jremington:
If the apparent wind shifts 5 degrees to port, you want to steer the boat 5 degrees to port. This is to keep the full power in the sails, and take advantage of any lift. If the apparent wind shifts 5 degrees to starboard, you want to steer the boat 5 degrees to starboard.
Sounds logical, but what will your circuit do when the wind stops, or reverses direction, as it frequently does where I often sail?
The circuit it self will try to keep the boat on course to the wind angle that I have told it to. Me, on the other hand, will probably turn the device off.