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Sail Area-Displacement Ratio
The Sail Area-Displacement ratio (SA/D) is a calculation used to express how much sail a boat carries relative to its weight. :\mathit = \frac = \frac 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). The denominator is taken to the 2/3 power to make the entire metric unit-less (without this, the denominator is in cubic feet, and the numerator is in square feet). It is an indicator of the performance of a boat. The higher the SA/D, the more lively the boat's sailing performance: SA/D, however, doesn't provide information about a boat behavior in a storm or upwind. A polar diagram from a velocity prediction program 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 ... gives a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sail Plan
A sail plan is a description of the specific ways that a sailing craft is rigged. Also, the term "sail plan" is a graphic depiction of the arrangement of the sails for a given sailing craft.> In the English language, ships were usually described, until the end of the eighteenth century, in terms of their type of hull design. Using the type of rig as the main type identifer for a vessel only became common in the nineteenth century. This is illustrated by the terminology for ships in the large fleet of colliers that traded to London from the coal ports of the Northeast of England (of which was a well-known example). Many of these full-rigged ships (square rigged on all of three masts) had the hull type "bark"another common classification was "cat". In the second half of the eighteenth century, the square sails on the mizzen were often eliminated. The resulting rig acquired the name of the hull type: initially as "bark" and soon as "barque". This explains the Royal Navy's descripti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailboat
A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture. Types Although sailboat terminology has varied across history, many terms have specific meanings in the context of modern yachting. A great number of sailboat-types may be distinguished by size, hull configuration, keel type, purpose, number and configuration of masts, and sail plan. Popular monohull designs include: Cutter The cutter is similar to a sloop with a single mast and mainsail, but generally carries the mast further aft to allow for a jib and staysail to be attached to the head stay and inner forestay, respectively. Once a common racing configuration, today it gives versatility to cruising boats, especially in allowing a small staysail to be flown from the inner stay in high winds. Catboat A catboat has a single mast mounted far forward and does not ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Displacement (ship)
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. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used. Ship displacement varies by a vessel's degree of load, from its empty weight as designed (known as "lightweight tonnage") to its maximum load. Numerous specific terms are used to describe varying levels of load and trim, detailed below. Ship displacement should not be confused with measurements of volume or capacity typically used for commercial vessels and measured by tonnage: net tonnage and gross tonnage. Calculation The process of determining a vessel's displacement begins with measuring its draft.George, 2005. p.5. This is accomplished by means of its "draft marks" (or "load lines"). A mer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocity Prediction Program
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. Background The first VPP was developed at the Massachusetts Institute of Technology during the early 1970s when Commodore H. Irving Pratt funded research to predict the performance ''"of a sailing yacht, given knowledge of its hull, rig and sailplan geometry"''. Methodology VPPs are iterative programs which require educated guesses of initial parameters to begin operating. Generally VPPs are composed of two mechanisms, a ''boat model'' and a ''solution algorithm''. Initial guesses of parameters including boat speed (Vs), heel angle (Φ), number of reefs and sail flatness are input into the ''bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Displacement–length Ratio
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 It is calculated by dividing a boat's displacement in long tons (2,240 pounds) by the cube of one one-hundredth of the waterline length (in feet): :\mathit = \frac DLR can be used to compare the relative mass of various boats no matter what their length. A DLR less than 200 is indicative of a racing boat, while a DLR greater than 300 or so is indicative of a heavy cruising boat. As shown in the 2 graphs in the kindle-sample of the 6th edition ( but not anywhere in the full-book of the 7th ) of Adlard Coles' "Heavy Weather Sailing", whether a given DLR is considered "heavy" or "light" *is entirely dependent on how big the boat is*. Those numbers in the table, above, match a boat of exactly 30.5' LWL. A boat of any other size will be "light" or "heavy" at a different DLR: a 10' LWL boat that is Ultralight is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Measurements
Ship measurements consist of a multitude of terms and definitions specifically related to ships and measuring or defining their characteristics. Definitions Beam - A measure of the width of the ship. There are two types: :Beam, Overall (BOA), commonly referred to simply as Beam - The overall width of the ship measured at the widest point of the nominal waterline. :Beam on Centerline (BOC) - Used for multihull vessels. The BOC for vessels is measured as follows: For a catamaran: the perpendicular distance from the centerline of one hull to the centerline of the other hull, measured at deck level. For a trimaran: the perpendicular distance between the centerline of the main hull and the centerline of either ama, measured at deck level. This term in typically used in conjunction with LOA (Length overall; see below). The ratio of LOA/BOC is used to estimate the stability of multihull vessels. The lower the ratio the greater the boat's stability. Carlin - similar to a beam, except ru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Terminology
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water (mostly though not necessarily on the sea). Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin ''nauticus'', from Greek ''nautikos'', from ''nautēs'': "sailor", from ''naus'': "ship". Further information on nautical terminology may also be found at Nautical metaphors in English, and additional military terms are listed in the Multiservice tactical brevity code article. Terms used in other fields associated with bodies of water can be found at Glossary of fishery terms, Glossary of underwater diving terminology, Glossary of rowing terms, and Glossary of meteorology. This glossary is split into two articles: * terms starting with the letters A to L are at Glossary of nautical terms (A-L) * terms starting with the letters M to Z are at Glossary of nautical terms (M-Z). __ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering Ratios
Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more specialized fields of engineering, each with a more specific emphasis on particular areas of applied mathematics, applied science, and types of application. See glossary of engineering. The term ''engineering'' is derived from the Latin ''ingenium'', meaning "cleverness" and ''ingeniare'', meaning "to contrive, devise". Definition The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET) has defined "engineering" as: The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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