View Full Version : Questions about GPS acurracy
ck85abc
12-10-2002, 04:00 PM
I was reading on GPS systems and it says that the department of defence limites the precision of GPS to 20-40 meters. When it comes to walleye fishing and you find a whole that you go through with spinners and catch fish you want to be right on the nose, even 3 meters off can mean no fish. So how exactly is follow a trail really going to help you much? I can and do follow a trail that I made and cought fish by sight to within 20-40 meters.
Also, say you are maping a channel up the reservor so you can get further north were the fish are bitting, but the channel is only 5 meters wide. You are going to run into ground with that precision.
Or are the alot more precise than what the DOD(department of defence) says?
BlackSilver
12-10-2002, 04:34 PM
The current units with WAAS are generally accurate to within a boat length.
Use your GPS to get you there, then fish with your graph. At drifting/trolling speeds the GPS is way too slow for any kind of precision fishing.
Walk softly and carry a big fish.
Hans/MN
--
"Many go fishing all their lives without knowing that it is
not fish they are after." - H.D. Thoreau
ck85abc
12-10-2002, 04:38 PM
I have noticed that were I fish fish don't normally stay in the same spot from day 1 to day 2. So using gps to get me there does not do much. My primary reason for getting one was to follow a exact rought at slow speeds. If I can't do that I really see no reason for getting one. I read up on the WAAS thing and a boat legth would be alot better than 20-40 meters, but I would like 1-2 meters. I think mabey if I wait 2-4 years there might have systems out with that acurracy.
retire55
12-10-2002, 05:35 PM
ck85abc:
You might find this article on GPS WAAS accuracy interesting
http://users.erols.com/dlwilson/gpswaas.htm
The defense department limitation was done away with several years ago. My GPS routinely gets me within 6 feet of a waypoint. It did so three days ago when I was searching for a property marker in the woods that I'd marked a couple years ago. GPS said 6 feet and the marker was three feet away. Close enough for me! I don't have WAAS. I find it even more accurate in the boat where you don't have trees blocking your signal.
-Roy
Dave in Walker
12-10-2002, 09:32 PM
one thing to remember, you should remark all your old spots, those were marked when SA was turned on,thus you could have errors now. Remark all old spots
When I first got my first GPS several years ago, I set my GPS by my mail box, for a couple of hours, and took the average reading and set in a waypoint.
Over the years, as SA has been turned on and off, as wass has become available, etc. I have used the mail box waypoint as a reference.
Generally, when coming home from a fishing trip, I have the gps mounted on the dash of my tow vehicle.
I generally have the arrival alarm on, so that I know when I get to within .01 mile.
Over the years, the arrival alarm goes on within about 50 feet - on average.
Then, If I navigate to my mail box, I am generally within a 6 foot circle of the mail box. In years past, there were a few instances of where the box, would show up as being about 75-80 feet off; and once was 300 feet off. But, in the last year, I have never seen it off more than about 4-5 feet.
This distance, has certainly been fine for me to find the locations that I need to find the fish that I catch.
Take care
REW
The EyeJacker
12-11-2002, 10:20 AM
Thanks,This confirms what I have been thinking all along! :)
Jack
T-Mac
12-11-2002, 12:29 PM
I noticed I am not being shown "running" alongside the river up on shore on my map as much as I used to be.
My WAAS sure goes on and off a lot. I mean A LOT!. Anybody have any ideas on that?
Thanks in advance.
Over the past year when zoomed in correctly, I have found the WAAS technology to be off up to 14-15 feet but that's a significant improvement. It's meant more as a navagational tool to get you in the vacinities or keep you in the vacinities vs. keeping you on an exact line or spot.
It has it's applications, however if your looking for the spot on the spot...you gotta use your sonar.
Good luck,
TJ
7 meters = 22.97 feet
My X-15 w/WAAS has been giving me a consistent 13'-16' accuracy. Not bad.
Fishing 21
12-11-2002, 03:58 PM
I ran a X-15 with WAAS last season and noticed major improvment over standard GPS. My accuracy varied from 10-30 feet an average. Sometimes more, Sometimes less, overall I am very impressed. I run mainly on the Canadian Shield Lakes and experienced some locking in and out. Treelines make all the difference. Hopefully this will improve as more equipment is installed.