Monday, June 10, 2019

We have put the boat up for sale. 19 years of a pretend autopilot, and just now I have ordered parts for a real autopilot! Why did I wait so long?

We have hydraulic steering, which made it difficult to choose a servo-pendulum wind vane for steering, but we did choose a Cape Horn. I put a small tiller pilot on the wind sensor for the Cape Horn and let it be the autopilot. It worked ok for most wind conditions across the Pacific, but that was mostly downwind. It does not steer well if the wind is forward of the beam. Also the little tiller pilots only lasted about 15,000 miles each. That means the current one (the third) is due for failure any time now. Also it was very difficult to set and to disengage. Trinda couldn't manage it. One had to get on course, steer straight then tighten 2 ropes to the wind vane, and pull a cable like a manual choke that disengages the wheel, then activate the tiller pilot.

Therefore, I ordered an electric hydraulic steering pump from the the folks that manufacture most of the pumps for the brands of commercial autopilots. It is the Octopus 2.0 liter/minute 12volt pump.And a few other parts for the boat, like shackles and T-bolts, zincs and a new Mic for the radio.

I ordered a new, custom autopilot control system from It has 2 major components, a course computer and a motor controller. The course computer is based on the small ARM computer boards that I have been playing with recently. It has a totally electronic 9-axis inertia motion sensor instead of the old flux-gate type of electronic compass that were so picky about placement. It can be easily integrated with opencpn, my favorite choice for navigation software.

A big reason for choosing pypilot is, since the boat is for sale and most new owners are very choosy about the brand of instruments, pypilot gets me equal or better features, possibilities for enhancement and does not make the choice of integrated system vendor for any potential buyer. It was also very inexpensive compared to the brand name stuff.

Large motor controller

Course computer consists of keypad,remote, display and IMU and Raspberry Pi Zero W

The pump is heavy duty and draws 6 to 8 amps normally but as much as 22 under stress. That meant I must use the large motor controller from pypilot.

The small motor controller is good for up to 3 amps. Several folks are using an old car windshield wiper motor with it's reduction gear to make their own wheel pilots and tiller pilots. If I can find such a motor I may try for a wheel pilot also. It might use less power when sailing in nice conditions. The small motor controller is in a case like the course computer will be in, only 1.5x2x3 inches.

The next problem was finding a hydraulic supply for the hoses and connectors to install the pump. Having no Japanese didn't help, but I did find one, "Only a 20 minute walk.", says Google maps! They must be young kids!

I did get it installed. The course computer needs to know the position of the rudder to keep from trying to turn past the stops and to adjust for currents and in general. I made a custom rudder position indicator from a precision potentiometer.

I hope to give more progress reports as I finish.