Compass controlled servo and rudder

Hi

I am trying to achieve the same as demonstrated on tuckertiki.co.nz for my kontiki

It is a device that you simply point it in the direction you want it to head in then power it on at which time it locks in the heading and then as it heads out to sea as the heading changes the magnetic compass controlled servo changes the position of the rudder to compensate and get it back onto its heading.

Does anyone have any suggestions for already completed gear that may do what I want?

I can build the board and program a pic microcontroller with the firmware but I don't understand what equipment I will need to complete it.
I have googled around and found magnetic compass modules and there are plenty of autopilots out there using arduino or picaxe but they all seem to have integrated gps as well.

Thanks
Steve

if your Kontiki is a sailing boat then you really want wind powered self steering gear as invented by "Blondie" Hasler. If you try to sail on a compass heading then if the wind shifts you could stop.
Frank

Thanks for the reply. No it has no sailm just an electric motor which hauls out a fishing line until the pic controller timer stops the motor. It shouldn't really be affected by wind, just strong current/rips etc but with an auto adjusting rudder eventually it should make it through the white water and currents and then continue to its destination okay.

Cheers
Steve