Military map datums

[+Woodstramp]

Have a young man in our family who will probably be deployed overseas soon. He's taken up geocaching, so I gave him an Etrex. Me and he have been teaching each other. I teach him GPS and he's taught me map/compass land navigation. He also thinks he could take the GPS with him when he's deployed. He thinks it'll be useful for marking and recording things in his future work.

 

In additition to showing him how to use the Garmin for caching I told him that the coordinate system can be changed over to match the military maps he'll carry in the field. MRGS system (instead of the Lat/Lon we use for caching). He thinks that will be great. He even had a land-nav map they gave him for a recent training school he went on.

 

We were looking at his map and could not find a datum listing (like USGS quads do) so I could set it in the Etrex. We set the coord system on the Etrex to MRGS, no problem. I know that datum setting is important for accuracy. I wondered if the military issued maps are the same datum world wide? If so, what datum do they use. Thanks.

[+GPSlug]

It's all WGS84.

 

Pretty much the whole impetus behind WGS84 and its predecessors was to have a consistent world-wide datum for all the U.S. military maps.

[+Woodstramp]

GPSslug....thanks...we`ll keep it on WSG84.

[LowranceTracker1]

Most of the US forces in Afghanistan are using the Garmin Foretrex 401 model because of its hands free operation.... However, I do know that members of the British SAS are using the Etrex. Regardless, I would consider using the GPS sparingly to save battery life etc..... Use map and compass, and keep places like his unit command post coordinates in the GPS ready to go in case he gets bewildered. He can use the GPS to give him a bearing to a location he wants to go to, then shut it off and follow his compass, occasionally stopping to confirm he is still on track with the GPS.

[Maggie488]

Have a young man in our family who will probably be deployed overseas soon. He's taken up geocaching, so I gave him an Etrex. Me and he have been teaching each other. I teach him GPS and he's taught me map/compass land navigation. He also thinks he could take the GPS with him when he's deployed. He thinks it'll be useful for marking and recording things in his future work.

 

In additition to showing him how to use the Garmin for caching I told him that the coordinate system can be changed over to match the military maps he'll carry in the field. MRGS system (instead of the Lat/Lon we use for caching). He thinks that will be great. He even had a land-nav map they gave him for a recent training school he went on.

 

We were looking at his map and could not find a datum listing (like USGS quads do) so I could set it in the Etrex. We set the coord system on the Etrex to MRGS, no problem. I know that datum setting is important for accuracy. I wondered if the military issued maps are the same datum world wide? If so, what datum do they use. Thanks.

[Maggie488]

There is one type of gps that is not allowed in country simply because of the insurgents ability to track and intercept its signal. It is not the eTrex or Oregon...that I do know. I use my Oregon to mark my waypoints, just in case something happens. That being said, I MUST delete them when I'm back at base for security reasons. And all waypoints must be deleted prior to leaving for the states again. There are plenty of military maps here that he could use to plot his current and future locations and then check the terrain. This is something that I did immediately upon coming in-country.

I used to have an eTrex gps and I do know that it will give him a 10 digit military grid coordinate. All he has to do to convert that to the commonly used 8 digit grid is simply drop the last number in each line. For a six-digit...drop the last two and for a four-digit simply drop the last three.

Believe it or not there are geocache sites here in Afghanistan. I have not had time to search for them but they are here and inside secure areas. Good luck to him.

[+Woodstramp]

Most of the US forces in Afghanistan are using the Garmin Foretrex 401 model because of its hands free operation.... However, I do know that members of the British SAS are using the Etrex. Regardless, I would consider using the GPS sparingly to save battery life etc..... Use map and compass, and keep places like his unit command post coordinates in the GPS ready to go in case he gets bewildered. He can use the GPS to give him a bearing to a location he wants to go to, then shut it off and follow his compass, occasionally stopping to confirm he is still on track with the GPS.

 

That is the way he said he intends to use the GPS....as an aid to what he calls his "analog" stuff. Never fiddled with the Foretrex model..will study on it. Thanks for that recommendation. Can you load detail maps to one of those models?

 

As it stands now I gave him an Etrex, just to get familiar with a handheld. My intent is to give him my 60csx before goes. IMO, of the GPS units I've used, it is the one I'd choose to take for real hardcore field use. That thing has outstanding reception and gets at least 20 hours out of a couple of AA's. I also have a tough little Delorme PN, but it's shorter battery life will leave it here in the States.

[+Woodstramp]

There is one type of gps that is not allowed in country simply because of the insurgents ability to track and intercept its signal. It is not the eTrex or Oregon...that I do know. I use my Oregon to mark my waypoints, just in case something happens. That being said, I MUST delete them when I'm back at base for security reasons. And all waypoints must be deleted prior to leaving for the states again. There are plenty of military maps here that he could use to plot his current and future locations and then check the terrain. This is something that I did immediately upon coming in-country.

I used to have an eTrex gps and I do know that it will give him a 10 digit military grid coordinate. All he has to do to convert that to the commonly used 8 digit grid is simply drop the last number in each line. For a six-digit...drop the last two and for a four-digit simply drop the last three.

Believe it or not there are geocache sites here in Afghanistan. I have not had time to search for them but they are here and inside secure areas. Good luck to him.

 

maggie,

 

Thanks for the info. Particularly the security stuff. I'll pass that on to him. Also, thank you for your service. Good luck...back at you!