(Really) high-speed sailing – Part II

Bob Dill and Phil Rothrock look at the story of The Hundred Knot Sailboat

Top sailing speeds have increased significantly since Bernard Smith laid out his vision of the ultimate sailing craft in his book The 40-Knot Sailboat in 1963. While speeds on the water are closing in on 50kt this is well short of the speeds seen for many years now on ice and dirt. Racing yachts on both ice and dry lake beds regularly top 65kt, while specialised speed machines have achieved 101kt and look poised to go faster still in the near future. This article reviews the top speed performance of the fastest racing yachts, dispels a couple of myths... and describes what it takes to sail at over 100kt.

Properties of ice and dirt
The runners or ‘skates’ used on iceboats have a low speed coefficient of friction of less than 1%. The runner creates a 1mm groove in the ice and experiences zero leeway until it gets near to its lateral traction limit. On dirt the low speed drag is around 2% and there is typically around 5 degrees leeway when the boat is powered up. At low speeds the coefficient of lateral traction is a little under 1.0 on ice and about 0.7 on dirt and salt. Traction decreases with increasing boat speed.

To read the remainder of this and many other articles, please purchase your copy of the May 2008 edition of Seahorse International Sailing available at selected newsstands or by calling: + 44 (0) 1590 671899 or by email at: subscriptions@seahorse.co.uk

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Below: The Iron Duck at speed on Ivanpah Dry Lake in Nevada where in 1999 she set the current world land sailing record of 116.7mph. Designed and built by Bob Dill, the 840kg Iron Duck is steel framed and clad in foam/grp fairings and powered by a solid wing