A catamaran cat for short is a multihulled watercraft consisting of two parallel hulls of equal size. Sails may be made from a combination of woven materialsincluding canvas or polyester cloth, laminated membranes or bonded filamentsusually in a three or foursided shape. Note that a sloop rig sail can achieve at best a maximum lift coe. Learn more sailfish yacht analyzer a velocity prediction program at a fraction of the cost for similar packages. The crab claw sail or, as it is sometimes known, oceanic lateen or oceanic sprit, is a triangular sail with spars along upper and lower edges. Computational and experimental study on performance of sails. The work of the yacht research group and tony marchaj. A sail plan is a set of drawings, usually prepared by a naval architect which shows the various combinations of sail proposed for a sailing ship. Aero hydrodynamics and the performance of sailing yachts available for download and. Why do yacht designers fit tbulbs to the keels of modern. Sail performance, techniques to maximize sail power, revised edition.
From his 40 years of research and windtunnel tests, acknowledged expert marchaj describes how these factors affect sail power and why certain rigs are superior in power and efficiency. Marchaj showed how unreliable inviscid vortex lattice meth ods may be as used by. Sailing performance results from a complex tradeoff between various design factors. Sail performance depends on a large number of param eters, such as. Usually this provides improved performance without any change in the user experience, but if the queried data is rapidly changing and its important for the user to see updated values, this pattern should be. This volume replaces marchaj s classic sailing theory and pactice, published 25 years ago, and offers new information on, rig design, sail construction and trim, windsail interaction, and the structure of the wind.
Sail shape figure 1b shows a cross section of a sail. This may seem strange in the light of racing yachts with huge overlapping genoas, but its the rule and not aerodynamics which calls the racing tune. Publication date 1980 topics sailboats, sailboats, sails publisher new york. Recently, i had the good fortune to spend the better part of a sunday in january on the water under sail. This is determined by the gap width between the head sail and the main sail. The author considers the factors which affect sail power.
There is a performance trade off between any hydrodynamic or stability advantage of the tbulb, and the time lost disentangling. The investigation emerged from the interest shown by designers and sail. Overlapping area in the genoa is free area for racing boats, so the more the better. Aerohydrodynamics of sailing by marchaj, czeslaw a. Effects of rig tension on sailing yacht performance. Pdf database of sail shapes versus sail performance and. Effects of rig tension on sailing yacht performance university of. The sail dynamometer system is composed of a rigid aluminum frame and four load cells. Sailboat parameter calculations and comparisons description. Historically, a ship was a sailing vessel with at least three squarerigged masts and a full bowsprit. Being ballast free and lighter than a monohull, a catamaran can have a very shallow draught. If this is in a sail interface, it will only run the slow query once. Everyday low prices and free delivery on eligible orders. The sailing performance of a yacht depends on the balance of hydro and aerodynamic forces acting on the hull and on the sails.
High speed sails 2 so easily driven that this power is not required in order to get it moving, it is best to place all sail area in a single, tall sail. Performance sailing products specializes in custom fabrication and small production runs of hardware for highperformance wind sports we have a number of standard products that we sell and we are always interested in helping with oneoff custom projects. The interaction between main sail and head sail only pays off if the head sail is allowed to perform effectively. These battens are tied into the sail with enough compressive force to bend them into the desired shape.
The crab claw sail consists of a sail, approximately an isosceles triangle in shape. Fully updated, this authoritative and richly illustrated standard reference offers the latest information on rig design, sail construction and trim, windsail interaction, and the structure of the wind. Jun 01, 1996 the performance of any sailing craft depends largely on the power of the available sailhow the rig uses the wind and turns it into a useful driving force. Gentry who explained correctly, for the first time, the jibmainsail. Sailfish yacht analyzer a velocity prediction program at a fraction of the cost for similar packages. So far fabio fossatis aerohydrodynamics and the performance of sailing yachts.
Sail plans may vary for different wind conditionslight to heavy. Marchaj uses much of the material from my sail magazine articles, and also states that many problems concerning the interference between a mainsail and a jib were clarified by a. Battens on modern sails assist in shaping the after parts of the sail, the cloth is generally stable enough to hold itself fairly well, needing just a bit of help. A fundamental theory of sailing and its application to the design of a hydrofoil sail craft stephen bourn october 2001 abstract this paper presents a general comprehensive but succinct theoretical framework for analysing the forces acting on a sail craft and the resultant sail craft performance. Ocean sampling and surveillance using autonomous sailboats. The crab claw sail is used in many traditional austronesian cultures, as can be seen by the traditional paraw, proa, lakana, and tepukei. The equal length sides are usually longer than the third side, with spars along the long sides the crab claw may also traditionally be constructed with curved spars, giving the edges of the sail along the spars a convex shape, while the leech of the sail is often quite concave to keep it stiff on the. Download pdf aero hydrodynamics and the performance of sailing yachts book full free.
