How fuzzy math made me kill the engine and save my sailing soul

In my fantasies about my next boat, I specify a custom-built racing-cruising sailboat with a lightweight composite hull, a lifting keel, a tall sloop rig with a generous mainsail, fractional, non-overlapping headsails and masthead spinnakers—and a humongous engine.

That’s right, a big, brawny diesel. I include it in my game of fantasy sailing because when you start the engine you instantly destroy most of the sensory pleasures of sailing. If you’re going to do that, you might as well have a power plant that can drive the boat into head seas at hull speed and has plenty oomph for maneuvering in adverse conditions.

That’s the same reason I find the cliche of sailors retiring into trawler yachts amusing. If you were going to put up with the godawful racket of an engine running all the time, with no chance of a respite by raising sails, why would you want to plod along in a displacement hull at a jogger’s pace? If I ever sold out to the dark side, I’d want the fastest, sexiest stinkpot I could afford.

I have to admit, though, to spending a lot of time acting as though my sailboat is a trawler, the engine banging away, spewing decibels into cabin and cockpit hour after ear-aching hour. This can be easily rationalized. The wind is unreliable. We have to be somewhere at a certain time. God forbid we should have to sail to windward when not racing.

It’s not that I’m hopelessly dependent on the engine. I’ve docked under sail and escaped breezy anchorages under sail. But that was because I had to—the engine failed. Otherwise I’m delighted to use it when it makes a sailor’s life easier. Deciding when to turn it on isn’t so much the problem; it’s when to turn it off. When it’s running it numbs the ability to sense nuances of wind and water with the result that fine moments of sailing are missed. It took some sloppy math to teach me that last summer.

We left Mackinac Island at the top of Lake Huron on a promising, clear morning, bound for Port Huron, 220 nautical miles away at the bottom end of the lake. We expected to power most of the way—the forecast called for head winds and we needed time in port to prepare the boat for the Port Huron-Mackinac race starting in just over three days. The expectation was confirmed when we rounded Bois Blanc Island into a freshening breeze dead on the nose.

The seas rose and the sky lowered apace; by noon we were bashing into a gray wall of leaden waves under leaden clouds, enduring pounding that sent shivers through the boat and drenching spray back to the cockpit. Toward evening we had the good sense to tuck into the lee of Thunder Bay Island to have supper in relative peace. It was there, while we were enjoying spaghetti and chicken in marinara sauce with a bracing cabernet, that a crewmember checked the fuel gauge and announced the level looked too low for the many miles remaining.

“Impossible,” I said. I had calculated the amount of fuel put in the tank myself. And I had done it carefully, or so I thought, not just to ensure that we had enough, but that we didn’t have too much. At seven pounds per gallon, diesel oil is not something you want to carry in excess during a race.

But I went below and recalculated and, sure enough, my math was fuzzy. The new math showed that we would run out of fuel long before reaching our destination. A look at the chart monitor added more bad news: There was no port deep enough for our boat within reach.

We raised the mainsail in the hope we’d get a boost motorsailing and left our cozy lee. But there would be no boost. The once punishing southerly began to peter out and soon was just a memory, leaving us chugging into leftover seas at reduced r.p.m. making slow progress toward a point hours from our destination where the engine would inevitably wheeze and die.

When I came on deck with a crewmate for the midnight watch, there was no wind except what the boat made with its forward progress at the anemic rate of 5 knots; the water was almost flat. But soon we noticed some activity on the instruments. The true wind numbers were rising in small increments. The true wind direction was steady from just forward of the beam.

I stopped the engine. We sat still for a moment, drinking in the lovely silence. Then we began to notice things. The night was surprisingly bright, a small moon behind a dappling of clouds, thick patches of stars. The once uniformly smooth surface of the water was scratched here and there by cat’s paws. Aloft, telltales were twitching on the mainsail leech, the Winddex was settling down, pointing at a reaching angle. And then we could feel it; from the subtlest stimuli, we could sense it—the breeze was coming.

I wrestled the light No.1 genoa, a sail normally not to be used for anything but racing, on deck. We set it and trimmed it with a barberhauler, then eased the main and added a bit of vang. The breeze applauded the conversion of our boat back to a sailing vessel with a moderate burst of velocity. The boat surged forward smoothly like a thoroughbred liberated from its stall.

We sat on the windward cockpit seats, feet braced against the gentle heeling, and observed the world around us in a state that may have approached awe. We listened to the silence we created by killing the engine, improved by the music of the bow wave and the hiss and gurgle of the wake. We studied the sky evolving with the arrival and departure of clouds, the horizon with the occasional lights of a freighter and the water, still quite smooth with the wind mainly aloft. With the autopilot steering effortlessly, we took delicious satisfaction in looking at the speed-over-ground readout, seeing that we were making 8 to 9 knots, on the rhumbline, without the expenditure of a single drop of the boat’s scarce petroleum or the production of a single harsh decibel. We could easily have slept in turns, but we didn’t, unwilling to miss a second of this gorgeous watch.

I had been embarrassed by my flubbing of the fuel computation, but by the time I turned in I was congratulating myself on our good fortune. Desensitized by the insistent drone of the diesel, we would never have been aware of the opportunity to experience this halcyon night of sailing were it not for my mistake.

The breeze took us almost to the tower marking the start of the long channel into Port Huron. We powered the rest of the way, happy to consume
some of what was now a surplus
of fuel.

In my dream boat, I still want that big engine, but after the lesson of the night breeze, I will know when to turn it off. I hope that part isn’t just a fantasy.