Homemade tiller autopilot

[GILow]

Some pretty bizarre claims about power consumption there. :^)

[Dave9111]

I don't think he is measuring/calculating power correctly.

I think that you can get by with a PID auto pilot controller if you have a full keel. A full keel boat wants to go straight. My first experience with a homebuilt autopilot was on an Ericson 29 tall mast. That is an IOR design which is really good at going around buoys but not so great in tracking in a straight line. Downwind sailing in that boat with some wind was simply scary. It constantly wanted to "round up". It was a tiller boat and that was appropriate as on anything except a broad reach I was constantly moving the tiller. Rather than sailing straight downwind I would sail slightly off the wind and that helped a lot.

So keep in mind that the needed intelligence of your autopilot may depend on your boat design. Also, if you have a hard time controlling the boat with a tiller by hand, it won't be better with an autopilot.

For the same reason, an autopilot on a power boat is entirely different than an autopilot on a sailboat. A power boat will tend to go straight if the wheel is centered.

[IdoraKeeper]

Curious why a hydraulic ram is not being considered..A robust pump will not have the duty cycle issues of an electric linear actuator. I like these ideas..especially the repurposed cell phone. I hope those of you working on this will continue to post your progress..

[Dave9111]

I don't think there is an issue with the actuator. Hydraulic should work as well as electric assuming that the device is sufficiently stout. I bought a outboard hydraulic actuator and a couple of autopilot electric pumps off Ebay. I want to set mine up for below deck. Keeping it out of the weather should help reliability. My first homemade autopilot used a generic chinese electric actuator and it worked ok. I could have been faster, but the controls could not keep up with the boats dynamics as I previously described. Way too non linear.
My current boat, a Pearson 10M, has a Autohelm 4000 with a wheel pilot setup very similar to what Raymarine sells today. (They bought Autohelm). That uses a DC motor that drives a planetary gearbox to drive a toothed belt that spins the wheel. The motor hunts a lot! But it works. I had to replace the motor since water got into it. It seems to move the motor every second or so. The gearbox is noisy, so I know when it is working. Compared the my previous Ericson 29, the Pearson 10m is an easy boat to sail. It has a lot more weight and ballast and a much longer waterline.