Technical & theoretical aspects of RC yacht racing

I'm interested in radio-controlled racing yachts, in particular the International One Metre (IOM) class and the International (now "Classic") A class.  I campaign an Italiko IOM, a Sword "A", and now a 1997 Ten Rater "Puzzle", designed and built by those super-professional folks at SAILSetc.  My Bakers Dozen A, built by Graham in Kevlar to Roger Stollery's design from around 1984, has gone to new home where she is being cared for rather better than I could manage.

This site is aimed at technical and theoretical aspects of RC yacht racing. In particular, it has a number of spreadsheets to download. Although aimed at the IOM, they should be useful for any non-rotating fractional Bermuda sloop rig.

Site news & other interest

Feb 2009:  Seahorse magazine promotional code (see below) is GBN219.

Feb 2009:  I had the chance to photograph a current production Pikanto from Graham Bantock.  These are some pictures and details of the boat.

Feb 2009:  Charlie ran some tests in the wind tunnel.  I hope to show some results later.

Feb 2009:  Reproduced from the Seahorse Web site http://seahorsemagazine.com/2009-February/1.php with permission of the Editor, Andrew Hurst.  Please note that you will receive a substantial discount if you subscribe to Seahorse magazine using the promotional code 'GBN219' in the box at the subscription page at http://www.seahorse.co.uk/shop/subs/ .

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.

To read the remainder of this and many other articles, please purchase your copy of the February 2009 edition of Seahorse International Sailing available at selected newsstands or by calling: + 44 (0) 1590 671899 or by email at: subscriptions@seahorse.co.uk

Individual copies as well as subscriptions can both be purchased online at: www.seahorsemagazine.com

Jan 2009:  An update to my impressions of the RRS 2009 changes following the January 2009 RYA Race Officials Conference.

Dec 2008:  Ken Coles has sent me some comments about his winged rudder.

Site content

My regular additions to the site content have pretty much dwindled away (blame the day job, sorry!), so I thought I'd reorganise the site into better sections to recognise that it is now much more static, and to help newcomers access its content.

The material has been classified into the three major headings of Design, Build, and Race.  Anything not fitting that scheme goes into Other Topics (except for Links and Reports which have a place on the main navigation bar).

Under Design are pages on How a yacht works, How aerofoils work, Where lift comes from, How fins and sails work, Appendage design, Hull design, Sails and rigging design, and The boat as a whole.

Under Build are pages on Hull, Fin & rudder, Bulb, Sails, Rigs & fittings, R/C, and Finishing off.

Under Race are pages on Preparation (Boat speed, Avoiding errors, Strategy), During the regatta, In the race (Boat speed, Avoiding errors, Tactics), and Performance improvement.

Other Topics include pages on International RC racing, Classes, Sailing venues, Event management, Event scoring, Observing, Ancilliary equipment, Bulb calculator, Plans, References & book list, and Terminology.

Commercial stuff

I've developed sticky-backed gauges that can be purchased from SAILSetc.
I publish Larry Robinson's booklet on making model yacht sails using blocks, also available from SAILSetc.
I manufacture a cradle kit, available from SAILSetc.

2009-02-17

©2008 Lester Gilbert