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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.
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 ...
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 ...
The Cruising Club of America (CCA) put together a technical committee that analyzed race boat data. They came up with the formula to compare boats based on readily available data. The CCA characterizes the formula as "rough". A lower value is supposed to indicate a sailboat is less likely to capsize. A value of 2 is taken as a cutoff for ...
The process of determining the PHRF for an individual boat begins with the regional PHRF rating, then adjustments are made for the individual attributes of the boat such as: modifications to the rig, the size of the largest foresail (jib or genoa), the size of the spinnakers, type of keel (full, fin, wing etc.), the number of blades on the propeller, and the style of the propeller (fixed ...
In particular, any "displacement" or non-planing boat requires much greater power to accelerate beyond its hull speed, which is determined by the length of the waterline, and can be calculated using the formula: Vmax (in knots) = square root of LWL (in feet) x 1.34. The hull speed is the speed at which the wavelength of the bow wave stretches ...
The maximum speed provided by the motor is 5.0 kn (9.3 km/h), while the design has a hull speed of 5.52 kn (10.22 km/h). [2] [3] For sailing the design is equipped with a self-tacking Hoyt jib boom system and a roller furling jib. The loose-footed mainsail is full-battened and stowed on the boom with standard lazy jacks. All lines are led under ...
The boat has a draft of 3.00 ft (0.91 m) with the centerboard extended and 4 in (10 cm) with it retracted, allowing operation in shallow water, beaching or ground transportation on a trailer. [1] [2] The design has a hull speed of 4.92 kn (9.11 km/h). [2]