Garmin G3 Navionics maps are inaccurate

[bwjay]

I got an echoMAP Plus 93sv last fall with the 2019 maps, and have updated it to the 2020.0 maps, and have found many lakes to be inaccurately mapped. Some lakes it shows me paddling on land. Some lakes it shows humps where there are none (or the hump is 50 feet to the side). Sometimes it shows dropoffs where I'm supposed to be in 30 feet of water and I'm in 10. Some lakes seem spot on, and others seem wildly inaccurate. I'm 95% sure the issue is not with the GPS in the unit, as it shows me close to some land-based features like docks, ramps, and river/creek channels that enter/exit the lake, but the actual lake topography is inaccurate in many spots.

 

Has anyone else observed this to be true? Minnesota has a lot of lakes so I'm not expecting every single one to be perfect, but I've been pretty disappointed by map accuracy and basically consider them guidelines. I can't trust them for putting me "on the spot" which is really sad. The Navionics acquisition was supposed to give them even better maps but they seem really hit or miss. I love almost everything about my 93sv except the map accuracy. It's making me consider trying a Humminbird just to see if the maps I can get are actually accurate, which I don't want to do because I think their units are incredibly overpriced and I enjoy my 93sv. I just want to be able to go to a point, hump, or ledge that's on the map, and actually be on it when I get there.

 

Any thoughts from anyone else? I'm having a remarkably hard time finding anyone else talking about this.

[Tennessee Boy]

I've found errors in every map I have ever used.  The Navionics maps around here are pretty bad.  The Lakemaster maps for most of the lakes I fish are based on recent sonar surveys and offer details you want find on any other map.  They also have errors you want find on others maps.  I think you have to judge each map on it's own merits.  Navionics may have the best map of a particular lake.  Lakemaster may have the best for another.  In some cases,  they may all use the same publicly available data for a given lake.

[bwjay]

  On 6/26/2020 at 12:22 AM, Tennessee Boy said:

I've found errors in every map I have ever used.  The Navionics maps around here are pretty bad.  The Lakemaster maps for most of the lakes I fish are based on recent sonar surveys and offer details you want find on any other map.  They also have errors you want find on others maps.  I think you have to judge each map on it's own merits.  Navionics may have the best map of a particular lake.  Lakemaster may have the best for another.  In some cases,  they may all use the same publicly available data for a given lake.

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Well, that is both disappointing and comforting to hear. Disappointing because I would LOVE to be able to rely on my maps to get to structure I want to fish, but comforting knowing that I can probably skip the $1500 Humminbird unit I was considering because the maps aren't going to more accurate across the board. I know I can do my own mapping if I tool across every single lake which just isn't an option. What blows my mind is how inaccurate some of the maps are.... like, where did that data even come from? Some of the topographical features shown don't even exist in the lake, and I find it hard to believe that the lake bottom has changed that significantly in, let's say 50 years, if they were mapped that long ago. I'd love to understand more about the mapping process, but it wouldn't change the fact that sometimes I pull up on some flats that break out to deeper water and the break line is 50-100 yards further into the flats than it looks on the map, or that the flats that are supposed to be 8-10ft are more like 4-6ft.