|Crew||2 (single trapeze)|
|LOA||5,050 mm (199 in)|
|Beam||1,880 mm (74 in)|
|Draft||1,450 mm (57 in)|
|Hull weight||127.4 kg (281 lb)|
|Main & Jib area||14 m2 (150 sq ft)|
|Spinnaker area||26 m2 (280 sq ft)|
The International 505 is a one-design high-performance two-person monohull planing centerboard dinghy, with spinnaker, utilizing a trapeze for the crew. Successful teams come in many combinations, including all female, all male, mixed, and child/adult or child/teen. While it is high performance and (as is true of any dinghy) very demanding in a blow, the 5o5 has extraordinary good handling and is actually easier to control than many smaller trapeze boats.
The genesis of the class began in 1953 with the creation of the 'Coronet' dinghy designed by John Westell. This sailboat competed for the two-person performance dinghy classification for the Olympics at the International Yacht Racing Union (IYRU) trials of 1953 held at La Baule, France. In 1954, the Caneton Association of France requested John Westell to make significant changes to the design to suit their needs. This reduced the overall length, weight and reduced the sail area to become the 505, so named for its length of 5.05 meters. The class achieved international status with the IYRU in 1955.
The class is a popular international class and is actively raced in 18 countries around the world. World championships are held every year at rotating by continent locations around the world, and attract in excess of 100 boats on the start line. At the 2005 world championships held in Warnemünde, Germany there were 171 boats. The 2009 Worlds were held in San Francisco.
The design of the boat's hull shape and sailplan are tightly controlled, while the spars, foils and disposition of the rigging is open. This allows the boats to be set up to the needs of the sailor, rather than controls established by the class association, resulting in a high level of adaptability to sailing styles. There are a number of successful sail/layout combinations. This freedom to rig as you please allows for a remarkably wide range of crew weights and configurations to be competitive in big regattas. It also fosters a greater degree of seamanship and boat wisdom, as teams learn to understand and become proactive in issues such as proper sheeting lead position, standing rigging attachment, secure equipment foundations and all the other aspects of rigging and layout which are so important to the well-rounded and knowledgeable sailor.
As of 2005, there are 14 known builders throughout the world. Construction materials range from fiberglass/polyester to carbon fiber, with just about every conceivable construction material used at one time or another within the class. Modern boats with modern materials are capable of remaining competitive at the international level for ten years or more. As of 2009, over 9000 505s had been built since 1954.
Various modifications to the accepted design outside of the class rules have been conducted at different points in history. Such modifications have included setting up a double trapeze system, installation of a bowsprit, and inclusion of an asymmetric spinnaker. The most recent of these modifications have been made by Mike Arnold of the Deben Yacht Club in Woodbridge, UK, who has been experimenting with a 505 hull and rig modified to have a higher boom (i.e. a cut down main) and an asymmetric spinnaker that flies from a movable bowsprit. This may be the genesis of a new class known as the "Alto". However those who know and love the 5o5 eschew the bowsprit as the symmetrical chute and traditional pole give better performance on the typical windward leeward courses run today.
Other classes of dinghy