Thursday, June 26, 2014

Double Whoops

Porter Bay, VT

I'm single handing today.  Libby and Victoria are gardening at Jen's house.   Me? I'm just hanging out in one of my favorite places -- Porter Bay.  Porter Bay is where we sat out hurricane Irene.  It is pristine, and mostly uninhabited.  I'm the only person around.   There is lots of wildlife.  The sky is blue, the sun is warm.  Life is good.

One imagines travel by boat and by air as simple straight lines.  Bumps, loops, wiggles, and jerks are not expected in the trajectory.  When they do it is a case of Whoops.  Below are two such cases from recent experience.

Whoops number 1: (below) This screen shot was taken from our GPS in Abemarle Sound, in North Carolina.  What do you suppose caused that S-shaped course deviation?   Well, I was on watch as we motored across the sound.  Then I noticed that our speed had suddenly dropped from 5.5 knots to 4.0 knots.  "Uh Oh," I thought, "the last time that happened we had snagged a lobster trap in The Gulf of Mexico and dragged it for miles.  I'll bet we snagged a crab trap and were dragging it."  Remedy number 1, I put the engine in reverse and backed at full speed trying to dislodge the trap.  Then back to forward to test the result.  No change.   I sighed.  Then I stripped (nobody was around), put on my mask and snorkel, grabbed a knife and jumped overboard to cut loose the trap.   The water was dark brown so nothing could be seen from the surface.  When I got down there, I found nothing.  There was no trap.

The explanation turned out to be simple tidal currents.  I am accusomed to thinking that there are no tides on the inland waters of North Carolina, but this spot is an exception.  A 1.5 knot ebb tide flowed south and west of Roanoke Island, and that's what slowed us.  By the time I took the screen shot 5 minutes later, the speed was 4.35, and 20 minutes later it was the normal 5.5 knots.

Whoops number 2: (below) We did not do the canals last year, an I forgot some of the things I had learned before about mast stepping/unstepping, and navigating the canals.  One such thing is navigating under the many low bridges on the Erie Canal on autopilot.  You see, our autopilot steers by compass, and these old bridges are low and magnetized.   I forgot to put the autopilot on manual as we passed under the bridge and the autopilot went crazy.  That's what caused the violent and wild  dipsy doodle in the magenta track line seen below.  (look carefully, the dipsy doodle is right on top of the "73 44" text marking longitude.  The parallel wide yellow line is the bridge.) Fortunately, I did not hit any other vessels or anything on shore.

 I took the screen shot two days later as we were retracing out steps. That is why it shows us pointing toward the dipsy doodle rather than away from it.

Both incidents are examples of why a real human must remain alert on watch all the time.  Things happen.

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