If you believe all those little electrons will always go to and do what you expect them to do, by all means rely on an autopilot. Personally, the only faith I have in electronics
is that they will screw up, probably when I need them the most. Also, autopilots are hungry beasts, you'll either have to run your engine
every day or so, install a generator
, a windmill, and/or solar panels
. You can easily double/quadruple the cost of an autopilot just to feed it. Of course, since those are electronic entitities in themselves, they are prone to failure as well. Oh, and there are the spares that you should take for the autopilot.
Mechanical windvanes typically work for days/years on end with minimal maintenance
. If you are unfortunate enough for the vane to need service
, it doesn't take an EE degree to figure out how to fix them. The worst problem you'll probably have to deal with is replacing the control lines. With a little ingenuity, you can even set up the mechanical windvane
to steer with a tiller pilot for heading control. Very low electrical
drain since the vane is providing the muscle for steering and low cost.