Lines plan of 7202 used for hull weight calculation
Designer
Ben Lexcen
(1936 - 1988)
Date1972
Object numberANMS1543[081]
NamePlan
MediumPencil on drafting film
Dimensions770 x 1300
Copyright© Ben Lexcen
ClassificationsMaps, charts and plans
Credit LineAustralian National Maritime Museum Collection purchased with USA Bicentennial Gift funds
DescriptionA Ben Lexcen (formally Bob Miller) hull ‘Body Plan’, with hand-written calculations, for a proposed scale model of the 12mR America Cup challenge yacht SOUTHERN CROSS (K-4) designed in 1972 and 1973 for the 1974 Americas Cup races.
HistoryInitial design work for the Alan Bonds first 12mR America’s cup challenge yacht SOUTHERN CROSS (K-4), started in late 1972 and continued through 1973. During the early stages of the design project, Ben Lexcen (formally Bob Miller) will have studied and gathered as much information about other International 12mR yachts as possible. He will have obtained copies of previous 12mR yachts and used these to make his own design, based on his success designing winning offshore racing yachts.
By early 1973 several hull designs were proposed, and scale models built and tested, so as to study the resistance, wave making and stability qualities of each. Model 7202 was one such model. This was important work as the America’s cup challenge yacht SOUTHERN CROSS represented Australia, its yacht design, build, management and above all the skill and seamanship of the crew. The defending American design team had a large budget, as well as the best materials and resources to draw on, so they too carried-out extensive design work and tank testing. Several scaled models of SOUTHERN CROSS hull and ballast keel were built, varying from 1.41 metre to 1.51 metre in length overall. When tank testing, an allowance is made for the actual weight, so they can be tested in the water to check the designed hydrostatics, pounds per inch of emission, hull resistance, wave making, overall displacement and so forth. These tests take place in large, purpose-built water tanks, which allow the vessel to be towed though the water and information gathered to fully optimise the hull shape.
A self-taught naval architect, yacht designer and accomplished yachtsman, Ben Lexcen was born Robert Clyde Miller, on March 19th. 1936 at Boggabri, in New South Wales, Australia. He left school at fourteen, after only five years formal education, to become an apprentice machinist at the New South Wales locomotive works. In 1952, at the age of 16, Ben Lexcen (then Bob Miller) designed and built his first sailing boat ‘THE COMET’ with his friend William Bennett. He soon began to make a name for himself at local sailing competitions. In 1960 he entered his boat ‘TAIPAN’ in the 18-Footer World Championships, and later winning the World Championship in 1961 with his design, the 18-foot skiff ‘VENOM’. In 1962, together with his friend Craig Whitworth, he set up the ‘Miller & Whitworth’ sail making business in Sydney, while continuing to design sailing dinghies. An accomplished sailor, then Bob Miller represented Australia in the Soling class at the 1972 at the Olympic Games at Munich, West Germany.
Bob Miller (later Ben Lexcen) soon became known for his fast, lightweight, racing yachts which included, PLUM CRAZY, MERCEDES III, APOLLO, APOLLO II, GINKGO, BALLYHOO and CEIL III. These early yacht designs were not tank tested, as the process is both costly and time consuming. It requires several different hull models to be designed, built, and tested in a purpose-built water tank facility. The costs involved would have been too high, and considered unnecessary, for owners of yachts of around 45-feet long.
Alan Bond and Bob Miller (later Ben Lexcen) were together at Newport, Rhode Island in 1970, preparing for the 636-mile Newport to Bermuda race. Together with the Australian team, they were preparing Alan Bond’s racing yacht ‘POLLO at ‘Bob Direcktor’s Shipyard, at Mamaroneck, New York. While visiting a boatyard together at City Island, New York, Alan Bond spotted a large sailing yacht alongside, which unusually, had all the deck winches and crew positioned below deck. Alan Bond wanted a closer look so wondered down the pontoon to study the boat and layout but one of the crew took offence and shouted for him to go away. This did not go well, and when asked what type of boat it was anyway, was told it was the America Cup yacht ‘VALIANT’. Still mystified, Bob Miller explained what the America Cup was and about the yachts involved. To which Alan Bond told Bob Miller. ‘You design me one of those 12-metre boats, and we’ll come back here and win their bloody America’s Cup.’
With an overall length of 20.45 metres (67.09 feet) and beam of 3.71 metre (12.17 feet), SOUTHERN CROSS (KA-4) was built of aluminium at Terry Hills, Sydney by ‘Halvorsen Morson and Gowland’ of Mona Vale and launched in 1974. Following sea trials and crew training alongside the previous challenge yacht ‘GRETEL II’, SOUTHERN CROSS was shipped to the USA for the American elimination trials. The American 12mR yachts; INTREPID, MARINER, VALIANT and COURAGEOUS were all trying to be the defending yacht for the cup challenge. Skippered by talented Australian Jim Hardy, SOUTHERN CROSS did her best, but ultimately lost to COURAGEOUS skippered by Ted Hood. SOUTHERN CROSS was not successful in winning the America Cup in 1974 but in 1983 Alan bond returned to Newport with the Ben Lexcen designed AUSTRALIA II. Captained by John Bertrand, the yacht beat the American yacht LIBERTY and Australia finally won the America’s Cup.
SignificanceDuring the design of the 67-foot SOUTHERN CROSS, the first 12mR America’s Cup challenge yacht for Alan Bond, Ben Lexcen (then Bob Miller) designed and built several scaled models of the hull, to test the shapes in a water tank facility. This work shows the hull in plan and profile view of model 7202, and the 47-hull frames which were made to build it.
