Arne,
yes - I lock the main rudder first, but it seems that in some conditions it’s best to leave it centered. Of course even this helps with the weather helm from the aux rudder’s point of view.
I made a ”negative” tiller lock that can be seen on the video (the teak block). I have a 6mm bolt on the tiller, and because the tiller can be lifted more than 90 degrees bacwards, I can insert the bolt in one of the holes on the teak block. This opens up lots of space in the cockpit!
The aux rudder is close to what you drew, but I made it a bit deeper and a bit narrower. I didn’t measure the exact balance, but I think it’s around 20+ %. The aux tiller is very light when you try it by hand.
The vane is based on a 75mm central tube, which means that the movement of the steering ropes is quite short. This is why I have to fix them quite close to the aux rudder’s axle of rotation.
Scott,
Yes, no servo.
I used David Tyler’s plans for the vane part, you can find them in the forum. The aux rudder is about 30-40% of the area of the main rudder.