400t Off Course with Google Earth

[SL3]

Does anyone know why I get a 100 yard variance from my 400t to my Google Earth? First let me say that when I’m in the field and I mark an area on the 400t and come home and place the coordinates directly into Google Earth it’s pretty dead on.

 

The problem only arises when I’m not in the field and find a new location on Google Earth, and then mark it. I then transfer the coordinates into my GPS to locate at a later date. The Google Earth coordinates is always about 100 yards off from the GPS and vice versa.

 

Why does the transfer of coordinates work from field to home, but not from home to field?

[+dfx]

datum problems? coordinate format problems?

 

it would help to know exactly which steps you're performing to get the coords out of google earth and how you enter them to the GPS. also a specific example would be useful (i.e. a certain location, which coordinates you're getting, where they appear to be for you and where you'd expect them to be).

[SL3]

Ok my example would be S. Grade Road x State Park Road off Hwy 76 in San Diego County Ca. If you locate it on the Colorado 400t and mark it you get N 33 18 47 2 - W 116 51 57 4

 

But if you mark it on Google Earth you will get N 33 18 49 64 – W 116 51 54 91. The 400t mark is always just about 100 yards off.

 

I did change my position settings to match with Google Earth from hddd mm.mmm’ to hddd mm’ss.s” and I usually get pin point accuracy when I mark a waypoint in the field.

 

I’m thinking it might be a mapping problem with the 400t. The marked roads on the 400t may not be as true as the ones in Google Earth.

[+dfx]

Ok my example would be S. Grade Road x State Park Road off Hwy 76 in San Diego County Ca.

if i interpret google maps correctly, those two roads don't intersect at all. it seems to me that state park road ends in canfield road, which then continues to become east grade road, while south grade road intersects with east grade road. maybe that's where the problem comes from?

[SL3]

You are correct. It should be Co Hwy S6 x State Park Road. But on the 400t it marks that same location as S Grade Rd x State Park Rd (I just marked a general location that was easily seen on both maps). Either way the marks will always be 100 yards apart no matter where I mark in that area. Go ahead and try to mark a section of the road in that area on your GPS, and then do a search with that coordinate in Google Earth. See if your not 100 yards off. If not then it must be one of my settings.

[+dfx]

Go ahead and try to mark a section of the road in that area on your GPS, and then do a search with that coordinate in Google Earth. See if your not 100 yards off. If not then it must be one of my settings.

unfortunately i don't have the same maps as you on my GPSr (which ones are that?), so i can't do that myself