Plan B

International One Metre Racing Yacht

SHOWCASING - PLAN B - A HIGH PERFORMANCE IOM RACING YACHT FOR COMPETITIVE RC SAILING

RADIO CONTROLLED INTERNATIONAL ONE METRE RACING YACHT

Peter Burford, designer and Builder

AUSTRALIA

DESIGN

Plan B is the culmination of more than three years of development, sailing with the very competitive Paradise Radio Yacht Club at Emerald Lakes and at regional events in Queensland, Australia.  We are fortunate with our climate, in being able to sail throughout the year in varied conditions and in a full range of wind strengths.  We Australians enjoy IOM competition at an elite international standard.  It's a demanding field and our yachts must meet the challenge. 

This Plan B design is the third version of the concept, each development requiring a complete set of hull moulds.  Twelve yachts were built and evaluated before Plan B was first offered for sale.  Refinement continues, with Plan B yachts now competing in local, regional, national and international regattas. I receive and act upon input from those at the forefront of competition.  

This photograph shows one prototype, # 128, racing at the Eddie Cowell Regatta, Kawana.

Plan B is a yacht designed to win both single races and protracted events.  It is simple, strong, reliable and easily maintained. Not withstanding, it’s a racing machine.

Behind the clean appearance is a sophistication of thought, design and construction not readily apparent.  I race my boat and know. There are features like an adjustable, ball-ended shaft to centralise the rudder with the Tx trim at 0; wire topping lifts; white foils remain cooler in the sun; neat and accessible wiring; adjustable silicone seal in the rudder bearing; adjustable mainsheet post within the central spine, all lines readily accessible, moulded bow buffer, heat-shrink over all wire terminations, UV resistant silicone O rings, Nyloc limit nuts on the turnbuckles and more.

The easily driven, chined hull has a long, fine entry to elliptical sections in front of the keel and a shallow vee aft into a straight run at the rudder: clean and balanced. The hull shape and foil profile promote responsive steering. This is most apparent when the yacht tacks quickly and easily at low speed and in very strong winds.

It floats bow-high at rest and uses the dynamic lift of the forward sections together with Bernoulli Effect from the aft sections to maintain this attitude downwind at speed.  The fine entry minimises 'tripping' and burying the bow.

When heeled, the hull presents a straight run with narrow cross sections.

The concave, raised fore-deck closely follows the jib-boom and positions the mast ram for effective mast control.

There is a large central hatch, recessed to be flush with the deck, for ventilation and access to the rudder servo, receiver, battery, switch, wiring and corrector weight.  This hatch gives adequate ventilation, without the need to remove the rear deck patch.  The layout is convenient and practical. 

If needed, the flush, deck mounted RMG switch can be circumvented by simply exchanging the installed XT-60 plugs.   The waterproof Hitec HS-646 WP, precisely self-centering rudder servo and the RMG 290 EF winch can be removed and changed through the main hatch, without removing the rear deck patch. 

The rudder shaft, stainless steel tiller and also the winch are readily accessed through the large rear deck opening, covered by the rear deck patch: one flat, easily applied deck patch only, that seldom needs removal. This picture also shows the ‘Rambler’ style rudder with tubercles.

The winch, rudder servo, battery and corrector weight are placed alongside and behind the keel to suit the hull displacement and minimise the overall moment of inertia of the yacht.

Above-deck RMG 32 mm. self-tensioning winch drum and lines give quick and easy access without sheet openings that allow water ingress.  Sheets, winch drum and lines can be adjusted and changed from outside the hull.  The winch drum is shielded with a smooth, rounded cover.  This drum and the Hales deck mounted, ball-raced deck blocks can be readily flushed after racing. The mainsheet runs freely through a wire loop post, to facilitate flick-jibes with the ‘extra-fast’ winch.

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The keel foil is an example of form following function and experience.  The high aspect NACA 0009 section resists stalling when the yacht heels quickly: sheeting in at starts and at sudden gusts.  It enables the yacht to ‘shoot’ a mark. The bow lifts as the yacht heels. The foil has a rectangular profile for minimum surface area with maximum beam and torsional stiffness. 

The ballast is a low drag lamina-flow profile with circular section.  The ballast centre of gravity is at a calculated measurement forward of the foil null point, giving the foil slight wash-out under heeled load. 

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The 'Rambler' rudder profile with tubercles allows an increased angle of incidence before stalling: to improve steering and minimise drag.  The alternative, deeper, conventional blade rudder possibly assists 'parking' the yacht at the starts.  To minimise cavitation from the yacht’s disturbed wake, both rudders are positioned a distance in from the transom.

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Plan B was drawn using engineering CAD, giving accuracy to lines and calculation.

Parameters were calculated and extensively checked before construction.

CAD enabled, for instance, the displacement distribution, wetted surface area and prismatic coefficient to be ascertained and optimised at incremental angles of heel.  The result is a well balanced yacht that can be readily trimmed to 'hands-off' sailing.


Plan B is an attractive yacht, both on and off the water. Good, standard practice; what looks good, is good.

A PERFORMANCE IOM DESIGNED AND BUILT IN AUSTRALIA BY PETER BURFORD
"Everyone needs a Plan B"