
Tonnage
References
{{Yacht handicapping rules
Sailing rules and handicapping
Volume
Mass
Ship measurements