Terrible Trestles, Towering Thermals and More

The Erie Canal, Near Clay NY
43 04.48 N 076 51.61 W


I'm lazy.  My least favorite chore on the boat is actually steering it.  Therefore, even on the canal I like to use the electronic tiller pilot.  (Libby doesn't).   Most of the time it works fine, but I found an exception.  The NY canals are crossed by hundreds of highway bridges and railroad trestles.  Most of them are only 15-20 feet above the water.  The problem is that many of the older ones have become magnetized.  When we pass under a magnetized bridge the tiller pilot goes crazy.  I have to grab control immediately to keep it from steering us up onto the bank.

A Terrible Trestle 

Actually, the magnetized bridges excite the engineer in me.  Our Ritchie card compass sees almost no deviation because of the bridges while the flux gate electronic compass does.  Why is that?  Well, using the Tricorder app in my Driod I can monitor the magnetic field in three directions.  I see that the biggest disturbance is in the Z axis,  normal to the surface.   I hypothesize two things.  (1) The card compass is better designed to be sensitive to the horizontal component of the magnetic field. (2) The flux gate is tiny.  It works on small signals and it is more sensitive to noise.     By the way, using the Tricorder I am able to see that these bridges leave a magnetic shadow extending a hundred meters or so.


Every day and night we note sights and sounds that remind us that we are in the Northeast, not the Southeast.   Yesterday I watched as thermal bubbles lifting from the ground create and grow spectacular cumulus clouds.   Back when I was flying gliders, that was a sign of a splendid soaring day.


On the ground we hear crickets at night; sometimes peepers.  Yesterday I heard the annoying sound of a flock of crows.  Been a long time since I heard that.   The air at this time of year is filled with cotton-like wisps that float around.   Is that cottonwood trees?  We forget.  I'll bet some blog reader will tell us.  Later in the season we'll see the one-winged helicopter seeds falling from maple trees.   


This morning we saw a stand of magnificent reeds in the Montezuma swamp.  They were 8.5 feet tall.  I can't recall ever seeing such tall and proud reeds before.   Montezuma, is one of four swamps we cruise through.  The others are the Pee Dee Swamp, The Everglades and (well known to blog readers) The Great Dismal Swamp.


I'm afraid that the Montezuma Swamp is no longer as extensive as we imagine.  It is subject to the veneer effect in the extreme.  Last night we stayed in a lovely natural setting at lock 25.  We tied up in the cool shade of the bridge on a warm afternoon.  I checked it with Google Earth.  From the two pictures you can see the contrast between the canal environment and the surroundings.  The first picture zooms in and the second zooms out. Sigh, once again we see evidence that this planet is populated to excess by people.