Lowrance experts,need advise

ive never used navionics is it really that good?

Navionics or other mapping chips are awesome and are definitely worth purchasing.

Navionics doesn't cover some of my favorite lakes, so for many years I didn't buy a Navionics chip.  From years of fishing and trolling around on those lakes, I have developed a pretty good mental picture of the underwater topography of the lakes, I have learned to locate some underwater features by triangulating off landmarks on the shore, and I have set waypoints to help me find various underwater features. 

Then I finally purchased a Navionics chip, and I wish I had bought one years ago.  For those lakes which are covered by Navionics maps, the bathymetric maps provide a much more detailed picture of the underwater contours of the lakes than my mental map, and it's terrific to be able to go right to or along various features.  You can see what the Navionics maps look like by going to the Navionics Web App at http://www.bluewaterweb.com/Navionics-Map.html, but looking at a printed off Navionics map isn't nearly as good as having the maps on your fish finder. If you load a Navionics chip onto your fish finder, you can see exactly where you are with respect to the topography of the lake bottom, you can go right to mounds, right along underwater canyons or dropoffs, right through saddles, or follow contour lines around the lake, and you can turn before you plow your downrigger weight into an underwater ridge.  If you don't have Navionics maps or some other mapping chip, buy one.  You won't be sorry.

Because Navionics doesn't cover some of my favorite lakes, the next time I buy a fish finder, I'm going to get one which will build a bathymetric map of a lake which isn't covered by Navionics by assembling the sonar returns which the fish finder records as you pedal or paddle around the lake.  If you have used a fish finder with this capability, I'd interested in a report on how well (or not-so-well) the system works.