GP26

offshore sports yacht

The Boat

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 GP 26 delivers exciting performance at an affordable cost. 

• Light displacement
• High ballast ratio
• Generous upwind sail area
• Carbon Rig – simple single spreader
• Non-overlapping jibs
• Large asymmetric Kites
• Simple fun and fast to sail. 

The ORC has set a sensible maximum crew weight of 340 kg which keeps crew to a minimum. This means the boat will be sailed with just 4 or 5 people.

The GP 26 is the perfect yacht for the racing enthusiast who want a custom built boat to compete on a grand Prix level at an affordable price. The current series of GP 26 Class racing yacht are built to the design and engineering specifications of Fred Barrett Yacht design. A considerable amount of detail and computer aided technology has been utilized in the design and build process to ensure that the GP26 is fast, exciting and most importantly fun to sail.   

The design

From Fred Barrett yacht design:

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 was just beginning to take off in South America and some parts of Europe. It was decided that the new design should reflect the GP26 rule and indeed be the first commissioned and built boat in Australia to take advantage of the newly introduced ORCi rating rule.

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 to produce a boat to the required weight and to an extremely high level and we appreciate the team at Van Munster’s 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. 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 quire 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.

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, 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  lines run through underdeck jammers and turning blocks to control the main and jib halyards and other control lines tucked away to keep things clean on deck. Deck hardware has been supplied from Harken through Carl Watson and his team in Sydney. The use of soft padeyes and other weight saving approaches has been 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.

The build-

No expense is spared during construction and boats are manufactured from the most premium materials available to ensure the highest quality product. The hull and deck structures are built from CNC generated tools, the deck in a female and the hull from a male tool.  All Structures are vacuum laminated from SP systems Ampreg 22 epoxy resin system with high grade Corecell foam and unidirectional E- glass reinforcements.

To achieve a beautiful light weight and high strength boat the hull and deck components are Vacuum laminated in a two step Wet preg process. The light weight skins consist of pre impregnated unidirectional fibers which are carefully placed along the predetermined load paths over the tool. The core is sealed and the skins and core are vacuum bagged together in one hit. This process reduced weight in bonding the core to the inside skin and allows any excess resin to be bleed into the consumables pack.The core is then carefully faired and the outside skins are laminated and vacuum bagged in the second step. The hull and deck have not required any fairing compound further saving weight.

Components for the internal structures of the boat are Custom fabricated Duflex panels from ATL composites.  The internals are CNC machined for a precise fit to the hull and deck structures.   The topsides, cockpit sides, cabin sides are finished in high gloss polyurethane, the deck, cabin top and cockpit sole are polyurethane anti- skid finish. The interior is also a superb white hi- gloss polyurethane finish.

Appendages

Rudder –

The Carbon fiber rudder has been built from custom CNC Milled female moulds to produce a lightweight, high strength efficient foil.  The stock is Carbon and to maintain the theme the custom built tiller is finished in high gloss clear carbon. The bearings are JP3 self aligning.

Keel and Bulb –

As dictated by the GP26 class rule the keel shall be steel. So Bisalloy 80 was used in the fabrication of the fin structure. The fin was then filled faired and sheathed in epoxy. All high loaded shear pins and studs are from high strength SAF 2205 stainless. A CNC machined bulb pattern was used to cast the highly efficient lead bulb. The finished arrangement is at class maximum with the lowest possible center of gravity for maximum righting moment.

Rig

After much research and quotes from all of the major mast manufacturers the final decision was to go with C-tech for the rig. C-tech’s innovative approach and experience with high performance small boats was a great match for this project.  They built a beautiful custom carbon pre preg section for this project to fit within the parameters of the GP26 class rules. Sydney rigging specialists have done the rigging and running gear.  Their experience is invaluable to get the best setup and performance out of the rig package.

Electronics

The wireless Tacktick T108 system has been selected for its simplicity, weight saving, no requirement for wiring and it is self powered. The NMEA interface allows for the connection to a laptop and chart plotter.

The Performance

The design study and trial rating certificates suggest that the GP 26 will be very competitive against larger, heavier and more expensive production cruiser/ racers. The VPP model demonstrates the capabilities of very fast speeds in the boats optimum sailing conditions. 

The modern hull form of the GP 26 is well balanced and easily driven and when combined with a high 50% ballast- displacement ratio makes the boat an absolute weapon around the track.

The rig is powerful with generous upwind sail area set up on a simple single spreader carbon fiber rig. Jibs are large and non-overlapping.

The modern hull form and light displacement powered by large mast head asymmetric Spinnakers guarantee exciting skiff style downwind performance.

The simple and clean functional deck layout makes the boat easy to handle for club racing and twilight sailing. Add some of your good sailing mates to the crew and you can go mix it with the big boys in the prestigious grand prix sailing regattas.