I would like to thank everyone that's responded in my original post, but I don't think I asked the correct question.

Which actual units are people using? Name, model / serial number, etc etc? I have specs to run with but there are too many models to choose from. I'd like to narrow down my choices to those that my fellow peers actually have experience with.

I have a few different reations to your last post. The negative part--"just tell me what to buy so I can figure out how to use a GPS and advertise my self as having the "best equipment ..." leaves me quite cold. The positive part--is that you have raised questions about the use of GPS in wetland delineations and how they should be used in jurisdictional delineations. I hope that thread can be continued with respect to the positive part-the appropriate use of GPS in wetland delineations and the scale at which they should be used.

There is no "best model" to buy. That does not exist. I suggest that you ask the wetland group for their expereince with GPS rather than a best model to buy.

Leslie -
I don't wish to continue this in a public forum and clutter up the board, but I feel I have to post a reply to your comments.

I don't believe you read either of my original questions correctly, or you have grossly misinterpreted them. "Which actual units are people using? Name, model / serial number, etc etc? I have specs to run with but there are too many models to choose from. I'd like to narrow down my choices to those that my fellow peers actually have experience with."

Nowhere in that question is a "negative part", IMO. I have read that delineators use GPS technology to map their lines - but I'm not sure if people are using handheld units, backpack units, etc etc. There are subtle, but important, differences between the two types, and I'd like to know what the community's experience has been. Please take care not to confuse the "issue" here.

I didn't read anything negetive into your request. There are definite differences in GPS units. I learned this through renting diffent ones before buying. I tried a handheld it was a magellen that was suppose to be mapping grade. It was very simple to use and only about $1,800, but not acurate enough for mapping wetlands. I ended up renting a Trimble pathfinder and re-surveying. I also rented a TDS solo GPS backpack unit many times, but thought that the accuracy was not as good and also overall I thought the Trimble Pathfinder had a lot more practical field features in terms of a more durable set up (ie cords, connections etc.) It comes with a very nice user friendly program for post data processing. I don't want this to read as a paid endorsement for Trimble. There are probably a lot of other good backpack units out there. Another key is learning how to use it. I've learned that it is important to adjust the settings prior to using the instrument so you are collecting better data. For example the settings can be adjusted to collect only data with a minimum of 6 satellites and PDOP of 6 or less. Also you can look at your data with the better programs and throw out the readings that are way off anbd with experience these are easy to pick out.

I think the COE memo was good guidance because there is a difference in GPS data collection both in the instrument and the operator and accuracy is very important esp when it comes to the location of areas that are going to be avoided.

The best option may be for you to rent some different systems and compare on a particular site that has been previously surveyed by registered surveyors. That is what I did. You would also find out the system that you personnaly like and how it works before you make a big purchase.

Thanks for the ideas Chris!

I didn't consider renting - though a little time consuming, it would definitely help narrow down our choices

I use the high-end (non-professional) Garmin Etrex Vista C. It is easy to use, stores a lot of data, but eats batteries like cheezepuffs if you don't turn off the electronic compass. It is amateur grade, not professional. The accompanying topo map software needs some improvement, like inclusion of 7.5 min. maps.

But, I only use GPS to create presentation maps for reports. I leave the surveying and mapping of wetland limits to professional surveyors. Most of my work is for civil engineering firms who have surveying crews. I let the surveyors shoot my flags and give me an updated survey map with calculated acreages.

I think you misunderstood. There were many good technical criteria on your previous post. I do tend to get frustrated with the approach of "don't give me any discussion, just give me the answer".

The problem is that, with any question or issue, your answer depends upon how you frame the question. Trimble, Geo explorer and Garmin are all good units. Which one you choose depends on the following factors:

1. What are you going to use the delineation for and what resolution do you need to meet 404 permit needs as well as future planning needs.
2. Who is going to develop the wetland maps--someone in your company, an outside contractor? Will the maps be imported into GIS or AutoCAD and is the software with the unit compatible between the 2 programs?.
3. Do you work in a remote area, in which the number of satellites you can receive on a given day can affect your accuracy?

Let me provide you with one of a few concrete examples that are why I resist the "name brand" approach and why I ask these questions:

Example #1: A contractor used a backpack GPS unit (name brand) to survey a wetland boundary. The boundary was imported into AutoCAD and used for planning. The objective was to completely avoid the wetland. The plans were developed over the winter and in the spring, were staked out using a more accurate survey method. OOPS-the building which had been totally designed to avoid the wetland now encroached on it by 10 feet. Why? Survey and map transfer "errors". In using the term error I don't mean that anyone personally erred, it is used in a statistical sense in that some errors in the original survey were propagated throughout the design process.

Example #2: A contractor used a hand held GPS unit (name brand) to survey a proposed mitigation area. Accuracy was supposedly within 2-3 feet. Resurvey for mitigation purposes using a unit that was verified for 0.1 accuracy or less showed a very different wetland area.

Bottom line to me is that both hand-held Trimble and Geo Explorer are suitable for delineations, but that the overall accuracy of the unit needs to be reported, as well as the accuracy at the time of the mapping, as they are 2 different items.

Trimble Geo XT, is is advertised sub-meter accurate. We achieve that with the correct setting and data management. One problem the people have with GPS units being "off" is projection problems within GIS and CADD software. (IE Nad83 and Nad27). We use the GEO XT and I rave over it. Just make sure that you are using a corrected signal (DGPS or WAAS) and your conversion over to the desired format (GIS or CADD) is right. Hope this helps