Sketch of keel plan for CHALLENGE XII
Designer
Ben Lexcen
(1936 - 1988)
Date1936 -1988
Object numberANMS1543[363]
NamePlan
MediumCopy on film
DimensionsOverall: 650 x 300
Copyright© Ben Lexcen
ClassificationsMaps, charts and plans
Credit LineAustralian National Maritime Museum Collection purchased with USA Bicentennial Gift funds
DescriptionA Ben Lexcen working drawing, with hand written notes and calculations, for the ballast keel of the Australian challenge yacht CHALLENGE 12. Designed in 1981 and built by ‘Steve E. Ward & Co.’ in Perth, Western Australia in 1982.
During the four months Lexcen spent at the ‘Netherlands Ship Model Basin’ at Wageningen in 1981, numerous design drawings and test model were produced and many changes made to both AUSTRALIA II and for CHALLENGE 12. It was a period of ‘on-going’ design ideas, changes and improvements, at the tank testing facility. Lexcen’s ideas, notes and calculations at the time are clearly visible on this work. HistoryIt is extremely unusual for a yacht designer to be commissioned by one client to design two America’s Cup challenge boats at the same time for the same race. Yet Alan Bond, chairman of the Australian syndicate, chose Ben Lexcen to design two 12 metre yachts for the 1983 challenge. Based on a lifelong experience designing, building and racing, fast sailing yachts, Ben Lexcen, was the obvious choice for Alan Bond and the Australian syndicate.
A successful yacht designer and international Olympic sailor, Lexcen (previously Bob Miller) had designed many successful ocean racing yachts in the 1960’s and 70’s. With considerable experience previous tank-testing of 12 metre racing yachts, Lexcen was keen to use the Netherlands Ship Model Basin in Wageningen as it had the right size to test his 1/3rd. scale models. During early 1981 many design drawings were produced, and scale models built and tested. This drawing of the ballast keel, with the distinctive ‘bulb shape’ and pointed lower edge is for CHALLENGE XII (KA-10) which later proved to be a fast boat very much liked by the Australian crew. A computer analysis was made at each design change, using tank testing software and collaboration with the ‘National Aerospace Laboratories of the Netherlands’ (NLR). CHALLENGE XII and AUSTRALIA II were built by ‘Steve E. Ward & Co.’ at Cottesloe near Perth, Western Australia. Both yachts had identical deck layouts, masts and rigging, but a vastly different underwater shape. The displaced weight of CHALLENGE 12 at 23.8 tons is significantly more than AUSTRALIA II. The yacht also had a larger ‘bustle’ aft and more volume in the forefoot. The ballast keel was conventional in plan-view but sported a bulbous shape in section view, lowering the centre of gravity.
Alan Bond decided to use AUSTRALIA II for the 1983 Americas Cup challenge and CHALLENGE XII was sold to the 'CHALLENGE 12’ Syndicate’ in 1983, later shipped to Newport, Rhode Island in the US for the race trials. CHALLENGE 12 was not successful in the trial races at Newport, Rhode Island, in 1983 but despite this, the yacht was used by several future challenge syndicates in France and Italy. In 1996 CHALLENGE 12 underwent an extensive three-year refit and raced again at the St. Tropez Rolex Cup in 1999. In 2019 CHALLENGE 12 won the the Modern Division of the 2019 12 Metre World Championships help at Newport.SignificanceThe ballast keel on CHALLENGE 12 is very different to the inverted wing keel on AUSTRALIA II but both yachts were designed by Ben Lexcen at the same time in 1981. The hand written notes, added to an otherwise ‘lifeless photo-copy’, are off particular interest as it provides an insight into the ideas and thoughts of the designer at the time. 
