GPS

[grumpie]

has anyone out there ever used a had held GPS and how accurate was it? I'm looking at using it for a class. Please tell me the name brand and model number.
Thanks  grumpie.

[DetectorGuy]

I use a Lowrance H20c and I really like it but I see now that it is discontinued. I have a Lakemaster chip in it that has something like 750 lakes in it that have 3' contours mapped out, and about 200 lakes with 1' contours mapped out. Most of the 10,000 (actually closer to 15,000) lakes in Minnesota are not contour mapped yet on the Lakemaster chip. Every year they add more contour mapped lakes. The Western 1/3 of Lake Superior is mapped in 3' contours I think. As far as accuracy... I think its as tight as any non military GPS units on the market. The trick with any of these is that they will be more accurate on Coordinates that you locked into rather than taking coords from someone else's GPS unit. The reason is that each GPS should be synchronized periodically to survey stakes near where you are using it to lock the Global Positioning Satelites to the general area you are in. These markers (survey stakes) are all over but often overlooked. Using Coords from one GPS on another GPS could put you off 15 feet easily. I like to think that I can get on the same 5' circle every time with mine.

Couple the hand held GPS with Google Earth and the coordinate generating capability that program has and you have a world class navigation system. I have overlaid contour maps from the MN DNR "Lakefinder" site on top of Google Earth images, used the curser to place virtual push pins on proposed depths (say the 15' deep contour line which is usually the weedline) at a spacing of 300' apart and each virtual push pin was a dive site with a coordinate that I could punch in the hand held GPS. No overlap (unless you wanted one) and no missed spots (again unless you wanted one).

My wife is the Vice President of Northern Pines Mounted Search & Rescue and they search for missing people on horseback throughout Western Wisconsin. I taught them what I knew about using hand held GPS for ground searches, and what they could and could not do with a GPS. Its really not too hard to figure them out, just use it a lot and find out what it does.

[arcFlash]

I've used hand held for longer then I can remember.

Your questions really depends on usage. We can assume you mean lakes. In that case a basic unit this is easy to use will get you to any lat/log within 10 feet but you need paper charts or map chips or Google for the lat/log. The GPS is just that, Global Position, not Global Mapping.  If you want maps that's not GPS per say. Some GPS map, some do not. I have an old GPS that is still accurate and easy to use but it gives me a navigation to a point. So I know I'm 8000 feet away from my target and it's bearing is 210 degrees. It doesn't know the Grand Canyon is in the way.

Like most things, it's not as simple as asking "what do I buy?"

--Do you need maps and if so how accurate and how much do you want to load and unload and update them?
--Do you need color display? (easier to see)
--How big of a screen do you want? Boating you want BIG, Hiking/paddling you want SMALL. Car (SatNav) is medium.
--How easy is it to use? Can you use it with one hand while steering the boat? Can you operate it with gloves on?
--Water proof? How much? 3 meters? (you'd think they would all be but they are not, Garmin told me, a waterproof bag is better and cheaper so they don't waterproof ever model) Water resistant to mist and rain is common.
--Battery life? Most of mine will not make 8 hours so I have to turn them off for long crossings or trail heads to conserve batteries. (I like navigating with paper charts so this doesn't bother me to check every few hours with the GPS and then turn it off)

Lastly, if you don't have a lat/log or waypoint you want to go to, don't expect much. Sure they tell you your at 94 50.45W but were is that? Your maps will not tell you about every hazard to navigation so your still going to need the skills you got in cub scouts.

A gps saved me from spending a long cold night in the woods when I lost a trail on a solo day hike. I was miles from help and lost. I had a waypoint from the day before otherwise I may have been no more.

[grumpie]

Thanks john and Steve, I'm not looking to use it to go from point A to point B but looking to be able to return to point A and B and mark in be between. I know that I will need a depth finder also for mapping purposes.I have a garmin 2720 with a port to plug in a lap top for mapping.
I'm thinking about a class on crime scenes mapping.

[DiverQueen]

In the boat we have an Eagle FishElite 500c which has both depth and GPS.  As far as handheld, I have a very old Garmin eTrex GPS.  Without having military contacts, you will be lucky to get within 50 ft. of plotted waypoint.  The real question is...How many satellites are you in contact with and how close are they.

[aknelsonone]

Those things are usually accurate (for national security reasons) better than 30 yards.
The units for surveying can get to 3 yards.  And at best to one yard with a bit luck and a lots of references.
The accuracy is dependet on the time base resolution in the semiconductors chips used to do the GPS math. The military chip versions are restricted to certain users and not for general public use.

Andreas

 

[scubafreek864]

My Garmin Etrex does just fine for finding my waypoints of the wrecks on Minnetonka.  I am too cheap to upgrade my GPS right now.  ;D

[grumpie]

thanks guys and lady when i get a little farer along we can get together in a ( big ) parking lot and see how we do.

[popolarbear]

I agree Lowrance H20 is nice for the money. and cabalas has some in the bargain cave. i think $100 range.
I felt they chew up batteries, as we were constantly changing batteries. but in retrospect all my hand held units seem to use them quickly.