Model 5854 and Model 5854A with Keel II Lambda = 3

Designer Ben Lexcen (1936 - 1988)

Date1975 - 1982

Object numberANMS1543[360]

NamePlan

MediumCopy on film

DimensionsOverall: 950 x 730

ClassificationsMaps, charts and plans

Credit LineAustralian National Maritime Museum Collection purchased with USA Bicentennial Gift funds

Terms

DescriptionA half drawing of the ‘hull lines plan’, made during the design, development and tank testing, of the hull and ballast keel of ‘AUSTRALIA II and CHALLENGE 12, by Ben Lexcen and the Dutch test tank team, in 1981. It is likely photo-copied in two halves in order to provide more detail and is an example of the changes made, even during the later stage of the design program. HistoryThe first America’s Cup yacht to be tank tested was the British J-Class SHAMROCK II, designed by George Watson in 1900. Owned by Sir Thomas Lipton, Watson, a naval architect, spent nine months extensively tank-testing nine different models in the 300-metre-long Denny facility. The result of this work was a greatly improved hull with a finer underwater shape in the bow area. The 11th America’s Cup challenge took place in New York harbour on September 26th 1901, between the British challenger SHAMROCK II with captain Sycamore at the helm, and the America yacht COLUMBIA steered by captain Barr. In the final race SHAMROCK II crossed the finishing line two seconds ahead of COLUMBIA but lost by 42 seconds on handicap. The method, technology, and deeper understanding, of tank testing yacht hulls did not improve until Davison’s work on towing tank test models in 1936. Australia’s quest for the coveted Americas Cup began in 1962 with the Alan Payne designed GRETEL. This was followed in 1966 with the Warwick Hood yacht DAME PATTIE and by GRETEL II in 1970. In 1973/74 entrepreneur Alan Bond, hired Ben Lexcen, (then Bob Miller) to design the 12 metre challenge yacht SOUTHERN CROSS (KA-4). Based on a lifelong experience designing, building and racing, fast sailing yachts, Lexcen, was the obvious choice for Bond. A successful small boat designer and international Olympic sailor, Lexcen had designed many successful ocean racing yachts including: PLUM CRAZY, MERCEDES III, APOLLO, APOLLO II, GINKGO, BALLYHOO and CEIL II. The 1974 Australian challenge was not successful, but he went on to design and build AUSTRALIA (KA-5) for the 1977 and 1980 races. For the design of AUSTRALIA in 1977, Lexcen teamed up Johan Valentijn, an experienced Dutch naval architect, who had previously worked for ‘Sparkman & Stephens’ in the US. The designers worked together on a number of yachts, including the 45-foot IOR yacht GUIA V in 1976, for the experienced Italian ocean-racing yachtsman, Giorgio Falck. Lexcen and Valentijn spent seven months in 1976 testing 1/9th scale models of AUSTRALIA (KA-5) at the University of Delft test tank in the Netherlands. This period of on-site design and tank-testing scaled models in the water, proved vital for future design work on AUSTRALIA II (KA-6). With considerable experience in tank testing 12 metre racing yachts, using the Netherlands Ship Model Basin in Wageningen was an obvious choice for Lexcen. Many design drawings were produced, and scaled models built and tested. A computer analysis was made at each design change, using tank testing software and collaboration with the ‘National Aerospace Laboratories of the Netherlands’ (NLR). SignificanceA good example of the ongoing design work and changes made to the hull shape of AUSTRALIA II and CHALLENGE 12 while tank-testing in 1981. The drawing indicates a significant design change was proposed by Ben Lexcen in order to reduce the displacement and improve the hydrostatics to the afterbody of the yacht AUSTRALIA II.

The on-going design improvements, during months of work at the tank testing facility, are clearly visible in the work. Even the smallest change of the underwater hull shape will influence the way water will flow past it, or effect the overall weight of the yacht.