Aussie IRC Offshore Cruiser/Racer
Winning IRC designs come in all shapes and sizes. Optimizing a design to the IRC rule simply means getting the balance of essential parameters to reflect the proposed type of racing, wind conditions, competition and owner's requirements. Without this, no amount of “features” will make it a race winning design. The R39 was designed specifically for the West Australian coast with high righting moment, moderate upwind rig and big spinnakers.
The hull form is very clean, moderate displacement with a high righting moment deep bulb keel. Water ballast is included simply to take the place of five crew on the rail – a plus for racing and cruising. Both the foils are moderate aspect ratio, stall resistant profiles to give the boat lots of feel and a wide optimum speed groove. Auxiliary propulsion is from a light weight Lombardini 30 hp diesel engine driving through a Boatspeed retracting propeller transmission system. This gives the advantage of a fixed three-bladed propeller under power whilst leaving a completely flush hull surface when racing.
Not being a limitless budget project, the hull, deck and internals are wet layup epoxy and E-glass over Corecell foam with unidirectional carbon cappings in select high load areas.
The cockpit combines angled coamings, very comfortable back rests and long seats with a large open area aft – perfect for twilighting. The cockpit continues forward into the coachroof, providing a safe and comfortable area to operate the halyard/spinnaker sheet winches. The tacking pedestal Vanguard Steering System frees space in the cockpit and allows easy access forward and aft of the helm position. Not only lighter than a conventional twin wheel system, it allows increased steering sensibility by eliminating the inertia of the second, non-steering wheel. There are lazarette lockers aft and a liferaft locker forward, also giving access the lifting propeller transmission system.
The carbon rig was supplied by Applied Composites in Melbourne. It has twin swept back spreaders with composite shroud chain plates on the sheer. It is a work of art to behold and easily tuned with help of hydraulic mast jack. The boat is set up for both symmetric and asymmetric spinnakers. Given the predominantly offshore role envisaged the default arrangement is masthead asymmetric reaching and running spinnakers carried on the fixed bowsprit.
The simple and open interior features comfortable saloon settees with backrests which hinge up to form pilot berths. The interior sleeps ten in port and four crew can sleep comfortably to windward whilst racing. There are large galley areas port and starboard amidships with ample fridge and ice-box volumes. The navigation area is located amidships under the companionway bridge deck with a hatch for communication with the helmsman.
Many opponents of the IRC rule will admit that it is able to produce very wholesome designs – high righting moment, robust, dual purpose cruiser racers. This is one of them. The design brief was for efficient, not funky.
R39 Specifications: LOA = 11.99 m LWL = 10.19 m Bmax = 3.45 m Draft = 2.58 m Displ = 5360 kg Sail Area = 90 m2
Builder: Malcolm Runnalls Naval Architecture And Yacht Design, 141 Petra St, East Fremantle, Western Australia, 6158. www.runnallsdesign.com
