On Fri, 13 Feb 2009 12:11:49 -0600, cavelamb
wrote:

All the GPS shows is course to destination.

Based on that, how does one determine set and drift?

The wiseass answer is that that is what air navigation slide rules are
for.

Pilots do it at 600 mph with all the gear on their lap, or at least
they used to. When I learned to fly the navaid was VOR, which gave you
the heading and distance from a station, and you set it and kept the
needle centered. You fles over the stations rather than the shortest
distance. The gear learned to read two stations and give you lat long
and other things. Called that area nav. Very expensive and forgotten,
like Decca. You could get sextant size fixes, half a mile. In good
weather, DR would get you within sight of the destination after 300
miles without a fix, once you had the wind figured.

Who remembers Consol and Consolan. You listened to a tone and got a
line of position. All you needed was a short wave radio. That **** is
long gone and nearly forgotten. I have not thought of either for
decades.

Set and drift? Why would you care, when there is no reason to know.
When you can just set the true course and keep the needle centered.
GPS gives you something to steer by, not a starting point for
calculation.. You center the needle and and go straight there. In a
fast powerboat speed and heading changes show up quickly. Did I
mention that it will display a speedometer.What it does is store fixes
and calculate the speed and course. It will show track on a lat long
grid.Assuming you have the features of a ten year old handheld.
I bought a handheld about ten years ago that did everything damn near.
If it could cook Id have married it. Could have a
compass dial. Did maps.Had a 3x3 screen with red lighting. Took 8 AA
or the lighter socket. While many electronics run on anything from 6
to 36, it is in fact, 12 V. Eats batteries. You could remove the tilt
adjustable antenna and use a remote cable. Eagle, the freshwater
fishfinder makers.

I get the impression you have never been near a GPS.

If all they did was lat long to sextant accuracy, they would still
sell.

Casady