Frame and Construction Elements used as a disinformation campaign to fool competitors
Designer
Ben Lexcen
(1936 - 1988)
DateJune 1981
Object numberANMS1543[329]
NamePlan
MediumPencil on tracing paper
DimensionsOverall: 1370 x 760
Copyright© Ben Lexcen
ClassificationsMaps, charts and plans
Credit LineAustralian National Maritime Museum Collection purchased with USA Bicentennial Gift funds
DescriptionAn unusual hull ‘web-frame construction’ drawing, dated June 1981, for a glass-fibre built, America’s Cup challenge yacht for 1983.
HistoryThe 12-Metre International class, best known as the yachts designed and built especially for the America’s Cup races, were much smaller than the earlier J-Class yachts used up to 1937. After a break of twenty-one years, the America’s Cup series was re-started in 1958, using a smaller racing yacht. The 12mR International Class yachts are all between 60 and 70-feet overall, in comparison to the J-Class which were built up to 135-feet in length. Both classes were based on a mathematical formula or rule. The 12mR International Class yachts were built and raced from 1958 to 1987 when it was replaced by the International Americas Cup Class in 1992.
During his career, Ben Lexcen designed seven Australian "America’s Cup" challenge yachts: SOUTHERN CROSS 1974, AUSTRALIA 1977, re-designed AUSTRALIA 1980, AUSTRALIA II 1983, CHALLENGE XII 1983, SOUTH AUSTRALIA 1985, AUSTRALIA III 1985 and AUSTRALIA IV in 1986. All of these yachts were built in marine grade aluminium. Following the success of AUSTRALIA II in winning the 1983 America’s Cup, Ben Lexcen achieved international recognition as an innovative yacht designer and naval architect. Despite his work on these prestigious yachts, he also produced designs for many offshore racing yachts, as well as smaller 6mR racing yachts and dinghies. Later, in 1986, a ‘quarter scale’ version of AUSTRALIA II called Baby Twelve KA-6 was designed and built. This was a single crew, glass fibre production boat, of 4.80 meters overall, a beam of 0.91 meters, and measured 1.3 m from the bottom of the keel to the deck.
The design drawing, dated June 1981 with No. 4a on it, shows ten hull and deck web-frames, made in glass reinforced plastic (GRP). The work suggests it is for one of the 1983 America’s Cup challenge yachts, but this is unlikely to be the case, as Ben Lexcen did not design any 12mR yachts in glass fibre. The numbering of the web-frames shown on the drawing is from the stern to the bow, but with all his 12mR yachts they started at the bow and worked back to the stern. Also, the dimensions shown on the drawing are for a much smaller boat. So, with so much international prestige involved with the design, build and racing of 12mR yachts, it is likely this work was used to confuse or mislead the competition. The design and development of the hull, rudder, ballast keel and the mast on AUSTRALIA II and CHALLENGE XII in 1981 and 1982 were all kept very secret. When the hull of AUSTRALIA II was taken by road from the builder to the launch site, part of the hull and all of the ballast keel was covered. This was also the case later in the USA, when all the competing 12mR yachts were launched. The America team even put divers in the water near AUSTRALIA II to try and get information about the inverted winged ballast keel and the hull shape. All to no avail, and they were stopped by the Australia team who also had divers down!SignificanceThe design drawing is a ‘mystery work’ from the Ben Lexcen design office, showing the hull and deck web-frames for a small GRP sailing yacht. The work, dated June 1981, suggests it is for one of the 1983 America’s Cup Challengers, but the dimensions supplied do not match any 12mR International yacht. Potentially this plan was drafted as part of a disinformation campaign to fool racing competitors. 
