This paper proposes to transform a sailboat robot into a big wind turbine (or windmill) corresponding to the boat itself. The main idea is to make the sailboat rotating as fast as possible. When the wind open the sail, the mainsheet is able to pull a generator in order to produce electric energy. The resulting controller is simple to implement and its parameters are easy to tune. A simulated test-case shows that the proposed technique could generate an average power of approximatively 100W