Hand held gps? - Page 2

Alan Mckewan · 07 October 2001, 22:35

I,ve just got a Garmin Etrex (around 100 quid) and it seems to be a good job, it floats & can be dunked no problems. But putting in waypoints is a bit slow and I dont fancy shelling out on the GArmin PC software. Does anybody know an basic PC software that could just upload waypoints?

geoff · 07 October 2001, 23:43

Have a go with this.
http://www.easygps.com
Its got a programme you can download that should suit your needs.

batfalcon · 09 October 2001, 17:50

I' ve just downloaded the easygps.exe from the site you mentioned above. For the moment I haven't got the connection cable for my Garmin GPS III, (I have it installed on the rib), so I can't test try it. Is it possible to "update" (make corrections) to the map as well , or you can only transfer routes and waypoints?

Keith Hart · 20 October 2001, 08:33

(after a quiet period from me)

Global Positioning by satelite, accurate to a couple of meters - great. Simple, cheap, perfect for a duffer like me. BUT, notice on chart tells me...Satelite-Derived Positions are normally referred to WGS Datum. such positions should be moved 0.02 minutes Northward and 0.09 minutes Eastwards to agree with this chart.

Why are they trying to confuse me? And just who are THEY anyway?

Does this mean that if I am stuck out at sea and am calling for help that I have to read my gps (which SANTA has promised me for Christmas) and then SUBTRACT the above to give my correct position?

Help!

Keith (this may be harder than I thought) Hart

Alan Mckewan · 20 October 2001, 08:52

Hi Keith, forget all the rubbish about accuracies to a couple of metres! Just stop and think what you actually want the GPS for. The way I see it is that you want to able to find your way to (and back from) places. Previously it was just a matter of getting the chart out, drawing a line or two and using your compass to go along that line (maybe with a few clever bits like allowing for tides and checking your position every half hour or so). Once you got within seeing distance of where you were going you steered by eye. With the GPS you do the same thing electronically with the added benefit of not being dependent on visibility for your regular checks on position. BUT you will still drive into a place once you see it!
Most charts are based on info collected by the Navy, hydrographers etc. up to a hundred years ago and it is quite likely that parts of the chart will be much less accurate than modern GPSs claim to be. They have just been corrected and made prettier over the years. Accuracy to better than 50 metres was never intended or expected in those days. If you reckon on a BELIEVABLE accuracy of 50 to 100 metres then you wont go far wrong ( ubless you are spending loads more monet and effort on DGPS but thats another story).
You are right about the different chart datums, but it wont make a difference unless you are thinking of better accuracies than 100 metres. Anyway most very new charts are now coming out with the GPS standard datum. If you are really fussy you can switch your GPS on to the same standard as virtually any chart you may have, no matter how old!!

Keith Hart · 20 October 2001, 09:10

Hi Alan

Thanks for the reassurance. Yes, you're quite right. I want the gps to get me back if there is poor visibility or to help report my position if in trouble. I suppose that in the latter case the lifeboat can zoom in on my marine radio signal for the last bit anyway.

I did not know that you could adjust the gps to the chart settings. This forum should carry an Open University Degree qualification.

Cheers

Keith (now reassured on gps) Hart