Aquatic GPS guided drifter

I would like to build an autopilot system, for oceanographic surveys, which is launched by the shore setting the coordinates and once it arrives at its destination switch off and is carried away by the currents. Once the mission is ended up again and come back to the starting point. It seems possible with this system but what hardware components do I need and which are the best for this application? Thanks

It would be best for you to become a member of the DIY Drones ArduBoat User Group ( and start a discussion concerning your requirements.