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How to Navigate in Fog with Your Boat's Electronics

Here Be Fog

Join us as we “press and hold” our way through
a gnarly Down East transit.

Boat in fog

Back in the early 1980s, cruising in the Gulf of Maine could be awfully stressful. One time we were bound for Boothbay Harbor when fog rolled in so thick we could not see 50 feet in front of us. Our navigational arsenal consisted of a chart, compass, wristwatch, and the uncertain knowledge of our position at the moment of blindness. Oh, and I almost forgot, potato chips. 

In order to advance our dead reckoning course line accurately we needed to know our speed. Crew in the bow would throw a chip in the water and holler. Crew in the stern would time the chip as it passed by. We’d throw five chips. We’d discard the high and low times and average the middle three. 

We’d take that average time and put it into a formula that took into account the length of the boat, 30 feet. From this we would ascertain our speed through the water as a time-distance equation. A marine scientist at the University of New Hampshire had given us a current table for the Gulf of Maine, which in theory would enable us to compute our speed over ground. 

From the Isles of Shoals we set a course for a horn near the approach to Portland Harbor. Our plan was to get close enough to hear that horn then turn to starboard and head down and east for Monhegan Island. The lighthouse on adjacent Manana Island had a horn that could be heard from 5 miles away.

None of this was much fun, but we somehow succeeded, and the very first feature we saw on the entire 24-hour passage was the cliffs of Manana as we poked our way into the rolly little harbor formed by fogbound Manana and Monhegan.

We never would have left the docks had we known the fog was going to be that bad, but fog is prevalent in July, and we were four guys on vacation. We weren’t going to stay put just because there might be fog.

Navigating in fog

Fast-forward 30 years. One of the perks of magazine writing is that every once in a while someone tosses you the keys to a new boat and lets you take her for a spin. In our case she was a Cutwater 28 and the “spin” was a 250-mile cruise from Bangor, Maine, to Boston. “Perfect,” I told my crew. “Maine in September means cool nights and clear days. The fog is worst in July.”

On our third day we awoke to a gray, wet blanket. Friends later told us that the fog that day was the worst of the entire summer. So much for conventional wisdom. We waited until noon, hoping it would burn off, as it had the day before. But the fog remained as thick and unpalatable as Seattle clam chowder.

Down East loop map

Read more adventures from the crew of the Cutwater 28 on the Down East Loop here

Back in the ’80s there was no way we would have left the dock, but those were the days before the miracle of marine electronics had fully unfolded. Both Cutwater and its sister brand Ranger Tugs install suites of Garmin devices onboard, which I was eager to test in fog. I had left New England on my long downhill slide just as GPS was coming on the scene, so my notions about the utility of electronic navigation in fog were only theoretical.

We cast off from the fuel dock at Journey’s End Marina in Rockland around 12:30 and headed to the Muscle Ridge Channel with a hundred feet of visibility.

Down East veterans will tell you: Muscle Ridge is full of gnarly, keel-ripping obstructions, choked with lobster buoys, and filthy with gnarly, hard-charging lobstermen who don’t seem to slow down one bit in zero visibility.

The radar performed very well without my having to attempt any tuning, true to Garmin’s reputation for simplicity of use. Even the smallest vessel, a little wooden sailboat, showed as a return and objects within a couple hundred feet displayed clearly, which is what you want in fog. The MARPA collision avoidance feature displayed on the radar screen exactly the way the AIS collision avoidance feature displayed in plotter mode—the consistency was reassuring.

We knew where we were, we knew what was around us, and we knew speed and direction of other boats. Garmin had given us situational awareness, but there would be little time to react to threats, like the threat of being immobilized by a ball of polypropylene pot warp tangled in our propeller.

Repeating myself: The water was thick with lobster buoys. This is where Garmin’s autopilot really came in handy. It’s got a nifty dodge feature. With a quick press, the port and starboard arrows add or subtract a degree from your heading. But press and hold one of those arrow keys down longer, and the boat begins to turn, and the longer you hold them the more dramatic the turn. Lift your finger off the button, and the boat goes back on course. In little or no visibility, however, this meant going slow. We never went faster than 8 knots in Muscle Ridge Channel.

Fog plays with your mind. It induces claustrophobia. It distorts sight and sound. It feels like you’re wearing that wet blanket I mentioned. When you first catch sight of a buoy—and my crew must have spotted a thousand of them before me—they loom large, magnified by the water content of the atmosphere. Then, of course, you know by the shape that it’s just another pot marker and you press and hold.

As we neared the southern exit of the channel something truly bizarre happened, and maybe a savvy reader can explain it to me, because Google can’t.

It happened when I noticed a lobsterman on the radar, and gave him a blast of the Cutwater’s horn. Then from our starboard side, the mainland side, a siren began blaring very loudly—whoooOOOOP, whoooOOOOP, whoooOOOOP, whoooOOOOP .

What was it? Some new audible aid to navigation, like those new horns that are activated by hailing on a specific VHF frequency? Or was it activated by the sound of my horn blast? Or was it the work of a malevolent fishermen wearing protective headphones.


Check out what upgrades are available to make your system better in poor conditions:

It drove us crazy. We were trying to concentrate on radar and plotter screens, dodging a pot a minute, and now this sound. We couldn’t go any faster to get away from it, and it must have lasted for a half hour. If we could have been certain it was warning us away from a particular ledge, I might have been tempted to run onto it at wide-open throttle to end the torture.

My crew said it best: “It was like being captives in some hellish video game.”

Okay, so nothing has happened over the past decades to make fog fun, but, thanks to systems such as Garmin’s, embarking in dense fog is no longer unthinkable.

Eventually, through Muscongus Bay, the fog thinned out. And by the time we arrived at our destination, we could see objects a mile away. We docked our borrowed Cutwater at Boothbay Harbor Marina, determined to commemorate having dodged a thousand pots and survived audio-torture. We ate a couple of those damn lobsters for dinner.

This article originally appeared in the December 2014 issue of Power & Motoryacht magazine.