Performance Analysis
By making estimates of the forces on a boat, performance figures may be created. Hydrodynamic forces can be predicted in two ways: tank testing, or computational fluid dynamics (CFD). Once the hydrodynamic forces have been estimated, they may be combined with aerodynamic estimates in an iterative fashion in a velocity prediciton program (VPP).
Computation Fluid Dynamics
Computation fluid dynamics generally fall into three types of computations. Potential flow methods require the discretization only of the hull of a ship as well as the free surface. However, all calculations are inviscid due to Green's theorem. Visit my Potential Flow page for information on Michell's theory, boundary integrals, and other codes.
The next type of computation requires volumetric discretization of a domain. The purpose of this Eulerian computation is to investigate the effects of viscosity on a hull form. For a ship, these codes typically use RANS equations (Reynolds-Averaged Navier-Stokes). I have no experience with RANS codes, so I won't embarrass myself by trying to write anything about them.
Finally, a newer method of calculations are particle methods. Each "piece of water" is represented by a particle, or a very small volume. As opposed to Eulerian codes, particle codes utilize the Lagrangian equations of motion, usually in a form as simplistic as the Cauchy equations. However, the enourmous complexity of this method is the "meshless" computation. My Lagrangian Methods page has information on these methods and a few codes of my own.
Tank Testing
Tank testing is the traditional method of calculating hydrodynamic performance of ships. It has been validated by decades of research and continues to be the most accurate form of resistance prediction. My Tank Testing page has information on tank testing and data recovery.
Velocity Prediction Programs
Once resistance predictions have been performed for a yacht, the next step is to link the hydrodynamic data to aerodynamic force predictions. The easiest method of doing this is to create a program which balances the forces and moments on a yacht. By iterating parameters such as hull speed, yaw, heel angle, and rudder angle, the optimum sailing conditions can be found for a yacht around a race course. My VPP page has information on aerodynamics and the creation of a force balancing program.