same GPS cords on lake master, but driffrent depths, Whats up!

[over the limit]

I have been mapping some lake bottom spots,on the big pond, and i have found that,if you bring up the same gps cords under, Reel bottom, DNR, and ProMaps, you will get very driffrent depths, as much as 18 feet, which map is correct or are none of them, Does any body know. TIA

[Paul Waldowski]

For MilleLacs I have found the Reel Bottom map to be dead on with my GPS.

[Captain B.R.K]

Quote:

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I have been mapping some lake bottom spots,on the big pond, and i have found that,if you bring up the same gps cords under, Reel bottom, DNR, and ProMaps, you will get very driffrent depths, as much as 18 feet, which map is correct or are none of them, Does any body know. TIA

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Explain please

I have a Lake Masters Mille Lac's Lake fold out, water proof map ($15.99) and have punched in the coordinates for some of the flats listed on the map into my GPS. I recently had the opportunity to see their Garmin Promap software (downloadable contours of the Lake--3ft contours) in use on a Garmin Map 76 and the coordinates on their maps and as well on the promap fold out were exact!

When the GPS unit said it should be 27ft, depending how acurate the unit was acting (20-30ft difference--- WAAS), I drilled a whole and I was sitting on 27ft of water.

I was out Saturday and every where I wanted to drill on the transition, tops of flats or out on the plains---I was on top of everything with the use of the map and gps unit w/the software!

[jigginjim]

I have found that different times of the year give me a little different location. Plus who really knows what the error is between day to day readings. dead on today maybe 30 feet next week.

[metrojoe]

The DNR maps may look similar as far a structure goes, but the structures location is incorrect. By that I mean when you plot a ProMap series coordinate onto a DNR map it will not be the same location. This shows the inaccuracies in the DNR map. Trust the ProMaps. I've got the ProMap of White Bear Lake and it has never failed to put me on the spot. This could be the reason your seeing different depths.

[over the limit]

This is for the lake master software progam,

if you line up the gps cords on the bottom of the computer,

lets say N 46,9,699 by W 93,44,044 The dnr map says 25 feet deep, and the reelbottom says 14-15 feet deep,

and pro bottom says 16-17 feet

[Rick]

The DNR map is not very accurate at all. The Reelbottom is older and the ProMap Series Lake Maps are the most recently mapped and very accurate.

The maps are valuable for structural locations. Water depth can vary from year to year. Lake depth has been known to drop when it's a dry season or rise when it's a wet season. Even by feet.

[metrojoe]

Your comparing apples and oranges. Of course the coordinates are all the same, the problem is the maps are not all drawn to the same level of accuracy. The methods used to obtain the data to draw the DNR maps were not nearly as accurate as the methods used to draw the Reelbottoms or ProMaps. I wouldn’t worry about a foot or two difference in water depth. It appears the Reelbottoms and ProMap were drawn with about the same amount of accuracy.

Try this, print up a copy of each map (DNR, ProMap, Reelbottom) at the same scale. Over lay the maps and hold them up to a window or some light source. Line up the shore lines and you will see the maps are not drawn the same. I’m sure the ProMap and the Reelbottom line up fairly well, but the DNR map will not match either.