Base Plate for Fittings on Yacht Models
Designer
Ben Lexcen
(1936 - 1988)
Datec 1970
Object numberANMS1543[017]
NamePlan
Mediumink on drafting film
Copyright© Ben Lexcen
ClassificationsMaps, charts and plans
Credit LineAustralian National Maritime Museum Collection
DescriptionTank testing base plate, designed by Ben Lexcen (then Bob Miller) during 1974 to use on the scaled tanks testing model of the 12mR Australian challenge yacht SOUTHERN CROSS.
HistoryWater tank-testing scaled models of ship and yacht hulls is now widely adopted 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 manoeuvrable sailing yachts. The process was not fully understood until the American engineering professor and keen yachtsman, Kenneth S.M. Davidson, started carrying out tank testing of boat and yacht hulls in 1931. In 1932, American 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 groundbreaking 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 recognition 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. This was followed in 1966 with the Warwick J. Hood yacht DAME PATTIE and by GRETEL II in 1970. In 1973/74 charismatic entrepreneur Alan Bond, hired Ben Lexcen, (then Bob Miller) to design the 12mR challenge yacht SOUTHERN CROSS (KA-4). Based on a lifelong experience designing, building and racing, fast sailing yachts, Ben Lexcen, was the obvious choice for Alan Bond. A successful small boat designer and international Olympic sailor, Ben Lexcen (previously Bob Miller) had designed many successful ocean racing yachts including: PLUM CRAZY, MERCEDES III, APOLLO, APOLLO II GINKGO, BALLYHOO and ‘CEIL II’. These early yacht designs by Ben Lexcen, (then Bob Miller) were not tank tested. The process is costly and time consuming, as it requires a number of different hull models to be designed, built, and tested in a purpose-built water tank facility. The cost would have been too high for owners of yacht 45-feet long. During the design and development of the 12mR AUSTRALIA he carried out extensive tank testing of scaled models of the hull. He also designed this base plate for fitting to the deck or top of the model so it could be drawing through the water, connected by the plate and flexible joint. 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 (KA-5) in 1977, Ben Lexcen teamed up Johan Valentijn, an experienced Dutch naval architect, who had previously worked for ‘Sparkman & Stephens’ in the US. Ben Lexcen and Johan Valentijn 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. Interestingly, Ben Lexcen and Johan 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 12mR racing yachts, using the Netherlands Ship Model Basin in Wageningen was an obvious choice for Ben Lexcen. He spent a good deal of time designing and re-building the test tank towing carriage, so it pulled the yacht at mast level, where the centre of effort of the sails is located.
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 the Australian yacht AUSTRALIA II (KA-6) designed by Ben Lexcen, skippered by John Bertrand, representing The Royal Perth Yacht Club of Australia, beat the American yacht LIBERTY.SignificanceThe design of the tank towing base plate, would have taken place in 1974 while Ben Lexcen was designing the highly competitive 12mR yacht SOUTHERN CROSS. With the American design team carrying out extensive tank tests and optimising the hull shape to maximum, it would have been vital for the Australian challenge to do the same.
