GPS Coordinates question

bikefreakvinnie

Hi folks,
I have just been given an old secondhand garmin etrex H (the one with the lcd screen). Could anyone tell me what units I should set it to?
(the units are located at: Menu-Settings-Units-Position format?)
Should it be set to "Irish Grid"?

And my other big question is - can I take coordinates off google maps or the ISO website and enter them into the Garmin as way points (I have tried to do this and realised that there are so many different grid settings that I need to use the same one...)

Ideally I'd like to be able to take coordinates from google maps and enter them as waypoints...
(I've searched the forum and don't see that this question has been asked before)

Thanks in advance for any help with this

hmmm

Nice one, they're a good little GPS.

Yes, Irish grid. And the "map datum" is "Ireland 1965"

The manuals for the device are on the Garmin website
https://buy.garmin.com/shop/store/manual.jsp?product=010-00631-00&cID=144&pID=8705

You can enter waypoints, the manual will tell you how. I seem to remember you had to hold one of the buttons down for a second or two and it will ask you to enter the details.

I'm not sure what to do about Google maps because that doesn't use the Irish grid, hopefully someone else can help.

bikefreakvinnie

Thanks for that hmmm!

After a further bit of searching from a previous boards post I found this converter:

http://www.fieldenmaps.info/cconv/cconv_ie.html

It converts google map coordinates into Irish grid-Ireland 1965 coordinates, and i've tested it -it seems a success so far.
After setting the units as you told me hmmm I entered google maps coordinates into the first box "WGS84/ETRS89", and got the results from the blue irish grid box...

hmmm

That's a great site, thanks

jolly47roger

If the Etrex has a PC connection, look at GPSU as a program for entering coordinates and downloading routes. Much easier on a proper keyboard!

NotCarrotRidge

First, you need to understand a bit about Irish co-ordinates. There are two systems in use. The oldest one uses the TM65 projection and is called Irish National Grid.

This is the grid being used on the discovery series maps (and was on the older 1/2" maps). If you use this on your GPS, it will not show the first number. For example, if you're at 212000E and 313000N, what you will see is 12000E and 13000N. I would hope that you know where you are to the nearest 100km, so as long as you just bear that in mind, you'll be grand! Eastings go from about 030000 to 370000 in this system.

The more recent one uses the WGS84 projection and is called Irish Transverse Mercator (ITM). Eastings in this go from about 425000 to 690000. This effectively means that there is no overlap, so you'll know which system you have co-ordinates in.

When you say that you're using Google Maps/Google Earth, does that mean that you're just taking co-ordinates from Google Earth and using those to create waypoints, or are you creating kmz files and trying to transfer them to the GPS? If the former, you could use the OSI mapper (www.osi.ie click on New Interactive Map) and get your co-ordinates in ITM from there. One caveat is that think they're deliberately inaccurate to about 50m.

If you're happy to just follow waypoints, why not just set your gps to standard lat long and use the google co-ordinates? You can always go back to Irish co-ordinates if you need to check where you are on a map. I know that's a pain, but if you prioritise which system you're using (GPS or map) they it should work out.

NotCarrotRidge

bikefreakvinnie wrote: »

Thanks for that hmmm!

After a further bit of searching from a previous boards post I found this converter:

http://www.fieldenmaps.info/cconv/cconv_ie.html

It converts google map coordinates into Irish grid-Ireland 1965 coordinates, and i've tested it -it seems a success so far.
After setting the units as you told me hmmm I entered google maps coordinates into the first box "WGS84/ETRS89", and got the results from the blue irish grid box...

If you've set your GPS to the 1965 Irish National Grid setting, then the blue box is your man.

Alun

NotCarrotRidge wrote: »

First, you need to understand a bit about Irish co-ordinates. There are two systems in use. The oldest one uses the TM65 projection and is called Irish National Grid.

This is the grid being used on the discovery series maps (and was on the older 1/2" maps). If you use this on your GPS, it will not show the first number. For example, if you're at 212000E and 313000N, what you will see is 12000E and 13000N. I would hope that you know where you are to the nearest 100km, so as long as you just bear that in mind, you'll be grand!

Luckily someone has thought of this, and the whole country is split up into 25 100kmx100km squares each identified by a single letter (A-Z not including I). On every Discovery series map there's a small diagram included in the map legend showing which square, or squares apply to that sheet. The letters are also shown on the map itself where any grid squares intersect, such as on the SW corner of sheet 56.

This letter is displayed alongside the coordinates shown on Garmin GPS's (although rather confusingly prefaced by an I), as follows ...



The British OS do the same thing except they use two letters per grid square.