Thursday, May 31, 2012

Dead Reckoning

None of my boats have ever had electronic navigation equipment so my coastal navigation relies on a tried and true method known as dead reckoning.  The theory is simple: simply draw a line on the chart from where you are to where you want to go (given the geography of the Maine coast, this usually requires several "legs" to avoid obstructions), determine the compass heading and distance of the line, and away you go.  With a reliable compass to keep you on the correct heading, a watch to keep track of elapsed time and some means of measuring (or estimating) your speed, you can pretty much determine where you are at any given time and how long it will take to arrive at your destination.  Of course there are some variables to be taken into account, most notably wind and tide, but basically that's all there is to it.  And when you can see where you are going it's really pretty easy; navigating in dense fog, however, is another matter.

I was reminded of this when the topic of sailing in the fog came up in a recent conversation, and I was reminded of a sailing trip many years ago when my dead reckoning skills were challenged and it took a little bit of good luck to get us to our destination.

The trip from South Freeport to Damariscove Island, where we intended to spend the night, is an easy day's sail.  The first leg is due south for 7 miles or so to clear Eagle Island and Harpswell Neck, then East for about 10 miles to the northern tip of Sequin Island, and Northeast for another 5 or 6 miles to the Gong that marks the entrance to the long, narrow cove on the southern end of Damariscove, where we intended to anchor for the night. It was a trip I had made several times previously so my anxiety level was zero.

The first leg was uneventful as we sailed among the islands that are typical of this part of Casco Bay, but as we approached Eagle Island, which is at the end of the island chain and marks the beginning of open sea, I noticed a haze which reduced visibility to seaward, but it was otherwise still a beautiful sunny day and we proceeded without a care in the world.  And then, as we cleared Eagle and turned to the East, the fog developed - it didn't creep in from offshore as it sometimes does, it just materialized all around us and all of a sudden we couldn't see a freakin' thing.  Bobby, who was sailing with me, became concerned but I assured him there was nothing to worry about as my dead reckoning skills would get us to Damariscove, only 15 miles or so away, with no problems.

Good navigator that I am, I had already calculated the heading and distance to our next waypoint,  Seguin Island, so I just put the tiller over to put us on the proper compass heading, noted the time, and sat back to enjoy the sail on what was still a pretty sunny day - the fog limiting our visibility was strictly at sea level with clear skies overhead.  Seguin rises straight up out of the water with bluff shores, and it showed up just about when I expected it to, although we couldn't see it until we were almost on top of it.  But we were on course and where we were supposed to be, so I turned to the northeast on a course to put us at the entrance to the harbor at Damariscove.  In a couple of hours we would be at anchor and toasting the day with a cocktail.

We sailed on, unable to see a blessed thing, for about what I thought was the right time for the journey and I was still fairly unconcerned, but Bobby, who is a heck of a nice guy but not much of a sailor, was getting pretty anxious about our inability to see more than 100 feet or so, and he started to fret about our situation - he began to worry that we might be "lost" at sea.  Which of sourse we were, but I couldn't let him know that.

Happily, the entrance to the harbor on Damariscove is marked by a gong, which is always a welcome navigational aid when one is navigating in the fog (or at night). So we started listening for the buoy as I knew (hoped) we should be close enough to hear it, and sure enough after a short while a sound from not too far away came through the fog and I pointed the bow toward it.  Bobby was greatly relieved.

When the NavAid came into view I checked the chart to determine the heading to the harbor entrance, when I noticed something was amiss - there were waves breaking behind the buoy and according to the chart they should not have been there.  Bobby's apprehension returned and to be honest I was a little concerned, too.  A quick inspection of the chart sorted things out - we had not arrived at the gong marking the entrance to the harbor but at a bell which marks a ledge a couple of miles south of where we wanted to be.  Apparently the tide ebbing out of Sheepscot's Bay had set us further to the south than I had anticipated.  So no problem, draw a line from where we are to where we want to be, determine the compass heading and distance, and away we go - piece of cake.  Bobby did the only thing he could do under the circumstances - he went to the rail and puked into the water.

The sea breeze out of the south propelled us along and I'm sure we were an impressive sight to those already at anchor as we materialized out of the fog and came into the harbor under full sail. I sent Bobby to the foredeck to get the anchor ready and threaded my way through the crowded harbor - when I can see where I am going, I'm a damned good sailor!  I went up the inlet as far as I dared (it shoals up quickly at the end), came about smartly and headed to an open spot in the anchorage; we coasted to a stop, I told Bobby to put the anchor over, and I dropped the sails.   All's well that ends well.

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