WAAS Enabled GPS ~ How accurate?

[Red]

(I’m looking at the eTrex Venture HC, (in fact I’ve got a post looking for one over in the gear buy / sell section), I need something to accurately map an outdoors guidebook with.)

Any thoughts or suggestions would be much appreciated.

Thanks,

‘Red’

[Arthur Bowie]

without WAAS my etrex Legend usually reports a circle of accuracy-or whatever the term is- of something like 15 to 30 feet.

With WASS it reports uncertainty circle of 8 to 12 feet and may be a little slower to lock in.

Most of the time the only errors I notice in either mode have to do with the maps, typically back roads aren't mapped as accurace as GPS so it may look like I'm driving off one side of the road or are several feet off a turn or intersection.

Everything I do paddling, hunting, or hiking GPS is way more accurate than needed. Worst case has been trying to find the hunting truck, with GPS on and working, never a problem to find the truck.

However if you are landing an aircraft in minimums of say 200' ceiling and 1/2 mile, then the WAAS accuracy is important at that one time in the flight.

Also, the accuracy from consumer handhelds are not where near what is needed for surveying. I had a discussion with a young surveyor not long ago and he discussed accuracy issues. In particular he had tales of land owner trying to do his own survey with handheld GPS and created several problems. Accuracy is good enough to assist locating a marker or line, but about factor of 100+ off from being good enough to set same.

[Red]

Arthur ~ Thank you for your reply and input ~ I appreciate the help.

Best,

‘Red’

[Clif]

Sounds to me like you need more of a unit. I have a legend. Great for markiing put ins, crossroads, etc... For serious mapping tho, I dunno. It would work if you're on a budget.

Do a bit of geocaching. Kids love it. Hunting small boxes or even things small as a 35mm film can. You get the coordinates and off you go. My legend has been 30-40 feet off at times. Dead on other times. Of course there is no garauntee the coords provided were totally accurate. Like say the person putting the coords in is 15 feet off. Then I am 15 feet off..... 30 feet. Finding roads or a car tho how accurate should you be. Mine also shows me off the road by some distance at times. In the hills and high pines seem to agitate it more.

Waited for a newer more precise unit. Then maybe these would drop in price but that ain't how they do it. They add other features and memory and keep them in the same price range. Some newer units give better readings but they are a bit more $$.

[Red]

Hi Clif ~ thank you for your reply ~ the most important considerations for me, (before price), would be accuracy, handheld, color LCD, pc interface, topos.

Was looking at the Garmin 60 CSx for this application, however, the smart money says that all of these units, (eTrex / CSx / et al), will go by the wayside pretty soon with the fast approaching next generation GPS applications ~ so I don’t want to throw away the money on an overkill GPS ~ when new GPS stuff is around the bend.

(I still have bad feelings about the OnStar analog to digital switch over.)

But any thoughts about specific units would be much appreciated.

‘Red’

[Dannyboy]

How are ya Arthur.

Yeah, my GPS has an accuracy of +- 2 hundreths of a foot. But you don't want to have to wait for one like that to initialize every time you want to capture a point. (or pay $52,000 for the opportunity) Point in fact is that usually the more accuracy you require or your equipment is capable of, the more complicated it is and the more time it takes to get a result.

Check out the Trimble GeoXH (my next playpretty). It's only about $5,000 but it's accurate to within 3 to 5 feet, what they call "mapping grade" GPS. However, you can load all the topos, aerials, etc. that you want for background maps. And the software is a lot more friendly for collecting so-called attribute data. They do sell some cheaper versions and you can still get a good Ebay deal on a GeoExplorer 3 if you don't mind giving up a color display. Hopefully I'll have a GeoXH this summer if anyone wants to see it in action mapping Cadron creek. I have access to a large-format plotter (printer) and I'm planning on creating some dandy maps over the next two years of my favorite runs.

Sorry I got off topic, I'm kind of a GPS/mapping dork. Good topic though, as I'm shopping for a new recreational-grade to replace my ancient Garmin 12XL.