There are two primary methods of competition in sailboat racing: One-Design and handicap (see: Portsmouth Yardstick,[1] PHRF[2] and LYS (Leading Yard Stick)). One-design refers to a racing class that consists of just one model or design of sailboat. In one-design racing, the first boat to finish wins the race. This is contrasted with handicap racing,[3] where time is added or subtracted from the finishing times based on design factors and mathematical formulas to determine the winner.[4]

In between One-Design and handicap racing, a number of other approaches exist. One-Design can be contrasted with a development class, the classic example being the America’s Cup 12-metre class, or to the Box Rule[5] used, for example, in the TP 52 class.[6]

A further category, the formula based class setup, is sometimes confused with one-design. The Mini Transat 6.50, the Volvo Open 70 monohull, the large ORMA trimaran, and the Formula 18 racing beach catamaran are the exponents of the formula approach. Class-legal boats race each other without any handicap calculations in both setups. However, under one-design the boats are virtually identical except in details, while the Formula setup allows the boats to differ much more in design while keeping a few important specifications the same. As a result, the identifier “One-Design” has been used more and more exclusively to denote a class that races only identical boats.[citation needed]

Having a rigid one-design specification keeps design experimentation to a minimum and reduces cost of ownership. The popularity of one-design increased in the 1970s with the introduction of laminate construction using fibre-reinforced plastic (FRP) and mold building technology. This process allowed the mass production of identical hulls of virtually any size at a lower price.[citation needed]

The one-design design idea was created by Thomas Middleton of the Shankill Corinthian Club located 10 miles (16 km) south of Dublin, Ireland in 1887. He proposed a class of double ended open dinghies of simple clincher construction in pine with a lifting boiler plate capable of being lifted. The boat was called The Water Wag. The idea was quickly adopted by sailors in Ireland, England, India and South America. The Water Wag Club still thrives in Dun Laoghaire, Co. Dublin.[7]

The Solent One Design Class was one of the earliest O.D. classes formed after discussions took place in 1893 and subsequent years. It quickly became popular, and was patronised by some of the most energetic and best known yacht owners in the Solent, Portsmouth and Southampton waters including Sir Philip Hunloke, the King’s yachtmaster. Formed under the auspices of the Solent Sailing Club, the class was adopted by the Royal Yacht Squadron and the Island Sailing Club in 1895. The dimensions of the boats were length overall, 33 ft 3 in; Waterline length, 25 ft; Beam, 7 ft 9 in; Draft, 5 ft; Sail area, 750 sq ft.; Displacement, 5 tons with 2 tons 13 cwt. of lead in the keel. Cutter rig with 6 ft bowsprit. Designed by H.W. White, ten were built in 1895/6 by Messrs. White Brothers of Itchen Ferry, Southampton and another twelve were built in the following year. The class enjoyed ten years of keen racing but the Metre Rule, which was introduced in 1907 effectively killed the class. The only boat still afloat is Rosenn, formally Eilun, sail number 6. Now, fully restored, she has been identified as meriting inclusion in the National Register of Historic Vessels of the United Kingdom. She is kept in Lymington where she is still racing and winning on the Solent.[8]

As a general rule, the tolerances are strictest in smaller boats like dinghy classes and small keelboats. In some cases the tolerances are specified in a confidential Building Specification and often everything is designed and produced at the same factory or a very few factories. Examples are the LaserMelges 24, and several small keelboats designed by Nathanael Greene Herreshoff, such as the 12½. In others the specification is published but the boats may only be produced by licensed manufacturers with usually only one builder in any country or region. Examples are the Olympic Finn and 470 but in both these classes a single manufacturer has succeeded in building faster boats than all other manufacturers. In yet others, for example the Optimist anyone may manufacture but tight controls of measurement result in strict one-design.[9]

In medium- to large-sized boat classes, One-Design would refer to conformance to a standard specification, with the possibility of alterations being allowed as long as they remained within certain tolerances. Examples of this are the DragonJ/24Santana 20Tartan 10EtchellsJ105Schock 35C&C Mega 30 One Design[10] and the Farr 40. After the hull length overall (LOA) exceeds 27 feet (8.2 m), people generally refer to the boat as an offshore one-design boat or yacht.[citation needed]

In other classes, the one-design class may have organized around an existing fleet of similar boats that traditionally existed together often for commercial purposes[citation needed]such as sailing canoes, dhows, and skipjacks, or boats that developed a common hull form over the years (such as A-Scows).[11]

In contrast to ‘one-design’, other sailboats race under a variety of handicapping rules and formulas developed to allow different type boats to compete against one another. Formula rules include the Square Metre Rule, the Ton class, the Universal Rule, and the Metre Rule. Handicap rules include Portsmouth YardstickPHRFIORIMSIRC, Americap[12] and LYS.