Which Waypoint Conversions

[+A.T.Hobo]

I've been using Degrees and minutes (MinDec) on my GPS. However, I also notice that there are other conversions and saw that a different one was used on the waypoints for "Caches along a route" when you print a list:

I see there is an option for:

Normal GPS Coordinates (WGS84 Datum)

Decimal 36.32902 -79.68863

DDD MM.MMM N 36° 19.741 W 079° 41.318

DDD MM SS.SSS N 36° 19' 44.4612" W 79° 41' 19.0788"

 

Older Datum (NAD27)

DECIMAL 36.32894 -79.68886

DDD MM.MMM N 36° 19.736 W 079° 41.332

DDD MM SS.SSS N 36° 19' 44.1696" W 79° 41' 19.9104"

 

UTM (WGS84 Datum)

17S E 617701 N 4021240

British Grid

2882316 -6842155 \

 

Here in North Carolina us small town boys get a little confused as to which is the correct coordinates to use on our GPS's.

Which is th best coordinates or conversions to use??

 

Any help??

[+Dread_Pirate_Bruce]

If I understand correctly, it is all the same. The latitude and longitude can be expressed in various ways, all of which are equivalent. It is like having change for a dollar. You could have ten dimes or four quarters. It is all the same. All that matters is the format that your GPS uses when you input coordinates. I'd guess that you can select the format.

[+webscouter.]

Normal GPS Coordinates (WGS84 Datum)

DDD MM.MMM N 36° 19.741 W 079° 41.318

 

This is what the site uses.

[+Corey]

The coordinates on cache pages are always shown in Degrees, Decimal Minutes (DDº MM.MMM). That's what I would use. All those coordinates represent (more or less) the same place on Earth.

 

(Wow, all 3 of us answered at practically the same time.)

Edited October 24, 2008 by Corey

[+tozainamboku]

If you are using a paper map you should use the datum and format that matches your paper map. That way you can find where you are on the map using the coordinates displayed in your GPS. If you are not using a paper map, it doesn't matter which you use. The GPS calculates your position in a 3 axis earth centric Cartesian coordinate system and automatically converts it to the format and datum you select in setup. If you change the format and/or datum on your GPS, it will automatically convert your position to the new format and datum. Most handheld GPS units come setup to use Degrees/Minutes and WGS84 datum out of the box. So that is what Geocaching uses. The conversion page is for people who want to plot the cache location on a paper map.

[7rxc]

I've been using Degrees and minutes (MinDec) on my GPS. ...

 

Here in North Carolina us small town boys get a little confused as to which is the correct coordinates to use on our GPS's.

Which is th best coordinates or conversions to use??

 

Any help??

 

What the others have said is correct... all the same more or less...

The coodinate choice is up to you... GC.com uses the DD MM.mmm form.

The Datum of choice (again GC.com) is WGS 84 a world standard datum.

 

NAD 27 is an OLD datum that is what was used to make a topo map in North America prior to the advent of

NAD 83. If you use an NAD 27 map you should change your GPS to that Datum to automatically correct WGS 84 or NAD 83 so that you can find the correct location on the map... There is a difference of several hundred metres between the two north and east. In my location it's about 10 m for E and 212 m for North on the UTM coordinates... The UTM and Lat/Long grids haven't changed, they simply recalculated how the lines representing the ground features were positioned on it. Basically they found that the 1927 idea of how the world was shaped was a little inaccurate... the new model matches how they calculate the GPS satellite

orbits. Everything works the same way, some things just moved on the map.

 

Doug VE7RXC Elkford BC

[Skippermark]

Normal GPS Coordinates (WGS84 Datum)

DDD MM.MMM N 36° 19.741 W 079° 41.318

 

This is what the site uses.

This is what we use too since it's what the site uses. But, if you choose to use decimal format for instance and WGS84, 36.32902 -79.68863, your GPS will still guide you right to the cache. It's just a different way of viewing the numbers.

 

We've seen some puzzles that require finders to switch their GPS into one of the other modes to solve the coordinates.

[+StarBrand]

Just to clarify - a Datum like WGS-84 is a model of the world that defines a grid system. Depending on where you are at - it differs from NAD-27 by as little as a few feet or as much as 2000 feet for exactly the same coordinates.

 

Format is just a different way of writing exactly the same coordinate - no matter what the datum.

[Skippermark]

Thanks for the clarification, StarBrand. I didn't know how to explain that in an easy to read way.

[+A.T.Hobo]

Thanks to everyone for helping me understand this. This little info will go a long ways in my book of life!!