Downwind Self-Steering

[charliehows]

i'm working on building a double rudder servo pendulum windvane unit for my centre cockpit hydraulic steering ketch - i built a servo pendulum unit but the hydraulic steering defeated it. once i balance the sails my boat steers pretty well anywhere from closehaul to reach, i really only need steering when the wind has to be put aft of the beam, i'm starting to wonder if i want to spend all the time and energy building a double rudder servo unit which probably wont work all that great downwind. I'd appreciate any ideas/experience/ opinions. At the moment im working on a rudder lock which is a prerequisite for the aux rudder unit and i'm planning some seatrials with the rudder lock to see if any sail combos work downwind - i'd be happy if i could get control 15 - 20deg off ddw, i dont mind tacking downwind if i can get time off the wheel

[s/v Beth]

Twizzle rig. I am going to see if it works with a main and jib (wing on wing). Will let you know. Sailing has kinda stopped here for a while....

[roverhi]

I've got the WindPilot Pacific Plus on my Pearson 35. It's a pendulum servo vane driving an auxillary rudder which is what I think you are talking about. WINDPILOT - Products: Pacific Plus

It worked fine for me on a recent dead downwind sail to Hawaii. The trades were a little light and rairly saw 8k relative wind and often 5k or slightly less. Ran wing and wing DDW for 12 days with the vane steering all the way. Days runs were from 140-155nm.

I made a lightweight 8"x4' corrugated plastic vane to make the vane more sensitive. Used it most of the way. Changed to the larger plastic vane when the stock plywood vane was allowing the boat to yaw too much.

[delmarrey]

That's what I found on my Monitor!
With the larger vane that monitor supplies I can DW sail as low as 8 kt windspeed then it starts to yaw. So I've built a wider vane to take more air resistance. I haven't had the chance to try it yet but I'm hopping it'll do the job.

[boden36]

What do you mean by "The hydraulic steering defeated it"? If you put a connecting line between the two lines going to your slave cylinder, and a ball valve in that line, when the valve is open, the hydraulic steering should have little effect on how your windvane performs.
Regards,
Richard.

[roverhi]

Pendulum Servo Vanes connected to the wheel on a Hydraulic Steering boat don't work well. There is enough pressure loss in the hydraulic system so the wheel needs constant adjustment to maintain a certain amount of rudder deflection. Without constant adjustment of the wheel, the vane's servo rudder will run out of enough deflection to steer the boat.

You have to bypass the hydraulic steering and go direct to the quadrant or tiller and then use a pressure relief valve to disable the hydraulic steering while the vane is steering the rudder directly as you said.