Upgrade: Autopilots Page 2
Installing an Autopilot on a Tiller-Driven Cruiser
When I bought my first boat, a 1976 Bristol 24, it came with a cantankerous Tiller Master autopilot that lacked the oomph to steer the heavy-displacement, full-keel sloop in anything but calm water. I replaced it with an Autohelm ST2000 from Raymarine (the updated model is the Autohelm ST2000 Plus Tiller Pilot and sells for around $700). I could have bought an ST1000, but it was rated for boats displacing 6,600 pounds or less – too close for comfort, in my view, since the Bristol displaced 6,000 pounds.
The installation required tinkering. The Tiller Master was already on a separate fused circuit in the boat’s DC electrical system and was wired to a toggle switch in the lazaret; there was no socket. I used a hole saw to cut a hole to mount the socket for the new autopilot, bedded the socket with silicone, and connected it to the toggle switch so I could turn the autopilot on and off.
For it to work properly, the autopilot had to be positioned level with – and perpendicular to – the tiller. The curve of the Bristol’s tiller made it tough to get the positioning lined up. I used epoxy to glue a block of scrap teak on the starboard cockpit seat abutting the coaming to get the base of the autopilot high enough so that the pushrod would clear the top of the tiller. I then drilled a hole in the block to accept the pin that held the end of the control unit.
I also had to buy and mount a tiller bracket. I drilled two holes in the tiller to take the bracket fasteners, sanded the top of the tiller flat with a belt sander to create a mating surface for the bracket’s flat bottom, and attached the bracket with epoxy to get the ball pin correctly positioned in order to accept the end of the pushrod. I also needed an extender for the pushrod for it to push the tiller well over to port. Without it, I’d have had inadequate turning potential to starboard. The installation took about seven hours and several trips to West Marine.
Selecting an autopilot
When choosing an autopilot, it’s critical to properly account for the boat’s displacement. Factor in the boat’s weight, full tankage (water and fuel), provisions, anchor systems, tenders, and crew, then add at least 20 percent to the weight total. Don’t be tempted to skimp on cost, which starts at around $500 for a basic tiller pilot and goes up from there. If you buy an autopilot with a maximum rating close to the boat’s full-load displacement, chances are high you’ll be disappointed with its performance.
It’s important, too, to consider how much you’re going to use the autopilot and in what sea conditions. An autopilot will steer a boat in calm conditions even if the boat exceeds the autopilot’s maximum rating. A tiller or wheel pilot could be just the ticket for casual, occasional use, but if you plan to rely on it when the wind and seas get up, you’ll need a more-powerful unit, possibly a belowdeck system.
The speed of the autopilot is another important factor. Faster action to put the helm over is better than slower action, particularly for heavy, less-nimble boats. In rough conditions you’ll want the autopilot to respond quickly; it’s a question of performance as much as it is safety.
While a number of companies manufacture autopilots, most focus on belowdeck systems. B&G, ComNav, Furuno, Coursemaster, NKE, Northstar, Raymarine, and Simrad all make belowdeck systems. Currently, only Raymarine makes cockpit autopilots for boats with wheel steering, while it and Simrad offer tillerpilots.
Installing a tiller or wheel pilot is something you can do yourself with basic onboard tools. However, resist the urge to simply wire the autopilot into an existing circuit—say, the one where your GPS resides. The autopilot should be on a separate circuit, and, like all electrical installations, it should comply with
American Boat & Yacht Council (ABYC) standards pertaining to cable type and size. If you aren’t confident about working with your DC system, pay a qualified marine electrician to do the wiring for you, and do the rest of the installation yourself.
A belowdeck system installation, particularly if it connects with hydraulic steering, is way beyond the skill level of most DIY boatowners. Often, this will involve glassing a bracket to the hull on which to mount the drive unit. Hire a professional installer and work closely with the manufacturer or dealer you choose when selecting the components, as they’re complicated and the professional advice will be invaluable.
David W. Shaw is the author of seven nonfiction books. He is a longtime cruiser and contributor to SAIL.