In order to find out where that tradeoff lies, we need to know three things. I know the design process of the regular ship hull where they use the navcad, ghs, rhino and other for different prediction, but never even see a real sail boat. A catamaran cat for short is a multihulled watercraft consisting of two parallel hulls of equal size a catamaran is geometrystabilized, that is, it derives its stability from its wide beam, rather than having a ballasted keel like a monohull. Th velellae sail is a low aspect ratio airfoil with an unusually flat polar plot. It is well known that the trim angle of the head sail, or the distance between head and main sail is very important to the overall performance of the yacht. These battens are tied into the sail with enough compressive force. Several methods are described in this book which can be download free. The performance of any sailing craft depends largely on the power of the available sailhow the rig uses the wind and turns it into a useful driving force. Pdf sails aerodynamics a seatrip around sail shapes. Part 2 aerodynamics of sails, chapter 11 the sail power of various rigs chatterton, edward keble 1912. Sailboat hull cleaned by divers diver missing sail performance.
Snail performance 155 borland ave, auburn, california 95603 rated 4. May 18, 20 i just know the terminology and the physics behind it because i am reading the principles of yacht design by larssson and ca marchaj, sail performance book. In his paper, marchaj showed how unreliable inviscid vortex lattice methods may be as used by milgram 1971 to derive analytical alpha aerodynamic angle of attack or incidence. Accessible and nonmathematical, this major work represents the cuttingedge wisdom on sailboat performance and makes a significant contribution to our. He was the author of sailing theory and practice and approximately 60 other publications. A catamaran is geometrystabilized, that is, it derives its stability from its wide beam, rather than having a ballasted keel like a monohull. From wind tunnel tests which he has conducted, tony marchaj describes how the factors of wind speed, sail area, sail shape, sail setting, the hull, angle of heel, wind gradient and steadiness of the. Aerodynamics, hydrodynamics, sailboats, sails, yachts and yachting.
Catamaran project gutenberg selfpublishing ebooks read. Czeslaw antony marchaj 9 july 1918 21 july 2015, often known in the west as c. Breaking down the complicated concepts of speed, acceleration, torque, fluid mechanics, and surface physics, physics of sailing provides a lively, easily accessible introduction to the basic science underlying the sport of sailing. Numerical and experimental studies of sail aerodynamics. Ships are generally distinguished from boats, based on size, shape, load capacity. It is shown that a requirement for design evaluation is a velocity prediction program vpp which simultaneously accounts for all the effects of design features and their variations. The performance of any sailing craft largely depends on the power of the available sailhow the rig uses the wind and turns it into a useful driving. Yachts and rating formulas aerodynamics of the sail the motion of a yacht wind and water. The sail shapes and performance were measured using sail dynamometer boat fujin. Professor marchaj is also the author of sail performance and seaworthiness, the forgotten. Techniques to maximise sail power 2rev ed by marchaj, c. The wing and airfoil section were designed for equivalent performance to the original sail system, low actuation force, and the ability to precisely control the resulting propulsive system.
Since total sail area was the restriction, a large mainsailsmall jib combination was chosen. Primarily a dragbased locomotory structure, this thin, leaflike sail generates maximum force when oriented at attack angles between 50 and 90. Both squarerigged and foreandaft rigged vessels have been built with a wide range of configurations for single and multiple masts. Performance sails hellingweg 110116, 2583 dx the hague, netherlands rated 4. Marchaj or tony marchaj, was a polishbritish yachtsman and professor whose published scientific studies of the aerodynamics and hydrodynamics of sailing boats have been influential on yacht, sail and rig designers. Generally, the higher the value the faster the boat, provided the boat is stiff enough to handle the larger sail areas.
This is the successor to the authors previous book sailing theory and practice, published over 30 years ago, and takes into account the many developments which have taken place in sail performance since then. Viscous computational fluid dynamics as a relevant. Marchaj published his new book aerohydrodynamics of sailing 14. This volume replaces marchaj s classic sailing theory and pactice, published 25 years ago, and offers new information on, rig design, sail construction and trim, windsail interaction, and. A sail is a tensile structuremade from fabric or other membrane materialsthat uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sailpowered land vehicles. Pdf aero hydrodynamics and the performance of sailing. Open library is an initiative of the internet archive, a 501c3 nonprofit, building a digital library of internet sites and other cultural artifacts in digital form. Computational and experimental study on performance of. It presents revolutionary explanations of wind prediction and boat design, a fundamental rethinking of how to sail a boat fastliterally faster than the wind. A fundamental theory of sailing and its application to the. Based on 25 years of research and olympic coaching, high performance sailing reinvents the strategies of sailboat racing.