Proposed modification of afterbody for ship model 5854A
Designer
Ben Lexcen
(1936 - 1988)
Date1975 - 1982
Object numberANMS1543[362]
NamePlan
MediumOriginal on film
DimensionsOverall: 2170 x 650
Copyright© Ben Lexcen
ClassificationsMaps, charts and plans
Credit LineAustralian National Maritime Museum Collection purchased with USA Bicentennial Gift funds
DescriptionAn AUSTRALIA II hull lines plan, indicating significant changes to the aft of the yacht, while Ben Lexcen carried out design and development at the Dutch tank testing facility.
During the four months Ben Lexcen spent at the ‘Netherlands Ship Model Basin’ at Wageningen in 1981, numerous design drawings were produced and many changes made. It was a period of ‘on-going design improvements’, during months of work at the tank testing facility, which are clearly visible in the work. Even small changes to the underwater hull shape will influence the overall weight of the yacht and hydrodynamics acting on the hull. The result was the revolutionary designed winning yacht AUSTALIA II. HistoryWater tank-testing scaled models of ship and yacht hulls is now widely used around the world in order to optimise the hull shape to suite their working environment and purpose. Modern equipment and advanced computer software, all help to produce fuel efficient hulls and propellers, as well as fast and maneuverable sailing yachts. The process was not fully understood until the American engineering professor and keen yachtsman, Kenneth S.M. Davidson, starting carrying out tank testing of boat and yacht hulls in 1931. In 1932, yacht designer Olin Stephens, gave him a six-foot-long model of the yacht NATKA which he wanted to use as previous water tank testing had proved unreliable. His ground breaking work proved its worth following the 1936 tanks tests of several models by yacht designers Olin Stephens and Starling Burgess, who jointly designed the J-Class yacht RANGER. The 1937 America’s Cup race was held Newport, Rhode Island from July 31st to August 5th where RANGER, with Ken Davidson as navigator, beat the British yacht ENDEVOUR II owned by Sir Thomas Sopwith. The success of this race brought reignition to Ken Davidson and clearly indicated the advantage of tank testing models.
Australia’s quest for the coveted Americas Cup began in 1962 with the Alan Payne designed GRETEL. In 1973/74 entrepreneur Alan Bond, hired Ben Lexcen, (then Bob Miller) to design the challenge yacht SOUTHERN CROSS (KA-4). Based on a lifelong experience designing, building and racing, fast sailing yachts, Lexcen, was the obvious choice for Alan Bond. A successful small boat designer and international Olympic sailor, he 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 Lexcen went on to design and build AUSTRALIA (KA-5) for the 1977 and 1980 races. For the design of AUSTRALIA in 1977, he teamed up with Johan Valentijn, an experienced Dutch naval architect, who had previously worked for ‘Sparkman & Stephens’ in the US. The designers spent seven months in 1976 testing 1/9th scale models of AUSTRALIA 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). This hull, half frame ‘lines plan’ of AUSTRALIA II, is an example of the changes made, even during the later stage of the design program. The America’s Cup trophy was held by the New York Yacht Club, which successfully defended twenty-four challenges for 132 years. This all changed in 1983, when AUSTRALIA II, skippered by John Bertrand, representing The Royal Perth Yacht Club of Australia, beat the American yacht LIBERTY.SignificanceBy reducing the displacement by 0.5m3, Ben Lexcen was able to make the yacht lighter by 513 kilograms. Overall, this may not appear much, but combined with other design changes, and together with the revolutionary ballast keel, would all make the yacht faster. The final weight of AUSTRALIA II was 21.8 tons compared to the 24.35 tons of the rival America yacht, LIBERTY.
