Thanks Annie,
I have a confession; I built about 95% of a Belcher OGT1, and have discarded it. When I test mounted it on the pushpit, high enough for the counter weight part to clear the pushpit, the whole thing was so huge that it looked more like a mizzen!
It's hideous hugeness, plus something Chris Gallienne said (about the torque needed on the tiller when the wind is a abaft the beam) was enough for me to give up on the OGT1. I also went and had a second look at the two or three blogs that described having built an OGT1, and had a look at their latest blog posts, and noticed that none of them were still using it.
So I'll take Arne's advice; go sailing and see how Mariposa behaves, then decide. So I've bought myself an electronic tiller pilot and installed it, and as soon as the weather is favourable the dog and I will leave dreary Plymouth for foreign shores!
If the tiller pilot will put up with my abuse for the summer, I'll tackle a windvane project during the winter (while teaching English in Spain, if all goes to plan).
By the way Annie, where can I find pictures and description of the self steering windvane solution you went for on Fantail? I presume you wrote a blog post about it, but I can't find it.
Best, Matt