Dave Martindale wrote:
"John Bell" writes:

The GPS itself will indicate the amount to turn in order to reach the
correct heading. COURSE or DTK (synonyms) will change along the
route as a reflection of great circle effects. Likewise, the
BEARING will also change for great circle. While what you said is
correct, a good way of staying on course is to compare TRACK to
BEARING or keep TURN to zero. This makes it easier to find the
heading that keeps the vehicle along the centerline of the path.

I haven't heard of a GPS receiver that will tell you what heading to
fly
or sail to compensate for wind or current. A GPS-only unit has no way
of knowing what your current heading is in the first place. It can
tell
you how much to turn to align your heading with the desired course,
but that assumes no wind or current. In practice, you'll have to make
adjustments to that heading, while watching the cross-track error.

We use GPS receivers in our gliders, and most of them can find the wind
direction and speed automatically by detecting that you have made a full 360
degree turn (happens often for gliders when searching for thermals), and
analysing the 360 degree turn you have made for drift direction and speed.

And I'm certain that the information is used to display a wind-corrected
heading.

We use Pocket-Nav http://www.cambridge-aero.com/pocketNAV.htm and others.

/Mogens