So during a
passage race off shore this weekend we were in really bad haze for a while out of site of the shores which were only 5 miles away or so. We were becalmed although I knew we had about 1/2
knot boat speed as we were making a tiny wake. The
skipper started turning the
boat back and forth and with the tiny breaze we had eventually got us stuck in irons. He then started making noises about "the bloody"
gps being wrong and which way to go etc...
I finally went to look and the boat was headed 270 on the
compass, boat speed was 1.8 knots but the "lead line" projection of course was leading out at 90 degrees i.e. off the bow of the little icon which was also headed 90.
I started laughing at the
skipper which is not a good thing to do 5 miles off shore but then had to explain to him why the
gps was "all screwed up."
We were heading 270 mag, but the gps doesn't know heading. It only knows direction. It aligned the little boat icon on 90 @ 1.8 knots because that is where the boat was going in the 2+
knot current.
He has a speed log but it is uncalibrated. It reads about 1 knot when we are doing 4+ gps speed. I have asked him a couple of times to go out and calibrate it and took the opportunity to remind him again why it is good to have boat speed available.