Coordinate Systems Question

[+hybridgeek]

Hey folks,

I recently got accepted to The National Map Corps, and I noticed they say I should have my GPS set to NAD83. This made me think, "is my gps set to NAD83?" I found out mine is set to WGS84, which should theoretically be newer (by theory they actually number them by the year as with NAD23 and 83). Which one is better to use?

 

I often find myself using hints for caches, and realize, "what if everyone else is marking coordinates using NAD83, and so maybe this is why I'm always off slightly..." Could this be? I wouldn't expect it to be that far off, but should I be using NAD83 for Geocaching, or WGS84 better? What is the difference?

 

I'm taking a cartography class at my community college and we learned NAD83 was the latest, WGS84 wasn't even mentioned.

 

Thanks in advance for the help as always!

Hybridgeek

[+Cardinal Red]

This is not a new question. The Geocaching standard is WGS84. The National Map Corps standard is NAD83. Good quality maps will generally be in NAD83. Thus the reason a cartography class would consider NAD83 "the latest".

 

There was a time when WGS84 and NAD83 were very nearly identical (within a centimeter or two). Since then, they have both been redefined and can now vary by as much as a meter or two. To your consumer grade GPS, a meter or two is still nearly identical. Your consumer grade GPS can not tell the difference. I have reason to believe that Garmin GPS units (only brand I have ever owned) actually treat them as EXACTLY the same.

 

So use what ever setting makes you feel good. You have to spend several thousand dollars minimum on a Surveyor grade GPS unit before it makes any difference.

[+hybridgeek]

Thanks! Good to know. I hope the map corps doesn't have a problem with me using an Explorist 600.

 

Hybridgeek

[+Cardinal Red]

They realize they are going to get these coords from consumer grade hand held GPS units. Your Explorist will be fine.

[+Lil Devil]

Most (all?) consumer GPS units are set to WGS84 out of the box which is why the geocaching standard is WGS84. One less thing for a newbie to worry about.