What! Nobody recommending build it yourself! The Cal
34 I took to Hawaii
had a homebuilt electric autopilot
built by a previous owner, and I built a horizontal pivot windvane from a design in Belcher's book.
The autopilot had one failure on the way there. The actuator arm had two bolts screwed into it to form a fork that you dropped the tiller into. Part way into the trip one of the bolts sheared off. Murphy's law being in effect, I had just dropped into the cabin
to get my foulies because I saw rain in the distance. The boat jibed while I was below once the tiller was free. The boom vang
rigged as a preventer, prevented the boom from jibing, from the vang to the mast
, the rest of the boom jibed. Two hours later after screwing aluminum
U channel onto three sides of the boom to put it back together, and 5 minutes to put a new screw in the autopilot we were back to normal, except for our mental state.
What I really liked about the homebuilt autopilot was that the three knobs were labeled P,I,D which makes sense to me, I always have to think about what the terms created for boats mean. Also the P,I,D controls had a lot of range, the ST4000 I have now drives me crazy because the minimum integral you can set is way too long for certain conditions.
The windvane was made out of plywood
and a broken laser mast
section. The two part mast made the part to swivel the vane sail. The design I picked was for a 30' boat, so between being too small and not a servo pendulum design I was pretty sure it wouldn't have enough power for downwind sailing, and I was right. The autopilot was used for downwind.
The windvane steered us for nearly the entire trip back. Once again Murphy caused the high to move northwest of us when we were supposed to get into the westerlies, and we wound up close reaching on the other tack on our easting. A mechanical engineer
told us that the windvane wouldn't last a day out there. The only thing that broke on the windvane was a cheap
cast cleat that we found laying around, that as soon as I tried to tighten a line on, the arms snapped off.
Well 20 years ago things were a bit different.