Not sure if I have the title of this thread right, but I know what I mean. There seem to be wind vanes on the market. Although not many. And fully mechanical self steerers. And every now and then you come across someone who has retrofitted a tiller pilot to his windvane gear, and reckons it works a treat.
I reckon that makes sense. Fully mechanical systems draw a lot of power, and are fiendishly expensive. Wind vanes seem to be great for long distance cruising, in steady air, and where a few degrees off either way as the wind veers is of little consequence. But have problems downwind.
Even second hand Aries and the like to seem to fetch a couple of thousand dollars in this part of the world-and many of those are 20 or 30 years old.
Maybe what I am looking for is a "make your own" guide. What I'd like is what I think is called a servo pendulum rudder, driven by a small tiller-pilot. The tiller pilot senses a change in direction, it moves the servo rudder, the water kicks the bottom of the rudder to one side, that drives a quadrant which pulls on a rope, which is attached to the main steering wheel, which moves the main rudder. Low current draw, but plenty of power, from the force of water passing the servo rudder. The complex bit must be a two way swivel at the top of the rudder.-the rudder has to be able to turn on a vertical axis, like a normal rudder, but also kick up sideways. But not move fore and aft.
This is for 50' boat in my case. 20 tons.