mlees
Posts: 2263
Joined: 9/20/2003 From: San Diego Status: offline
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quote:
ORIGINAL: po8crg Mostly, the units are the same, feet, inches, yards and miles are the same in Britain as in the USA; pounds and ounces are the same, but our ton is 2,240 lb, to your 2,000 lb. Of course, the tons ships are measured in are completely different anyway - they're 100 cu. ft. Gross Tonnage is the relevant measure for military ships. All of the measures of fluid volume, from fluid ounce to pint to gallon are completely different between the two systems. It's my understanding that warships were measured in "Displacement" tons. (The weight of the seawater displaced by a ship.) Cite: http://en.wikipedia.org/wiki/Tonnage Quote from cite: quote:
Displacement is the actual total weight of the vessel. It is often expressed in long tons or in metric tons, and is calculated simply by multiplying the volume of the hull below the waterline (ie. the volume of water it is displacing) by the density of the water. (Note that the density will depend on whether the vessel is in fresh or salt water, or is in the tropics, where water is warmer and hence less dense.) For example, in sea water, first determine the volume of the submerged portion of the hull as follows: Multiply its length by its breadth and the draft, all in feet. Then multiply the product thereby obtained by the block coefficient of the hull to get the hull volume in cubic feet. Then multiply this figure by 64 (the weight of one cubic foot of seawater) to get the weight of the ship in pounds; or divide by 35 to calculate the weight in long tons. Using the SI or metric system : displacement (in tonnes) is volume (in m3) multiplied by the specific gravity of sea water (1.025 nominally). The word "displacement" arises from the basic physical law, discovered by Archimedes, that the weight of a floating object equates exactly to that of the water which would otherwise occupy the "hole in the water" displaced by the ship. Cargo ships probably use the GRT method. The Washington Naval Treaty defined a ton as 2240 pounds (weight, not volume), in Part 4: Definitions, here: http://www.ibiblio.org/pha/pre-war/1922/nav_lim.html Or am I misunderstanding something?
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