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My big winter project was installing a Raymarine EV-100 autopilot using the tiller actuator below deck. I used Boat's approach to doing this. I do not like the idea of using a wheel autopilot/donut approach. I was willing to accept a 30 degree travel limitation. I am using an NMEA network and a Lowerance HDS-8 chart plotter. Yesterday I took my M out for a test run at the lake before my one week trip to San Juans. Here are my results if your interested in this approach.

The autopilot did an excellent job holding a heading under sail and motoring with dagger board and rudders down and with dagger board and rudders up.

Using the chart plotter the autopilot did track a course but tended to wander slightly trying to stay on course,

The reduced travel to 30 degrees was NOT a factor at all. The heading change response was very good.

The autopilot was silent while operating.

Engaging and disengaging the autopilot was flawless. Rather than an electrical connector for the ball receiver , I machined a 3 inch con caved disk attached to the tiller arm per Boat's design and used a 3/4 inch ball on the end of a threaded shaft attached to the steering actuator . This reduced the precision required on the wheel to engage the autopilot. It worked flawlessly.

As noted by Boat, you need to ensure the autopilot linkage is engaged before you turn on the autopilot and need to get the wheel centered then turn autopilot to standby and then raise the ball from the cup i.e. disengage the autopilot.

I have seen people say that an addition of an autopilot was the best mod made and I have to agree.

Estate Sail wrote:Using the chart plotter the autopilot did track a course but tended to wander slightly trying to stay on course.

Presumably there are adjustable parameters for proportional, differential, and integral variables (like any PDI control loop), but I've never tweaked one, so I'm just asking.

My last boat had an autohelm, which was a really great thing to have, but it worked well and I never had to adjust anything. I keep thinking it might be a nice addition to Tomfoolery.

The reason the tiller AP more accurate than the wheel pilot is because the tiller pilot bypasses all the sloppy steering linkage on our MAC boats. I think I have the tightest wheel linkage in the fleet with only ¾ inch play in my wheel but that’s ¾ inch the AP is not needing to compensate for all the time. Most MAC's have almost 2 inches of play in the helm wheel. You eliminate all that play for the AP by having the piston steering directly connected to the rudder - it's as accurate as you can get.


I’m always looking for a better way to do that mouse trap below decks that traps the piston arm onto the tiller arm – if you have pictures of that it would be good to see for others too. I am always thinking of ways to improve. I have found the whole system to be flawless – it works perfectly. The only issue is; as you said, making sure your lined up well before you drop the piston on the tiller arm. I did figure out how to center the piston from the helm by using the JOG STEER feature for those times when the piston got moved because I forgot to turn it off.


As for using the chart-plotter to control the pilot I am not sure if the defaults on the plotter pilot mode change from performance to sport or whatever – it all depends on who is really in charge, (the plotter or the pilot) – if the chart-plotter is sending constant course corrections to the AP then you will wander a bit – I did not set up my chart-plotter that way – I have my chart-plotter only sending GPS WAY-POINTS to the AP, so the plotter never even gets involved in the whole navigation process until a new way-point is sent. All my plotter does is send the way-point – it’s up to the Ray-Marine pilot to navigate to the GPS coordinates of the way-point then until the way-point is achieved. When the existing way-point is within a set parameter the plotter sends a new way-point (the next leg) but the RAY MARINE unis is still in control - it will not make the course change until I respond to a course change alarm - it beeps an alarm asking for my approval of the new way-point about 100 feet before I reach it - I can set feet or miles for the alarm.

Most of you sailing inlets, bays, and lakes would not want to set up you plotter like mine - I sail in the ocean so a delay in my course change is no big deal - there is nothing out there. Most of you would use the plotter itselve to do the navigation because you probably have complicated way-points, legs, and obstacles or depth warnings you want the plotter to steer clear. I do have a saved plot like that to steer the boat into and out of the harbor under power from the launch ramp (5 knots speed) in case I want to pack sails or hang fenders do chores away from the helm while the boat is coming in to the ramp. That's the only programmed course I use.

If I use the AVOID OBSTACLES or SMART PILOT or the AIS NAVIGATION features of my Garmin Chart-plotter then it will indeed take over the whole process and the course does wander more.

Under PERFORMANCE MODE the pilot is so accurate it hardly varies even 1/2 degree. It’s solid.

Estate Sail, I too would love to see pics and description of your "mousetrap".

I'm planning to install a below deck tiller pilot on my 2009M. Having spent the last week reading everything relevant, my feeling is that the Ram/Tiller interface is the trickiest issue.

I'm sure I'll be back for help as the installation progresses as I'm not an engineer; just a wannabe.

Many thanks to you all, especially BOAT, for making the journey so helpful and entertaining.

Can you show a pic of your connection tiller rod / steering?

And: For autotacking: What course did you put to the ev-100? I just come home from 2 weeks cornat sailing after testing BOATs ev-100 system either. Works great. But I put 120degree for autotack. What have others?

What settings are you guys using with the ev100 wheel pilot? Power boat, sail or fast sail? What degree on the turn?

kurz wrote:Can you show a pic of your connection tiller rod / steering?

And: For autotacking: What course did you put to the ev-100? I just come home from 2 weeks cornat sailing after testing BOATs ev-100 system either. Works great. But I put 120degree for autotack. What have others?

120 is good - for really light winds you can use 150

The wheel pilot uses a different hard over time than the tiller pilot because the tiller pilot is limited in it's total arc and the wheel pilot is not.