Secondary Datum

[+Skip_]

I have a Sport Trak Map, and it has settings for a primary and secondary datum. Primary is set to WGS84, does the secondary setting matter at all?

[+Corp Of Discovery]

I set my secondary to UTM. Don't think it matters, and sometimes you may just need it. You can see the secondary coord on the 'position' screen.

 

Edit: Oops. You are talking about datum and I replied with coord system. If you are using it for geocaching you probably will never need another datum, especially if you live in the US.

Edited May 3, 2005 by Corp Of Discovery

[+Cardinal Red]

This is an option that you can use if the need arises, or ignore if you don't need it. Many GPS units (Garmins for example) can only be set to 1 Coordinate System and 1 Datum at a time. If I (a Garmin user) want to make full use of an NAD27 Map while searching for a WGS84 Cache, I have to take that into consideration and adapt.

 

You could set up the Primary with the Cache data of Lat/Long and WGS84. You could set up the Secondary to match a UTM NAD27 Map, and keep track of both simultaneously. But if you don't need that, just forget about it.

 

Answers To Similar Question (with some confusion thrown in that you can ignore)

 

Pay particular attention to posts by Curious George and EScout.

[+Xangxa]

Benchmarks use NAD27 if I remember correctly. If you hunt those, it might be handy to set your secondary to that.

 

EDIT: The NGS converted their data sheets to NAD83, which is approximately WGS84, so it depends on how pedantic you're feeling.

Edited May 3, 2005 by Xangxa

[4x4van]

On the position screen on Magellan, hitting the rocker switch right or left will allow you to see both sets of coordinates simultaneously. I have my primary set to DD*MM.MMM in WGS84, while I have my secondary set for UTM in NAD27 to match typical topo maps.