Talk:HMS Approach/@comment-6335668-20141113063820/@comment-25652548-20141113100904

Technically, the Builder's Old Measurement could be used, but, since the ship info lacks data on it's overall depth or beam, it isn't possible to do the math to find out if the number is accurate or not.

Though, it is accurate to the terms that most First-Rate SOTL's back from the 1770s to 1900s had overall displacement weights of up to 5,500 tons or over, but displacement does not always translate to overall weight of a ship's tons burthen.

It can be safe to assume that the ship's tonnage is currently listed not only by the tons burthen by bm/bom, but also by a gross tonnage (gt) measurement. It should be noted that bm/bom was in use until steam propulsion was put into use, hence, bm/bom was retired, and a new Moorsom system was invented in it's place, where it became the general measurement for ships by law in the UK in 1855 (might be off a year).

If this is true, then by Moorsom system standards, then the tonnage is most likely correct, for the Moorsom system didn't only cover the weight of the ship itself, but also the internal volume, which would then be divided by 100 cubic feet to calculate a gross tonnage (gt), and then subtracting any of the volume used by facilities or machinery on board (such as quarters, or cannons, or in the case of a steam-powered vessel, the engine).

Since steam-powered vessels do exist (such as the icebreaker ships that sail to and from Northrend), the Moorsom system would come into play here.