The GP26 can be raced with either as many as five crewmembers or as few as three. The cockpit is very big with the mainsheet traveler just aft of the tiller head. If you wonder why a design like this even has a cabintrunk you would find the complexity and thoroughness of the rule interesting when it comes to defining the limits and requirements of headroom. In short, you need 4 feet of headroom over a 3.64-foot length
LOA 25'9"; LWL 21'3"; Beam 8'; Draft 6'3"; Displacement 2,200 lbs.; Ballast 1,100 lbs.; Sail area 370 sq. ft.; SA/D 27.38; D/L 102; L/B 3.2; Auxiliary 4-hp outboard.
Now this GP26 from designer Brooks Dees of Crockett, California, is no family cruiser. This is a pure race boat design within the GP rules that were set up by the ORC (Offshore Racing Congress) and inspired by the success of the TP52 class. The target was a "bang for the buck" box rule class that offered speed and offshore capability combined with low cost. The box rule format means that the rules for the design present the designer with limits, and he must design within a "box," so to speak. This class is up and running in Europe but to my knowledge this is the very first GP26 built in the United States.
For the GP26 the boat cannot be longer than 25.91 feet. Beam must be between 7.22 and 8.36 feet. Displacement must fall between 2,200 and 2,420 pounds. Draft cannot exceed 6.23 feet and the keel weight has to be between 990 and 1,100 pounds. The keel bulb width is limited to 1.3 feet. The rig dimensions are all upper limits except the boom above sheer must fall between 3.7 and 4.1 feet. So while the designer can play within the box for the hull form, the rig is essentially an exercise in using all the maximum allowable dimensions. There are more components to the rule than I have room to go into here but I think you get the idea. When it's all done tight you get the benefit of close, one-design racing with boats that all have some design differences.