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Hull speed or displacement speed is the speed at which the wavelength of a vessel's bow wave is equal to the waterline length of the vessel. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest-to-trough dimension (height) increases as well. When hull speed is exceeded, a vessel in displacement mode ...
A polar diagram, or polar plot, is a graph that shows a sailboat's potential speed over a range of wind speeds and relative wind angles. [1] It normally consists of the right side of a line chart with the radius representing the yacht speed and the angle representing the wind direction blowing from top to bottom. Several lines are normally ...
A velocity prediction program (VPP) is a computer program which solves for the performance of a sailing yacht in various wind conditions by balancing hull and sail forces. VPPs are used by yacht designers, boat builders, model testers, sailors, sailmakers, also America's Cup teams, to predict the performance of a sailboat before it has been built or prior to major modifications.
Forward resistance comprises the types of drag that impede a sailboat's speed through water (or an ice boat's speed over the surface) include components of parasitic drag, consisting primarily of form drag, which arises because of the shape of the hull, and skin friction, which arises from the friction of the water (for boats) or air (for ice ...
A vessel's length at the waterline (abbreviated to L.W.L) [1] is the length of a ship or boat at the level where it sits in the water (the waterline). The LWL will be shorter than the length of the boat overall (length overall or LOA) as most boats have bows and stern protrusions that make the LOA greater than the LWL. As a ship becomes more ...
Most boats have a positive PHRF rating, but some very fast boats have a negative PHRF rating. If Boat A has a PHRF rating of 15 and Boat B has a rating of 30 and they compete on a 1 mile course, Boat A should finish approximately 15 seconds in front of Boat B. Results are adjusted for handicap by the race committee after all competitors have ...
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. [1] 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. [2]
The sail area-displacement ratio (SA/D) is a calculation used to express how much sail a boat carries relative to its weight. [1]/ = [() /] = () In the first equation, the denominator in pounds is divided by 64 to convert it to cubic feet (because 1 cubic foot of salt water weights 64 pounds).