Sailboat autopilot

So I’m hoping to build one of these. The device will need to be able to maintain a compass heading and also should be able to steer to wind… from a NMEA0183 data stream. I guess to start with I will just want it to steer the sailboat in a straight line. The autopilot will need to have an IMU and I’m thinking PID control will handle the out put which will drive a hydraulic pump connected to a cylinder which will activate the tiller arm, thus steering the boat.

My first issue is which controller? I’m tempted to go with the SVP-1284 right away, but I need something that will drive a 6amp 12volt motor …with peak output somewhere around 15 amps. I only need the one output. Inputs need to be a few discreets (maybe 5)

Any help with choosing components would be greatly appreciated.

Sounds like a fun project! The first hurdle is to get the steering hardware working, then you can choose a controller based on the steering motor requirements. The steering mechanism for an autopilot that I’ve used on a 26 foot racing vessel consisted of a surprisingly low power DC motor, with a small pulley driving a belt wrapped around the helm wheel. Very little steering motion is required with this setup and it is trivial to override it in a panic.

There is lots of cool hardware to look at on line, for example: edsonmarine.com/marinestore/ … x&cPath=84

[quote=“Jim Remington”]Sounds like a fun project! The first hurdle is to get the steering hardware working, then you can choose a controller based on the steering motor requirements. The steering mechanism for an autopilot that I’ve used on a 26 foot racing vessel consisted of a surprisingly low power DC motor, with a small pulley driving a belt wrapped around the helm wheel. Very little steering motion is required with this setup and it is trivial to override it in a panic.

There is lots of cool hardware to look at on line, for example: edsonmarine.com/marinestore/ … x&cPath=84[/quote]

Thanks for that reply Jim. It sounds like you have built one of these… would you care to share video or other information? For my purposes I will probably use a hydraulic type 0.5 pump to drive the tiller hydraulic ram …a pump like this raymarine one: raymarine.com/view/?id=211
The literature says this pump will need 9 amps to develop 55 bar.

I did not build the steering system that I described, sorry that you got that impression. However, I marveled at its simplicity and effectiveness. Inspired by that, for several years I have been building navigational and control systems for small autonomous models.

If you need a hydraulic system to operate the tiller, it would seem that the boat is pretty big. How do you plan to override the control system in an emergency, like an impending collision?

My plan is to have a pin on the tiller end that I will simply lift off the tiller. The existing Simrad TP32 pilot that I have uses such a method. The hydraulic arm will be mounted above deck. To turn the pilot off I will use a switch, so that the ram is not activated/moving unless is is connected to the tiller.

This video shows a homebrew course/autopIlot using the Simrad TP 32 motor only (the autopilot control has been replaced by the users own design)
It shows the attachment method well.


My boat displaces 21 000 lbs and I would like to use a more robust drive. My Simrad TP 32 is starting to show signs of impending failure and it is not very old. The hydraulic system should work well, be responsive enough and last a long time.

Jim, I’m interested in the pilot control that you built for a racing sailboat. What sort of displacement and type of boat was it for? I race my boat and the autopilot performance is so important to good sailing performance.

Again, I did NOT build the autopilot system on the racing sailboat. I’ll contact the boat’s owner for the details, but it may be a while before he responds.