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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 ...
High-performance watercraft that can exceed the speed of the true wind include sailing catamarans and foiling sailing craft. Ice boats and land-sailing craft are often able to do so. There are also wind-powered vehicles that can travel faster than the wind, such as the rotor-powered Blackbird, which are outside the scope of this article.
This nomenclature dates back to the days of sail, when sailors attached a piece of lumber (a "log" of wood) to a rope knotted at regular intervals off the stern of a ship. Sailors counted the number of knots that passed through their hands in a given time to determine the ship's speed. Today, sailors and aircraft pilots still express speed in ...
I wish the term hull speed would go away. It is the most misunderstood and misused term among amateur boat users. Hull speed is a special case of a speed-length ratio These are just two different terms for the same idea applied for the specific case of a vessel when the waterline length equals the wavelength of a transverse bow wave.
The boat has a draft of 4.26 ft (1.30 m) with the standard keel fitted. The Oceanis 321 is fitted with a Swedish Volvo diesel engine. The fuel tank holds 16 U.S. gallons (61 L; 13 imp gal) and the fresh water tank has a capacity of 72 U.S. gallons (270 L; 60 imp gal). [1] [3] The boat has a hull speed of 7.26 kn (13.45 km/h). [3] [6]
The boat has a draft of 5.25 ft (1.60 m) with the standard keel and 3.83 ft (1.17 m) with the optional wing keel. An optional tall rig has a mast about 2 ft (0.61 m) taller. The boat has a hull speed of 6.7 kn (12.41 km/h). [15] Catalina 30 Mark III This model was built between 1990-2008 and was designed by Gerry Douglas.