This function generates a graph which indicates the degree of roll stability the design will have with the current rider and seat position.
The graph is computed as follows:
At each angle ranging from 0 to 30 degrees of roll, the depth of immersion is found. The pitch of the hull is NOT re-evaluated, it is assumed to remain the same with roll. Once the proper depth of immersion is found, to provide the correct bouyancy, the center of bouyancy is located. A torque is computed as the bouyancy times the distance (along X axis) from the center of bouyancy from the combined center of gravity of the hull/rider.
The graph typically looks like the one below:
It indicates that at 0 roll, there is no righting torque, as you would expect. As the roll angle increases, the righting torque also increases. At a certain roll angle, the righting torque begins to decrease, and ultimately it reaches zero. This point, where the righting torque goes to zero, is the point beyond which the hull will capsize (if you don't brace).
A tall wide curve is very stable. A low narrow curve is very unstable.
DONT underestimate the importance of seat height in your design. Try it, and see how this curve changes.
A low seat may make an otherwise unstable design manageable. And, a very high seat can make a design that's plenty big UN-manageable.