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this may be a silly question, but as they say the only bad question....
Anyway, I have a handheld garmin gps 72 that is supposedly waas enabled. When I use it on my kayak and look at distance, speed, track etc. it seems to be perfect. However, when I put it in my boat and try to find a small reef, the compass starts going nuts from about 150 feet out. I try and use a combination of bottom machine and the force to fid the reef.
I heard someone say that you need to be moving to get an accurate fix, but I don't think everyone hits their spots at 20 knots and throws a marker.
Is my problem an entry level unit, operator error or combination?
It's a 23 foot center console that is "topless". I have the unit sitting in the marine mount bracket just ahead of the steering wheel. It is powered with the adapter.
The GPS does NOT need to be moving to get a good fix.* Only needs a clear, consistent view of the sky that is sufficient to "see" three of the satellites (more is better).
If you are moving slowly, the unit is very likely to give inaccurate information on speed and track.* This is due to the relationship between average error between fixes and distance moved between fixes.* The slower you are going, the greater the likely error in speed and track.* Some GPS units have*a "Track Smoothing" feature that can compensate somewhat for this problem.
The compass rose on a GPS 76 figures out which direction you are going by using your position delta. You have to be moving for it to read correctly.
Note, however, that you don't have to be moving quickly; but you *do* have to be moving.
When I'm trying to drop the hook on a particular site, I get to within 200 feet or so, then cut the throttle back to idle, and idle up to the site. When the distance to waypoint reads anything under 20 feet, I give a quick rev of reverse power, and drop the hook.
It helps to approach the waypoint from directly downwind, otherwise you'll drift off while the anchor drops.
I get to within 200 feet just fine; I'm guessing that as I idle up to the spot the unit should not keep saying "distance to point" 130 feet
(+/-) in another direction? I navigate with the gps' compass. Should I try another screen? I think the 72 is the same as the 76 except I only have 1 mb of memory. Correct?
The below link is to a site of a bunch of weirdo's that actually made a hobby out of hiding little trinkets in tupperware containers all over the planet and then searching for them with a handheld GPS.* I think they have too much time on there hands but then again, what do they think of us searching around the water trying to find and catch fish we can't see!!
Anywho, they have alot of knowlege on how to find an exact lat/long GPS location on land.* You can use alot of the same techniques on the water.
Even though you have a Garmin GPS that can use WAAS differentials does not necessarily mean that it is using them. Go into the setup menu and confirm that WAAS is actually user- enabled as I believe the manual states is necessary ( that may be 1st time or each battery change?) . Also, check to see if that Garmin h/h has user ability to reduce the waypoint proximity circle so you can make a closer approsch to the WP before the GPS goes back to position mode from nav. . As noted above you still need to be slightly moving for the nav or compass function to work well.Finally, make sure any compass function is user-calibrated according to the manual at each battery change at least & maybe each startup.
*You may want to try the plotter screen. Once you get within a 100 feet or so, switch to the plotter screen and watch your progress to the waypoint graphically. It takes a little getting used to, but, I find it particularly useful.
The compass rose on a GPS 76 figures out which direction you are going by using your position delta. You have to be moving for it to read correctly.
Note, however, that you don't have to be moving quickly; but you *do* have to be moving.
When I'm trying to drop the hook on a particular site, I get to within 200 feet or so, then cut the throttle back to idle, and idle up to the site. When the distance to waypoint reads anything under 20 feet, I give a quick rev of reverse power, and drop the hook.
It helps to approach the waypoint from directly downwind, otherwise you'll drift off while the anchor drops.
HTH,
jky
Actually, not all units have to be moving for the compass to work. The Map 76S had an electronic compass that work while moving or standing still. I have better luck finding structure with my MAP 76S than with fixed mount units! WAAS should be accurate to 3 meters (10') Also, there is a software update that came out in Feb 05 for your Map 72.
Update---> http://www.garmin.com/support/collec...t=010-00309-00
Cat O Lies - 3/31/2005 7:12 AM
Actually, not all units have to be moving for the compass to work. The Map 76S had an electronic compass that work while moving or standing still.
The 72 (which is what go4ecu was asking about) does not have an electronic compass.
The steering rose (better term for it) on his unit uses the differential between samples to determine where you are going vs. where you want to go.
No difference between samples means the unit has no clue as to how you should steer to get there, only how far you need to travel to get there.
Yes, some units do come with an electronic compass now. AFAIK, they are susceptible to the same influences that cause errors on mag compasses. Solution looking for a problem, IMO [Geez, I'm starting to sound like my Dad used to. That's scary.] Then again, I've never used one.
cat o I just ran the update. we'll see how it goes. I'll also try using the plotter screen as i get closer. if none of that works, i'll pony up for newer unit. really hope not to though.
gps accuracy help 
I'll also try using the plotter screen as i get closer. if none of that works, i'll pony up for newer unit. really hope not to though.
