::Builder's Old Measurement
::concepts
Builder's Old Measurement (BOM or bm) 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 based on length and maximum beam. It is expressed in "tons burden" (Early Modern English: burthen{{#invoke:Category handler|main}}, Middle English: byrthen {{#invoke:Category handler|main}}), and abbreviated "tons bm".
The formula is:
- <math> \text{Tonnage} = \frac {(\text{Length}- (\text{Beam}\times\frac{3} {5})) \times \text{Beam} \times \frac {\text{Beam}}{2}} {94}</math>
where:
- Length is the length, in feet, from the stem to the sternpost;
- Beam is the maximum beam, in feet.<ref name=Kemp>{{#invoke:citation/CS1|citation
|CitationClass=book }}</ref>
The Builder's Old Measurement formula remained in effect until the advent of steam propulsion. Steamships required a different method of estimating tonnage, because the ratio of length to beam was larger and a significant volume of internal space was used for boilers and machinery. In 1849, the Moorsom System was created in Great Britain. The Moorsom system calculates the cargo-carrying capacity in cubic feet, another method of volumetric measurement. The capacity in cubic feet is then divided by 100 cubic feet of capacity per gross ton, resulting in a tonnage expressed in tons.
Builder's Old Measurement sections
Intro History and derivation Depth American tons burthen See also References External links
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Times::length Tonnage::first Tonnage::cubic British::formula Burthen::capacity Depth::title
Builder's Old Measurement (BOM or bm) 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 based on length and maximum beam. It is expressed in "tons burden" (Early Modern English: burthen{{#invoke:Category handler|main}}, Middle English: byrthen {{#invoke:Category handler|main}}), and abbreviated "tons bm".
The formula is:
- <math> \text{Tonnage} = \frac {(\text{Length}- (\text{Beam}\times\frac{3} {5})) \times \text{Beam} \times \frac {\text{Beam}}{2}} {94}</math>
where:
- Length is the length, in feet, from the stem to the sternpost;
- Beam is the maximum beam, in feet.<ref name=Kemp>{{#invoke:citation/CS1|citation
|CitationClass=book }}</ref>
The Builder's Old Measurement formula remained in effect until the advent of steam propulsion. Steamships required a different method of estimating tonnage, because the ratio of length to beam was larger and a significant volume of internal space was used for boilers and machinery. In 1849, the Moorsom System was created in Great Britain. The Moorsom system calculates the cargo-carrying capacity in cubic feet, another method of volumetric measurement. The capacity in cubic feet is then divided by 100 cubic feet of capacity per gross ton, resulting in a tonnage expressed in tons.
Builder's Old Measurement sections
Intro History and derivation Depth American tons burthen See also References External links
PREVIOUS: Intro | NEXT: History and derivation |
<< | >> |