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The primary formula used to calculate the displacement of a ship is based on its physical dimensions and block coefficient. The block coefficient is a dimensionless number that describes how closely the shape of a ship resembles a rectangular block.
The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight.
The displacement–length ratio (DLR or D/L ratio) is a calculation used to express how heavy a boat is relative to its waterline length. DLR was first published in Taylor, David W. (1910). The Speed and Power of Ships: A Manual of Marine Propulsion. John Wiley & Sons. p. 99.
By Archimedes' principle, displacement mass is equal to displacement volume multiplied by the density of the water (nominally 1000 kg/m 3 or 62.4 lb/ft 3 for fresh water, 1025 kg/m 3 or 64 lb/ft 3 for seawater). This is the figure that should be used for all performance ratios and comparisons.
The prismatic coefficient is the ratio of actual underbody volume to the volume of a prism having a length equal to the DWL, and a section equal to the boat's maximum sectional area. The prismatic coefficient provides an indication of the distribution of displacement.
28 kwi 2010 · The complete formula is as follows: D/L = DLT ÷ (0.01 x LWL)³. As an example, to find the D/L ratio of a 12,000-pound boat with a load waterline length of 28 feet, you first divide 12,000 by 2,240 to find the boat’s displacement in long tons: 12,000 ÷ 2,240 = 5.36 long tons.
Calculation applies to all three body axes: x,y,z. x can be referenced to any point, e.g., bow, waterline, geometric center, etc. “Enclosed” water has to be included in the mass if we are talking about inertia. Center of Buoyancy. A similar differential approach with. displaced mass: b x = 6 ' ix i. ' where. ' is incremental volume, i.
