That sinking feeling you get when you know something is probably wrong but don’t want to admit it yet hit me as I peered into the stern compartment at the autopilot shelf. We were at anchor in Friday Harbor, and I was doing a routine inspection of our new autopilot system now that we had put it through some rigorous testing.

Sometimes with boats there’s a temptation to stick your head in the sand and ignore possible problems, or not proactively inspect things because you’re afraid of finding a problem. Ignorance is bliss as they say. But this is something I always try to avoid. Ignoring a problem doesn’t make it go away, and with boats it usually will come back to bite you.

On this inspection of our fiberglassed plywood autopilot shelf I saw a small chip or crack in the top layer of ply, which hadn’t been there before. There was no indication the shelf had moved, but it certainly warranted further inspection. For a few hours I agonized over what it would mean if the shelf were failing. I had put a ton of work into researching and installing the autopilot system the best way I knew how, and yet somehow all that due diligence still wasn’t good enough. If this were a real issue it’d mean I’d failed at one of the most important parts of the project.

I knew if I had to rip the shelf out and rebuild it, it’d be undoing the work already done and doing double that to grind it out and build a new, stronger one. But it’s the right thing to do. The autopilot drive puts up to 650 pounds of thrust on this attachment point, and we want to make sure it’s something we can have complete confidence in.

[This is part 3 in a three part series. You can read more about the autopilot install in part 1 and part 2.]

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In part 1 I wrote about some of the planning and decision making process that went into researching an autopilot system for our boat. In this part we’ll get into the technical details of installing a tiller arm and autopilot drive shelf.

The most difficult part of the job, and one that is custom to every boat, was figuring out how to attach a below-decks autopilot drive to the rudder post. Our boat, a C&C Landfall 38, has a pinched stern and very limited space around the Edson radial drive. The autopilot drive is a surprisingly large piece of equipment – about 3 feet long at full extension, and the motor housing is about 8” tall by 9” long.

The attachment of the end of the ram to the steering system is very important because the drive can exert strong forces on the system (650 lbs of peak thrust with the Type 1 unit). The proper way to attach to the rudder shaft is a tiller arm – typically about a 10” long piece of cast bronze that is clamped around the rudder shaft, above or below the radial drive or quadrant. Edson and PYI’s Jefa manufacture them, as well as Buck-Algonquin.

The only problem was our Edson radial drive was already using up nearly all the vertical space available on our rudder stock – of about 4.5”, it uses up 3.75” (the concave disc model). Standard tiller arms are a minimum of 1.75” in height, too large to fit in 1.25” of space.

I looked at all the available tiller arms, measuring and re-measuring, but none of them would fit. Next I considered more drastic options like whether I could move the radial drive up or down to make more space (I couldn’t), and options like flipping the radial drive or buying a new one with a slimmer profile. I talked to people at both Edson and Jefa and both were very helpful, but ultimately this was a very difficult problem – the C&C Landfall 38 simply was designed with a very confined rudder shaft space.

A slimmer Edson radial drive or a Jefa drive with integrated tiller arm might have worked, but would add a substantial amount of work to the project. A radial drive swap isn’t trivial, and each option also would’ve changed the height of the steering cable track, which would require re-engineering the idler shivs to be at an appropriate angle / height (otherwise the steering cable will chafe).

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The decision to add a below-decks autopilot to our boat wasn’t an easy one. For one, it’s expensive, and also a very difficult, time-consuming install. Furthermore, we already have a wheel-mounted autopilot. Why on earth do we need a different one? Then there’s the eternal debate between windvanes vs electric autopilots.

The answer to why we needed a below-decks autopilot is an easy one – our Raymarine ST4000+ wheel pilot simply can’t handle our boat in strong wave conditions, running with a following sea. And that’s the main job we need an autopilot for. The wheel pilot is rated for vessels up to 16,500 lbs, and ours is 17,000 lbs when empty. Loaded with cruising gear it’s likely 19,000-20,000 lbs.

The new autopilot system – Raymarine EV-200

Probably the biggest thing motivating a below-decks autopilot is the memory of our Hecate Strait crossing last June in a gale. I hand steered for almost 18 hours in big, breaking, following seas because the wheel autopilot couldn’t handle it. But there have been plenty of other times where it would’ve been nice to have an autopilot I could have confidence in.

Hecate wave state before it got hard. These were the “easy” waves.

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