Search results
Results from the WOW.Com Content Network
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 ...
Sailing hydrofoils achieve boat speeds up to twice the speed of the wind, as did the AC72 catamarans used for the 2013 America's Cup. [20] Ice boats can sail up to five times the speed of the wind. [21] [22] Lateral force is a reaction supplied by the underwater shape of a sailboat, the blades of an ice boat and the wheels of a land sailing craft.
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).
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.
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]
It can thus be shown that the forces (F) must be at the same scale as the masses and weights, so: S (F) = S (M) = 25 3 = 15 625 Similitude of speed(V): In agreement with Froude's law, the velocity scale is the square root of the length scale, so: S (V) = S 1/2 (L) = sqrt(25) = 5 (times slower than in real life)
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 ...
A navigator who needed to know the speed of the vessel had a sailor drop the log over the ship's stern. The log acted as a drogue , remaining roughly in place while the vessel moved away. The sailor let the log-line run out for a fixed time while counting the knots that passed over.