The final GBR99 design was arrived at by approaching it in an altogether different way. Delftship allows verious separate parts to be designed, automatically patches them together and fairs the result. The design was achieved by:
The above-waterline hull, "A"
The below-waterline hull, "B"
The combined hulls from underneath, "A+B"
The combined hulls from bow and stern
The "B" hull sticks through the bottom of the "A" hull, forming a natural crease-line that remains below the waterline, except in the permitted region by the rudder-post. This crease-line blends into the smooth hull just aft of the section of maximum beam. The result is a bustle that tapers more gradually than a Norlin III. Less buoyancy in the stern means that the ballasted keel is a little further foward to maintain level trim, so the whole sail rig must also be a bit further forward to maintain balance. The rear view shows the shape of the transom-section former - the actual transom will be classically sloped.
We will see later (October 2011) that, although this design is supposed to have 292Kg displacement, it is deficient by some 30kg because Delftship adds in the underwater volume of Hull A that lies inside Hull B. This has a severe effect on the rating and remedial action will need to be taken to eliminate the displacement penalty.