The Scanmar
Autohelm auxiliary
rudder is a design that looks good but apparently doesn't
work well. Every one I've seen on a
boat has been a decoration hanging off the back of the
boat in various states of disuse and disrepair. Apparently they don't
work or at least well enough for them to be maintained in working condition. Would be interested in hearing if anyone has had one that's worked successfully for long passages or short.
Because there is a small amount of bleed in a
hydraulic steering system they do not work with direct attachment to a pendulum servo
self steering system. Attach the
self steering directly to the
rudder shaft and bypass the
hydraulic steering with a pressure relief valve and you are in business.
Failing that, you need an aux. rudder self
steering system. If you got fabrication and design skills you try and do it home-brew. Don't expect it to be easy to get a system that will work and certainly not
cheap unless you build it yourself. There a number of auxiliary rudder self
steering systems available but none are
cheap.
Hydrovane, WindPilot Pacific Plus, and
Fleming are some. Have a WindPilot Pacific Plus on the boat and it's worked a charm as long as I tighten the mounting bolts. Sailed the boat DDW to
Hawaii with a relative
wind of less than 10 knots. That's the worst point of sail for a self steering system in light air but the vane did a super job.