Two Adults, 408 Hours: Why I'm Budgeting for the Autopilot Like a Third Crew Member

Two thousand eight hundred nautical miles in 17 days works out to roughly 408 hours at the helm, and on our boat there will be exactly two adults to share them. That is the number I keep coming back to when people ask what I'm most worried about on the Atlantic crossing. It isn't the weather. It isn't the rig. It's the box that holds a heading while we sleep.

On the 50-foot cat we're researching, the autopilot will steer something like 95 percent of our miles. Hand steering a loaded cruising catamaran, with four kids' worth of gear aboard and a following sea lifting the quarter, is a two-hour-shift job at best and a miserable one at worst. If the pilot dies in mid-Atlantic, we don't have a minor inconvenience. We have two tired people trying to run a family and a boat on a rota that was never designed for it.

So I've started budgeting for the autopilot the way I'd budget for a third adult. Here is how I'm thinking about it.

The failure I'm actually planning around

When I read cruiser logs and forum threads about pilot failures offshore, the story is rarely "the whole system died." It's almost always one component. The drive unit wears out or loses a seal. The course computer takes a voltage spike and goes quiet. The rudder reference sensor drifts or its linkage works loose, and the pilot starts hunting. The heading sensor gets confused by something metallic someone stowed next to it. Each of those is a small, cheap-ish part, and each of them takes the entire pilot out of service.

That framing changes what you buy. Most people shop for the pilot by brand and feature list: Raymarine Evolution, B&G with the H5000 or NAC-3 processor, Garmin Reactor 40, Simrad. All of those are credible. What matters more, I think, is how many of the individual parts you carry as spares, and whether you know how to swap them in a seaway at 2 a.m.

My working rule: for every part that can stop the pilot, I want either a spare on the boat or a clear plan for steering without it. Anything that's both single-point and not in the spares locker is a risk I haven't priced yet.

What a cat asks of a pilot that a monohull doesn't

A catamaran is a different steering problem. Twin rudders are typically linked by a tie bar or driven through a hydraulic system, and the pilot's drive unit has to move both of them. The boat is fast and light-feeling, but the apparent wind swings dramatically as speed builds, so a boat doing 9 knots in 18 knots of true wind sees a very different wind angle than it did at 6. In following seas, a cat can surf and yaw, and the pilot has to catch the swing before it becomes a round-up or a gybe.

The practical consequences are these:

• Drive unit sizing. Under-sizing the drive is the classic mistake. A pilot working near its limit in 25 knots is a pilot that overheats, wears faster and gives up exactly when you need it. I'd rather over-spec the drive by one step than save a few hundred dollars.
• Rudder reference placement. The sensor needs a clean, rigid mechanical connection. Check how it's mounted on any boat you're inspecting. If it's held by a bracket that someone bent into place, ask what else was improvised.
• Heading sensor location. Keep it away from steel, speakers, and anything that carries heavy DC current. Cats have lots of cable runs, and a fluxgate or heading sensor mounted beside a battery cable is an invitation to a drifting course.

Power: the pilot is not the problem, the bank is

A pilot in moderate conditions on a boat this size draws in the neighborhood of 3 to 6 amps at 12 volts, and more when the seas get lumpy. That's not much against a big lithium bank and decent solar. What worries me is the other direction: the pilot is only as reliable as the supply behind it. A lithium bank that disconnects itself on a protection event, or a voltage dip when a big load kicks in, can take the pilot and the plotter down in the same second. I wrote about that failure mode when I looked at alternators and lithium last week. The point for this post is simpler: I want the autopilot and the chartplotter on a supply that survives a bank shutdown. On a Victron-based system, that means thinking carefully about which loads sit behind the BMS cutoff and which don't.

It also means logging amp draw on the first sea trial. If you know what the pilot pulls in 15 knots, 20 knots and 25 knots, you'll notice when something changes. A pilot suddenly pulling a third more current is usually telling you the drive is working harder than it should, and that's a warning you can act on before it fails.

The spares list I'd actually carry

Here's where I've landed for our boat, working from the idea that every single-point failure needs an answer. These are budget figures I'm using for planning, not quotes, so check them against current pricing before you rely on them:

• A complete spare drive unit, matched to the one installed. My planning number for the installed primary system is roughly $6,000 to $9,000 including labor, and the spare drive and a spare course computer are a few thousand more on top.
• A spare course computer or control unit, stored dry and tested before departure, not after.
• A spare rudder reference sensor, with the linkage hardware.
• A spare heading sensor or compass, plus the cabling to fit it.
• A handheld or wireless remote, so whoever is on watch can adjust the heading from the cockpit or from inside, and can steer while standing at the mast or the winch.

That's a real chunk of money. Spend it anyway. Compared with the cost of the boat, it's a rounding error. Compared with the cost of a bad crossing with small children aboard, it's cheap.

I'd also keep a written, laminated swap procedure. I'm not going to remember which connector goes where when I'm tired and the boat is moving.

What about a wind vane?

On a monohull, an independent wind vane is the classic answer to "what if the electric pilot dies." On a catamaran, it's much harder. The wide stern, the twin rudders, and the structure aft make most mounting arrangements awkward, and the vane has to deal with a boat whose apparent wind changes quickly. I've looked at the options and decided I'm not going to rely on one for our boat. If I'm wrong, it will be because someone builds a cat-specific installation that's well proven offshore. I haven't found one yet.

Steering without the pilot: practice before you need it

The last piece is the one nobody likes. If the pilot is gone and no spare fixes it, you will hand steer. The question is how long you can do that safely.

My plan is to practice it before departure, on purpose. Hand steer the boat for a couple of hours in 15 to 20 knots, then for a longer stretch, at night, and see how tired we are. Time it. Decide in advance what the fallback is: reef earlier than the 20-knot rule says, slow the boat to a speed you can actually manage, and shorten the shifts to an hour or two. A cat doing 5 knots under control, hand steered by a rested person, is a better outcome than a cat doing 9 and steering itself badly.

We'll also need to teach the older kids what a hand-steered watch looks like. Not as crew, but so they understand why Dad is up and why we're going slower.

What changes if I'm right

If the autopilot really is the third adult, then three things change in how I evaluate a boat. First, I look at the steering and pilot installation before I look at the saloon. A boat with a clean, well-documented drive installation and a spares kit is worth more to me than one with newer cushions. Second, I add the cost of a complete spares set, roughly $8,000 to $13,000 on my working numbers, to the purchase budget rather than treating it as something I'll get to later. Third, I stop thinking about the autopilot as an electronics purchase and start thinking about it as part of the crew plan.

The next step for us is to go through the steering systems on the boats at the top of our list and write down, for each one, the make and model of the drive, where the rudder reference sensor is mounted, and what's in the spares locker. That list will tell me more about each boat than the brochure does.