Reply With Quote1. Don't put a lot of faith in GE unless the particular area of concern has been previously verified based on the GE update at the time relative to positions of "known" accuracy.
From what I understand your GPS should be good to about 10 meters or better.
Most GPSs somewhere in their menu should be able to display "current calculated error".
As has been mentioned before, there are biggere variances in the sort of mapping we use than the GPS.
As stated soo many places and times, there is no substitute for a visual look out.
This is why beacons are beacons.
Now consider what "Google Earth" is it is a free to use aerial photograpy product.
It will be automaticlay stitched together from a large number of frames, many of them not taken from directly above....the image of my house is clealy taken from the south.
If google earth covers the entire globe, what datum does it use and what grid system does it use to resolve the irregularities of the earths shape......
I think you are expecting far too much from google earth.
If you want to get mapping that is accurate in the ground (or water), you fist must have a datum, then you have to have a corrected portion of a grid, that grid then has to be referenced to some on the ground real references, then the maps have to be drawn accuratey in relation to all of that.
From my limited experience, even the official published maps for navigation have limited accuracy.
It is important to understand the concept of mapping.......it is a picture designed to show you approximately what should be there so you can confirm it by ither means and thus establish you location.
cheers
Its the details, those little details, that make the difference.
1. Don't put a lot of faith in GE unless the particular area of concern has been previously verified based on the GE update at the time relative to positions of "known" accuracy.
I was at the local boat ramp and noticed a sign for a restricted area at the river mouth, the coordinance were located on existing channel markers. Now i can find out how accurate my unit is.
thanks to all for your replies!
jerson
I would not rely on the chanel markers being where the declared co-ordinates are.
Unless those co-ordinates are declared as being accurate for the channel markers.
cheers
Its the details, those little details, that make the difference.
The channel markers in question are the lead markers into the main shipping channel of the river.
They should be close enough for what I require.
I've always been an optimist.
I remembered i have a garmin etrex, replaced the batteries, compared the readouts from the matrix & handheld, nearly exact within .01, google not reliable.
jerson
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