#### grumpyolman

##### New member

I work with and help train search and rescue units. We just got brand new hand held GPS, Garmin E-Trex HCx (H=Highsensitivity C=color x= capability of inserting more memory) and I am working on teaching the folks how to operate that unit.

I can't understand why people are seemingly stuck on Lat and Long. It's a terrible navigation coordinate system for use on land. For ships and aircraft it's probably the best. For land it rots. Check out UTM...Universal Transverse Mercator. It's base 10, not base 60 like lat and long, and every section of the Earth is divided into 1000 meter squares. Each section has a unique identifier that's easy to read. All the Topo maps have UTM already drawn or at least are on the borders. Our new HCxs consistently give an accuracy of navigation within 7 feet. Real quickly now, tell me how many seconds are in 300 meters? Everyone already knows how far 300 meters is and nobody navigates in terms of distance with Lat and long.

The Coast Guard uses Lat and Long in their helos, although they have the equipment and knowledge to use any coordinate system. Did you know there are three kinds of Lat and Long. In the movies and on TV they use degree, minutes, and seconds, Most aircraft use degrees with decimal minutes. Somewhere somebody uses decimal degrees. Anything you ever learned about math isn't going to help a bit in calculation when you are mixing base 60 with base ten.

National Search and Rescue, FEMA (Don't know if that's a good endorsement), the major oil companies, and on and on use UTM.

I can teach anyone to know exactly where they are on a map with UTM and a GPS set up to UTM in about 2 minutes. UTM is not new. There's tons of info about that coordinate system on the net.

Know about Datum? That's the methods used to measure the distance between objects on the surface for the map YOU ARE USING. Most modern navigational maps use WGS84. All the topos used NAD27. If your GPS's datum isn't set to match the map you are using, you can have an error of over 200 meters of where your locations really is. Even though everything else is correct. That's not a problem for a helo flying at a thousand feet as they can easily visually try to locate that spot. However, if you are hiking into a ghost town to find where the saloon was on that 1890 map you found at the library and you are 200 meters off because you didn't set your datum to match the map being used, you are going to be really frustrated. Jim