In hull shape studies we use fully appended models with a reference set of rudders, keels and foils. The position of each appendage shifts to match the shape of each candidate hull. For example, the rudders will change angle slightly to remain perpendicular to the hull surface on each hull. For appendage studies we use a set of reference hulls and change appendage concepts, shapes, positions and orientations. Each variation is evaluated by comparing the resulting forces (drag, side force, roll and yaw moments) and by comparing the flow characteristics using stream lines and other visualization techniques.

Our hull shape research program is quite extensive. The design spiral begins with the required transverse stability and waterline beam. We then obtain accurate sail force coefficients using our own aerodynamic simulations. Different sail sets are tested for upwind and downwind sailing in light and heavy conditions. This is important, especially for very beamy boats, because the sail forces can have a large effect on the longitudinal trim which changes the drag. Instead of attempting to match a given sail set to specific sailing conditions, which is difficult and error prone, we find the center of effort for the sails and apply a force vector at that point in the hydrodynamic model. Then the hydrodynamic simulation runs so the drag on the boat matches the force generated by the sails. The hull shape investigation continues with studies of volume distribution, prismatic coefficient, transom width and immersion, bow fullness, etc. Hull shapes are organized with parent hull shapes and their derivatives. This allows for easy analysis of trends and performance drivers and final selection of a hull shape.