Glenn Ashmore wrote:
"krj" wrote in message
.. .

The Raymarine ST60 wind instrument uses the masthead windvane and
anamometer for apparent wind. It uses the SOW from the Tridata paddle
wheel and the COG from the autopilot to compute true wind.
No gps input needed.
krj



That will not account for set and drift. It will give you true wind
relative to the boat but not true wind. relative to the mark you are trying
to get to.

Works OK for me since I use waypoints 20 to 50 miles apart instead of marks.
krj

A waypoint is the same as a mark. It does not move with the current.
Using only the speed through the water a cross set with a couple of knot
drift in light wind can create a huge error.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"krj" wrote

Works OK for me since I use waypoints 20 to 50 miles apart instead of
marks.
krj