It need not be very expensive though (in terms of what boat
stuff costs, anyway). The main expense would be getting the
frame strong & rigid enough, and after that, providing low
friction bearings to reduce working drag down to the point
where there is sufficient power to control the helm.


Lauri Tarkkonen wrote:
Do the low friction bearings come cheap? I thougt that here the price is
related the other way around, the more friction the cheaper. :-).


Well, sure. All the way down to a rock, which is max
friction but free

The first couple of cheapo rigs I tried had too much
friction. Then I just used a bicycle hub... lasted only a
couple weeks in the salt water, but if you buy a cheap
2nd-hand bike (or steal one) it comes with a spare.



The geometry is worked out and with the tiller you have a continuous
adjustment, because you can attach the line pulling the tiller in
different postiions of the tiller, giving you control of the lever arm.


Right, but unless your tiller in infinitely long, the system
has to generate enough force to move it against weather helm
(up to a point).

There is a clever windvane rig I saw some time ago that used
a tiller pilot for an actuator, and would follow the wind or
the compass depending on which you chose.


I have a good windvane, but while motoring and if I want just a
temporary relief from the helm, I use the tillerpilot. If I know I am
going to sail for the next few hour or more, I rig the windvane.


One of the issues with using a windvane on some boats is
that they generate apparent wind, and can wander all over
the place as the accelerate & decelerate. I heard a story
about a fellow who fitted one to a reasonably fast cruising
cat, and with every gust the boat would accelerate & bear
away, until suddenly it stalled and would almost come to a
stop, and refuse to resume course.

Tiller pilots don't do that, although they do have some
other annoying shortcomings

DSK