One thing I've been finding is that the vane axis must remain either horizontal, or inclined with its forward end higher at all times, or it becomes unstable. This is fine, with the vane axis horizontal and parallel to the base on which the vane turret is mounted, so long as that base remains truly horizontal. When sailing to windward or on a beam reach, the angle of heel will supply a little positive inclination. On a run, it doesn't. If the whole gear droops down aft, even if only by a little, the vane axis inclination goes negative and the stability of the steering is adversely affected. So my current thinking is to build in a little insurance by inclining the vane axis at say 2°, and then also raking the whole gear forward by 2°. This would give 4° of inclination when running, reducing to 0° when head to wind.

Arne Kverneland wrote:

Most elegant, David!

It slowly dawns to me how the whole thing works and produces a bit negative feedback to prevent over-steering (those canted hinges, right?). However, it is like with the Wankel engine and Stirling engine  -  I only have a very loose idea on how they work...

Arne

Well, you're way ahead of me, Arne. I'm hoping for a full theory of operation description, because I'm pretty much baffled as to what we're talking about here. 

https://goo.gl/photos/7xUQYQ2vTYhDY4rW6

A short video of the vane gear holding a steady course on a beam reach.

David

That all sounds very positive.  You must be pleased with the results. I follow with interest.

Peter

This is very encouraging. The first passage, from Ravenglass to the Fleet Isles went well, with the gear steering well on a reach. I've just weighed and sailed out on a run, the apparent wind is only just strong enough to feel, and the course keeping is very good. One liitle experiment is working, I'm glad to say. I have the course setting lines such that if they are cleated, they add in some negative feedback on tip of that inherent in the Hebridean design. For anyone used to conventional vanes on fixed base, it takes some getting used to, to see the turrent swaying to and fro, and also rotating a little at the same time. Weaverbird is quite twitchy to steer, and reacts very quickly. I don't think any other design could cope as well.