Instructive

World champion designer and skipper Graham Bantock guides Dobbs Davis through the nuances of International One Metre development

There are no box rule classes in sailing that boast more diversity in design than the International One Metre (IOM) class. Since the IOM was introduced in the late 1980s dozens of designs have been tried and tested throughout large and highly competitive fleets in Europe and Australasia, with no one variety evolving to dominate. Why has a unique solution not been found to these intriguing radio-controlled yachts? The answer lies in the quasi-tolerant nature of the box rule, the diversity of regatta venues and the relentless pace of development in hull and appendage shapes, albeit within fairly strict rule parameters.

The IOM’s genesis in 1988 started with the goal of creating a class that would be simpler, smaller and cheaper than the Marblehead and other larger boats, with several key features:

• Three one-design rigs, each with tightly controlled sail sizes and profile.
• A sound method for determining draft restriction with a minimum and maximum value.
• Alloy or wood spars only.
• Glass or wood hulls only.
• Two channels of radio control (RC) only.
• A maximum weight for the ballast plus fin and minimum for the complete yacht.

‘The class was for people who wanted a yacht that would be restricted to many of the same basic parameters as others in the fleet,’ explains Graham Bantock. ‘Unlike some of our other classes, this fleet was not to be a battleground for highly skilled builders with better technical solutions.’ No one would know this better than Bantock, whose shop has produced amazingly detailed technical solutions to every component part of RC yachts for nearly two decades.

But as the IOM grew and developed in the early 1990s clever attempts to poke at the limits of the rule were repeatedly stymied by the class hierarchy, whose rulings generally fell in favour of keeping to the basic principles. This became particularly important as the fleet increased past 1,000 boats in 1994, when significant changes would risk rendering many boats obsolete. Nonetheless, trickle-down innovation from the less restricted Marblehead found its way into the IOMs, including, but not limited to, hull shapes and appendage types.

Bantock’s ongoing analysis has generated many interesting trends in wetted surface, righting arm, and stability, and waterline length. Since it is regattas and not tanks or CFD simulations that are the true proving grounds for IOM design, Bantock’s own timeline serves as a useful synopsis of design evolution.

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