We just finished up modeling sailboat dynamics and implemented a controller. The dynamics were interesting due to the swinging airfoil. We modeled the winch system using a basic spring model that can only pull the sail in. It works well and can simulate irons, tacking, and jibing. All of the drag coefficients etc. are very rough at this point but the overall dynamics seem realistic.
The sailboat we are using is a 1/3 scale laser sailboat and we hope to have it sailing with the autopilot soon. The autopilot will be implemented for ArduPilotMega using the ArduPilotOne library.
For the controller we are using a feedback system on the rudder to hold the commanded course. We are using a lookup table for the desired sail position given the apparent wind direction.
We have rigged up a wind indicator using a coil wound variable resistor that can easily plug into one of the existing 5 v adc slots on the apm. We removed the stopper so it can freely rotate.