Waypoints Changing?

[Shad_Master]

I was watching an episode of Bass Pros the other evening where Edwin Evers was setting out brush piles. I though I heard him say that using GPS waypoints was not alway accurate because the government might not be releasing them or something like that. Haven't had time to go back and rewatch this, but wondered if anyone knows what he meant by that.

[bigbassctchr101]

At one point in time, GPS coordinates were only good up to about 30 ft. Once that was changed, I think it got down to about 3 ft. But I couldn't swear on that. Maybe thats what he meant?

[Aluma-Bass]

signal is key too....if you have weak gps signal i notice its not as accurate when locating a way-point. Sometimes i will reset and it will search for a stronger signal which will get you alot closer. My handheld gps will tell me how accurate its signal is...like it will say with in 20-30ft accuracy or down to 5ft accuracy if im getting good signal.

[Jig Man]

Some say that it isn't so but a guy who spent 35 years in the government working with their gps equipment told me that they vary the accuracy that you are allowed to have from time to time so on a bad accuracy day one will have problems.

What ever it is, I know that mine doesn't work the same from one trip to another getting on wpts in open water.

[james 14]

I'm not sure what he meant about the gov't releasing the waypoints but basically took it to mean that GPS is not the best thing in the world for trying to find something as small as a brushpile. You either need to have something definite on shore to line up with or find the spot on your depth finder each time. I prefer to find it on my depth finder and then throw out a marker buoy. That's about the most exact way to do it.

[flipin4bass]

Some say that it isn't so but a guy who spent 35 years in the government working with their gps equipment told me that they vary the accuracy that you are allowed to have from time to time so on a bad accuracy day one will have problems.

What ever it is, I know that mine doesn't work the same from one trip to another getting on wpts in open water.

That guy is right, sort of. I worked in surveying and with GPS systems in the military up until I retired in the 90s. Back then signals had 100 meter errors programed into the signal and unless you had military gps that removed these errors, your error on the ground could be 50x50. (50 easting and 50 northing) I don't think these errors are anything like that today as more and more civilian agencies have become dependent on gps. (police, firefighters, etc.) However, they still exist and for obvious reasons. We can't have a bunch of anglers out there with the capability to target critical sites, like rock piles and submerged trees.

[lmoore]

Satellite availability varies by day also. I went to school as a Civil Engineer, and during one of my internships we only surveyed on Wednesdays. There was a small group of satellites that were only available for our use on Wednesday of every week, so we'd get much better accuracy on that day. There might be similiar things going on with boat GPS units.

[J Francho]

Your waypoints don't change. How accurate the GPS interprets you actual position is affected by many things. Some units are more accurate by using more satellite signals at once, if available.

[Wayne P.]

The spec accuracy of modern GPS units is 3 meters for the best models. Not only are GPS satellites used for position, the WAAS satellites are used. The WAAS satellites are near the equator and are positioned there for airplane navigation. I think there is another satellite system used too. Another one that was used and may be still is the radio antenna type along the coast.

Selective Availability was turned off by order of Pres. Clinton in 2000.

http://www.gps.gov/s...dernization/sa/

If Edwin Evers has one of the other brands of GPS equipment he may experience position errors that may make returning to waypoints more difficult.

I regularly get 2' EPE with my units and so do many others with the same equipment. I was assisting with a SAR operation recently and found a possible return. I saved a waypoint and returned to the base of operation to show those in charge, I led a dive boat back to the location, dropped a marker exactly on top of it and a diver went straight down to identify the return that was negative for the subject of the search.

[Wayne P.]

This is from an owner in Missouri with the same brand:

[Chattahoochee]

I didn't see this show, but could he have also meant that sometimes the brush piles themselves move? I know i took a bunch of oak limbs and chained and weighted them with cinder blocks. I marked them when i put them out. 3 Weeks later they had been moved somewhat by the current of the creek channel they were in. Making my waypoint wrong. Just a thought.