Clockwise from top left: Olin Stephens and Intrepid got the plaudits in 1967 but in 1910 the ‘junior’ 12 Metre Alliance was carrying all before her with a similar separate keel and spade rudder configuration; how many novel features can you get in one boat, bearing in mind this fabulous-looking 21ft Manfred Currey design was built in 1927 – the hull can best be described as Ultim trimaran meets AC75, then there is the balanced rig, the tripod ‘mast’… plus what you can’t see is a gybing centreboard (5° each way) controlled by a spiral crank with sliding plates to seal the slot; the Tucker-designed Duck Quacky 2 was 36in champion in 1950 and 1952; in 1978 the Marblehead Pickaxe introduced the modern swing rig to the class; not a scow but pretty blunt nonetheless, Alex Austin’s 36in design Xasperachun was (finally) national champion in 1977; while in 1968 Roger Stollery introduced modern double-luff sails on his champion Ten Rater Mr Rusty – today double-luff sails have become a dominant feature of model yacht racing… just in time for AC36


water so that a central-ballast keel will come very close to the water surface at its junction with the hull which, due mainly to the formation of a standing wave (for a fuller explanation see Seahorse issues 206 and 207), makes it very inefficient; it might even break the water surface which makes it even less efficient. It could, of course have twin fins,


angled such that one of them comes out of the water when heeled, but the wetted area goes up when there is not enough breeze to get the windward fin out of the water. The beauty of bilge boards (as used on Ameri- can lake scows) is that they remain fully immersed in deeper water under the bilge which when heeled is the bottom of the boat and the one not in use is retracted and therefore produces no drag. But we digress. We quickly found in


models that the Achilles’ heel of the concept was plugging to windward in a chop. Typically, in vane sailing, most of which


takes place on windward-leeward courses, it would lose out at the beginning of the beat in the rough water at the leeward end of the lake but would catch up and very often pass the other boat at the calmer windward end of the lake.


56 SEAHORSE But it was defiantly faster downwind. I


understand that this is still roughly the profile at full size, but because in offshore racing there is a random chance that 75 per cent of the race is offwind and there is thus often little windward work, if any, it can be a winning combination. Plus the races at which these boats excel, most obviously the Mini Transat itself, have courses that are predetermined long in advance and designs are tailored to suit. It is interesting that model yachting was


once again way ahead of full-scale design. This is a recurring story. For instance, although not new – it was used in the late 1800s in the raters of the time – the concept of the separate fin and rudder reappeared in model yachting as early as 1910 in the model 12 Metre class. By the mid-1920s it was in almost universal use in models of all sizes, but it took until the mid-1960s to reappear in full-sized yachts. Bearing in mind that the America’s Cup should be at the leading edge of design


‘The best prophet of the future is the past’ – Lord Byron


technology, it is somewhat curious that it took until the design of Olin Stephen’s Intrepid in 1967 for the concept to appear in the full-sized 12 Metre and America’s Cup world. When it did finally arrive it was a large step forward in performance that should have been available many years earlier. Indeed, had it been employed earlier it may well have altered the course of America’s Cup history. There are other well-documented


examples. The bulb keel, again popular in the late 1800s in the raters of the time, went out of fashion in both the full-sized and model worlds. However, it reappeared in models in the late 1950s and early 1960s, the main proponents being myself and Roger Stollery. At a stroke it made possible a much lighter, less draggy boat for the same righting moment and that is a compelling recipe for speed. And so it was, and in a very short time,


that the bulb keel was back in almost uni- versal use in practically every model yacht class. By contrast it took till the 1980s to become general practice at full size. A note of caution, however. A bulb


keel is draggy so it is not all gain. That extra drag has to be negated by a larger


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