Now that you have set up everything, pack up your electronics in any sort of water-resistant plastic case, and your sailboat should be ready to sail.
One word of caution
Electronics and water normally do not mix well. Make sure that your BeagleBone Black and all the associated circuitry is well buttoned up in as watertight a container as possible. Use a silicon sealant or some other waterproof sealant from where your wires enter or leave the enclosure.
Your sailboat can now sense wind, control the rudder and sail, know where it is and what speed and angle it is moving at, and calculate the bearing and distance to a new destination. In order to complete your robot, you'll need a bit of information on how to sail. First, ...