NavList:

   

Reply

Rodney,

How does a GPS unit sense the direction a boat is steering?  I have
no clue.  My impression, 5 years after 5 partial days aboard, is that
the unit on the boat I chartered needed to be swung to the boat.  My
analysis, 5 years ago, was that it was swung incorrectly.  I vaguely
recall an error of 15 degrees.  I don't know whether it was a 15
degree error or a 30 degree error, and definitely do not know the
direction.  I meant to say in my previous email that it was _not_ a
true/magnetic issue, but see that I don't have sufficient data now to
resolve that one way or the other.  If the unit needed to be swung to
the boat, nor do you.

I am aware of magnetic/true issues since I usually plot with a
triangle and routinely have to convert course and sight bearings from
one to the other.  I vividly recall a splitting headache of many
years ago from figuring out a course for another guy's fishing boat
compass that was about 90 degrees out, but varying depending upon the
heading, working at night down below over a throbbing engine housing,
with too much alcohol on board, not having thought I'd be called upon
to plot a course.  Fortunately, we had about a mile visibility and
some lights for bearings.

Fred

   

Reply