DIY Autopilot

Hi,

I am planning to build an autopilot for my boat. Actually I've already build/programmed the compass and control unit. First I was planning to use a below deck Linear actuator for controlling the rudder. Unfortunately this is not possible due to lack of space. Now I am thinking maybe I could use a belt drive on the steering wheel. There is a commercial party that uses the same concept, see there website for details: http://www.cptautopilot.com/

The problem is I can't find a good motor, belt and gear. Does anybody have some suggestions where to start looking?

Thanks!

Arne

Here are some belts/pulleys that are too small for you I think: http://www.rapidonline.com/electrical-power/toothed-timing-pulleys-and-belts-71294/, but the thing to search for is "timing belt" and "toothed belt" I think.

For motor a stepper motor might be good (no holes to let splashes in like a DC motor!). Some sort of indexing scheme might be
needed, at least at power up. You'll need to investigate how much torque will be needed, and you'll need a manual override
option as steppers hold position strongly. Continuous rotation servo is another possibility - but first you'll need to get an
idea of the forces / torques needed. And find a supplier for large pulleys for toothed belts (unusual item) - or even gear wheel
(nylon gears would be corrosion-proof).

I know of steering engines that do exactly what you described.
They use a windshield wiper motor (at 24 volts) for electrical steering, which can be controlled by autopilots.
Be aware that when you do this, your steering wheel will be turning when the motor is controlling it, which is a real danger.
The system i know of, has some kind of clutch that connects either the wheel or the motor to the steering axle.
The motor or steering wheel aren’t directly coupled with the rudder, but are controlling a hydraulic sytem but those are commercial vessels.

www.sdp-si.com is also a good source for timing belts/pulleys. An XL (1/5 inch pitch) would be about the right size. A 1/2" wide belt would be stronger than you could ever hope to break with your bare hands/feet.

A big pulley like the one shown in the picture is not likely to be available. Something you can try is making a wood disc and wrapping the outside with a timing belt turned inside-out. That worked for me once but I had a closer pulley ratio; it might go out of whack with a higher ratio. Might not even need teeth on the big pulley, really.

arne81:
Hi,

I am planning to build an autopilot for my boat. Actually I’ve already build/programmed the compass and control unit. First I was planning to use a below deck Linear actuator for controlling the rudder. Unfortunately this is not possible due to lack of space. Now I am thinking maybe I could use a belt drive on the steering wheel. There is a commercial party that uses the same concept, see there website for details: http://www.cptautopilot.com/

The problem is I can’t find a good motor, belt and gear. Does anybody have some suggestions where to start looking?

Thanks!

Arne

Just take a look in my project:

Regards

Rabadak