On Mon, 19 Jan 2004 11:04:35 -0500, "Gary Warner"
wrote:
We bought the handheld Garmin 72 for our little 22 footer. We won't be
doing much if any long distance navigation, but just knowing our position
and just "playing" with the thing should be fun. Goofing around with it
inside (while it's cold and snowy outside) a few questions come to mind.
-- Lets say you are out in open ocean and heading for a waypoint that
it programmed into the unit. If everything was calm, no wind and no
current, all you have to do it point the arrow at the waypoint. But what
if there is a current and/or wind? Just pointing the boat toward the
waypoint might not take you on a straight course to the destination. You
would need to steer a different course to get the desired outcome. So:
Can this GPS (or others) help figure what course you need to steer?
Almost all of the can. It's called "course" mode instead of "bearing"
mode. In bearing mode, the pointer always points to the target. If you
stray off course, the bearing will change and point to the target. But
that's not really what you want since if you have something driving you
off course like wind and current, your path to the target will sort of
spiral in if you follow the moving bearing.
With course mode, the GPS always points from the start of the leg to the
end of the leg and generally shows a CDI, or course deviation indicator,
which shows how far off course you are. If you steer to keep the CDI
small, you will travel in a straight line from your start to end point.
Many also have a "steer" function that tells you how much to turn left
or right to stay on course.
-- I see there is a "Highway" screen that shows a "road" that one
might follow. Seems that may be the correct screen to do what I'm
thinking, but I can't quite figure out it's use.
If the highway screen is anything like the one on my old 45xl, that's a
good one to use. It shows your course and how far off course you are.
Just stay down the middle of the highway and you'll travel the shortest
path, which is the straight line.
Well, probably all this will become clearer when we can actually use
it ON the boat.
Oh, any good books out there telling how to use a GPS (not a manual
for a particual unit, but a general 'how-to' book of ideas and uses?
Everything you ever wanted to know about GPS, from basic "how to" to
detailed info about how GPS works is available at:
http://www.gpsinformation.net/
Steve