5.5 Metre (keelboat)

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Current Specifications
Class Symbol
Crew 3
LOA about: 10.0 m (32.8 ft)
Beam minimum: 1.90 m (6 ft 3 in)
Draft maximum: 1.35 m (4 ft 5 in)
Hull weight minimum: 1,700 kg (3,700 lb) maximum: 2,000 kg (4,400 lb)
Main & Jib area minimum: 26.5 m2 (285 sq ft) maximum: 20.0 m2 (215 sq ft)
Spinnaker area about: 50.0 m2 (538 sq ft)
Infobox last updated: 21-APR-2010

The International 5.5 Metre Class was created to yield a racing keel boat giving a sailing experience similar to that of the International 6 Metre Class, but at a lower cost.

The main class regulation is a restriction on a single quantity output from a formula involving the boat's rating length L, weight (expressed as a displacement D) and sail area S; the regulation states that the output of this formula must not exceed 5.500 metres. There is considerable scope for variations in design while still meeting this restriction, and as a result each 5.5 metre boat is unique.

If the design parameters of a proposed new boat result in a formula output exceeding 5.5 metres, then one or more of the parameters must be suitably adjusted. Performance data gained from testing models towed in a long water tank (referred to in yacht design as 'tank testing') can suggest optimal combinations of parameters. The 5.5. metre rule is a variant of the International Rule (sailing) that was established already in 1907. The 5.5. is therefore closely related to larger metre boats such as the 6mR, 8mR and the 12mR. The little sister of a 5.5. is the 5 Metre boat.

The President of the International 5.5 Metre Class Organization, Hans Nadorp, has expressed his intention that the 5.5 Metre Class will join the 2012 Vintage Yachting Games. On November 25,2009 the 5.5 Metre Class submitted her joining request for the Vintage Yachting Games Organization.

The Formula

The measurement formula is given in the 2006 International Five Point Five Metre Rating Rules:


5.500 \mbox{ metres} \ge 0.9 \cdot \left( \frac{L \cdot \sqrt[2]{S}} {12 \cdot \sqrt[3]{D}} + \frac{L + \sqrt[2]{S}} {4} \right) </math>


  • <math>L</math> = length for rating
  • <math>S</math> = measured sail area
  • <math>D</math> = displacement in cubic metres

History and Olympic career

File:1952 5.5m race.PNG
5.5-metre class Olympic race in Helsinki 1952. Boats are German Tom Kyle (G I), Gold medalist Complex II (US I) and Danish Jill (D 2).

The 5.5-metre class was a redesign of the 6-metre class by Charles E. Nicholson in 1937. The first boats conforming to the 5.5-metre rule were built in 1949. There had been an earlier attempt to build a cheaper alternative to the Sixes. In 1929 the 5-metre class was established by the French "Union de Societes Nautique Francaise" and the class was accepted in London. It achieved a position as the smallest new international metre class and some hundreds boats were built. Nevertheless the 5 metre never managed to achieve an Olympic status. The 5.5-metre class replaced it quickly and was raced in Olympics for first time in 1952 Summer Olympics in Helsinki. Scandinavian Gold Cup has also been competed with 5.5m boats since 1953. 5.5 metre boats replaced the International 6-metre at the 1956 Olympic Games held in Melbourne, Australia. The 5.5 metre participation in the Olympic sailing events continued at the 1960 Olympic Games and 1964 Olympic Games. During 1960s it however began to draw similar criticism as preceding six-metre class - namely, increasing costs - and the boat lost Olympic status after 1968 Olympic Games, due to excessive design and building costs of one off boats, marking the end of development class keel boats in Olympic regattas. However, the class remained active thereafter and 5.5-metre boats are still very actively raced in 2007 due to an organisational structure which encourages boats of all ages to compete: the class has been divided to Modern, Evolution and Classic subclasses.

External links

de:5.5m IC et:5,5 m ru:5,5-метровый R-класс fi:5.5m sv:5,5 m nl:5.5 Metre