GP26 offshore sports yacht
The GP 26 is a Grand Prix “BOX RULE” racing yacht introduced and administered by the International ORC organization. This level rating rule class (similar in concept to the TP52) is designed to provide exciting close class racing (without a time allowance or handicap system), be fast, fun to sail, sound and seaworthy with considerable longevity. The structures are designed and built to ABS standards and the standard GP 26 box rule complies with minimum ORC Cat 4 safety regulations for short offshore racing capabilities. Owners have the opportunity and flexibility to select designers and builders to create the fastest boats within the tight shape and construction controls of the box rule. The light displacement combined with generous upwind sail area set on a simple carbon fiber fractional rig (no runners) with non-overlapping jibs and large asymmetric kites simply provides the GP 26 with exciting performance at an affordable cost.
The ORC have set a sensible maximum crew weight of 340 kg which keeps crew to a minimum. Unlike most sports boats the sensible class crew weight limits the amount of crew required to a maximum of 5.
The GP 26 is the perfect racing yacht for the club sailing enthusiast who wants to go fast at an affordable price.
 
From the designer
A local Sydney yachtsman commissioned the first design for a new class of yacht in the range of 26 feet. This was at a time when the newly formulated GP26 rule just beginning to take off, particularly in South America. It was quickly decided that the new design should reflect the GP26 rule and indeed be the first commissioned and built GP26 in Australia.
The design will be sailed predominantly in Australia, along the Eastern seaboard and so the hull form needed to particularly strong on offshore conditions as well as being potent in the light to moderate breezes seen throughout the year.
It was then decided to have involved a recognized builder and Van Munster Boats in Morisset, NSW was a clear choice given their excellent results with skiff building here in Australia. In choosing Van Munster Boats we have a small and dedicated team able to produce a boat to the required weight and to an extremely high level and we appreciate the team coming onboard. 
The design work has been extensive with a matrix of boat shapes tested and culminating in Boat “I” which we felt best represented our initial desires. The GP26 rule clearly defines the rig and sail parameters and so this is our fenced in area from which to place the best combination of hull shape, appendage and bulb configurations along with deck layout and the structural plan. The rule requires ABS to be followed and in setting up the structure and the result is a robust, but relatively lightweight package, that given the required use of E-glass and Epoxy laminates makes for a cost effective approach. It could be argued that the use of carbon in future rule amendments could save cost, due in part to the need for less laminate weight but given the ABS rule, for this size of yacht the use of more traditional laminates will serve the rule well.
Apart for the basic setup of the hull, deck and supporting structure the rule requires a rig weight, at 50kgs this is robust and considering the rule required single spreader setup this is perhaps a good thing. The trick comes in determining the quantity of carbon laminate in the mast tube, certainly adding more can result in a very stiff rig setup, but of course at a cost. The builds currently planned at Van Munster Boats will undergo their construction with a final choice of rig package based on the budget of the client.
Appendage design is tricky, small is fast, but only with speed. Big is best but comes with more drag. In this case we went for the fast option and the devil is always in the detail and how the rig combines with the side force developed by both the keel fin and rudder blade. In the same way the bulb design work looked at short and long forms. The longer bulb chosen reflects our best combination of keel fin weight (rule constraints on keel width and construction) and bulb mass. Getting as much lead as low as possible is the key to getting the righting moment up and perhaps trading off some BWL to get the up-range performance right when heeled along with lighter air modes in general by reducing wetted area.
The deck layout is race orientated, with a choice of longitudinal or transverse headsail sheeting arrangements, again the final choice will be made based on the intended racing of the yacht. With windward leeward course racing suiting the longitudinal approach with in-hauler for tighter sheeting angles and more offshore orientated course racing with the transverse setup. The cockpit is large, wide and shallow for great crew traffic throughout racing and the cabin detail reflects the best way of getting through the IMS based internal headroom and cabin plane requirements. The hard chine / angular approach to the cabin also comes in handy when setting up hardware.
Deck hardware is what we believe to be minimal given the nature of racing the yacht will undertake. There are no line tunnels for halyards, thus saving weight instead we will adopt underdeck jammers and turning blocks to control halyards and other control lines tucked away to keep things clean on deck. All deck hardware will be from Harken through Carl Watson and his team in Sydney. The use of soft padeyes and other weight saving approaches will be utilized.
The final result is a fast, fun small yacht.Really a modern day approach to the quarter tonners of old and a new entry level class that is recognized by the ORC and deemed a Grand Prix class, surely a great thing to want to build and go racing in.
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Standard Construction:
The Hull, Deck and front tank components are all laminated with SP Systems SE84 pre preg system. Plies of uni-directional Pre-preg Carbon fibre are laminated either side of a Phenolic-coated aramid based honeycomb core. 
The Hull, Deck and front tank components are all laminated with SP Systems SE84 pre preg system. Plies of uni-directional Pre-preg Carbon fibre are laminated either side of a Phenolic-coated aramid based honeycomb core.
The Epoxy resin is impregnated into the carbon fibers by machine, which ensures that pre preg laminates have a more consistent wet out and higher fibre content than can be achieved by conventional wet lay up techniques. 
