GPS Datum Question

[iffwalleyes]

Does anyone know the answer to my question? I have a lake map the has lat/long coordinates on it it was done on the NAD 83 datum but all my other waypoints are saved as WGS 84 datum. So the question is can I switch the datum of my GPS to 83 enter in the points off of the map and then switch it back to WGS 84 and will it automatically convert it? When I entered the cordinates in at first I entered the 83 numbers but I was in the WGS 84 mode so it shows my points on the opposite side of the lake.

[SteveWilson]

I don't know if your GPS will do datum shifting. For a few points you can try this http://jeeep.com/details/coord/ it seems to work fairly well. You could also try downloading this http://gpsinformation.net/holux/tatuk-calc.htm

[HateHumminbird]

Iffwalleyes:

Check out a previous post:

http://www.fishingminnesota.com/forum/showflat.php?Cat=&Board=UBB37&Number=649131&Forum

The guy's GPS unit did the shifting for him as soon as he switched his datum to the appropriate scheme.

Let me know if you have any other questions, I might be able to help.

Joel

[Big-Al]

Almost all GPS's would shift the datum for you, BUT between NAD 83 and WGS 84 there is virtually no difference. The same coordinates in the the two datums put the waypoints right on top of each other. You would not be across the lake. That certainly is not true with all datums. If you happened to be in NAD 27 versus NAD 83 (or WGS84) there is something like an 80 meter easting and a 15 meter northing difference.

[dockehr]

iffwalleye, the reply with regards the NAD83 and WGS84 Datums is correct. Your problem may be related to what format your datum is in. Are you converting, for instance, degrees, minutes, and seconds into degree, minutes, and seconds and not degrees, minutes, and thousandths of degrees? Make sure, as I have run into this on occasion, when typing in someone's co-ordinates. I didn't realize that they were in a different format. That will throw your results off. Good luck and good fishing.

dockehr

Dr. Roland E. Kehr, Jr.

Lindy Tackle Company

[iffwalleyes]

I think it is probably more of a issue with the map that I was using. I talked to the person that made the map and they said if I was having problems to let them know so I think I will be doing that.