For Those Without Detailed Topo Maps

[nathanhooper]

Here is a link that you can at least look over before going out. May be able to print them out.

http://webapp.navionics.com/?lang=en

[showmebass]

Awesome link.

[Mike jones]

I have this link saved on my favorites!

[jdmidwest]

That is a nice site. I found it earlier this spring while researching Reelfoot lake. Nice contour lines.

[fishinwrench]

That is a nice site. I found it earlier this spring while researching Reelfoot lake. Nice contour lines.

Yeah those lines are cool looking. It's too bad that so much of it is totally bogus.

Seems as though someone spent a lot of time bending lines via a computerized image overlay....filling in the gaps between areas of known contour locations, which ironically falls far from where all of my fishing seems to happen.

On the areas of lakes where they truly lack accurate or complete data they really should just avoid faking it.

An improvement IMO would be to highlight those unknown zones with a notation of something like...."This image may or may not be anywhere close to accurate, our designers were just playing on Paint and guessing. Hell they've never even been in this state before, much less halfway back in horsepecker branch !".

[bfishn]

Yeah those lines are cool looking. It's too bad that so much of it is totally bogus.

Seems as though someone spent a lot of time bending lines via a computerized image overlay....filling in the gaps between areas of known contour locations...

True that. From the USGS;

" The most recently published figure of overall absolute vertical accuracy of the NED (national elevation database) within the conterminous US, expressed as the root mean square error (RMSE) of 25,310 reference points is 1.55 meters."

And that is for the current dataset. Since topo data for lakes like Table Rock, LOZ, etc, was derived from pre-impoundment photogrammetric images from the ~'50s, the base resolution would have been far less than the current 1.5M. There's a good reason our old local topos were limited to 10 and 20 foot intervals.

Nowadays, when differential GPS with a nearby land based elevation reference can reach accuracies of inches or less, those one foot intervals are an easy sell. Too bad they're mere extrapolation.

[jdmidwest]

But they do give you a general idea of where to go. The chartplotter and sounder does the rest in real time.

For a free service, it is nice. I have downloaded old topos of lakes before they are formed to find roadbed and to find feilds and timber areas. Another good resource.

[nathanhooper]

Yes, I don't look at it as a exact detail, but rather something to see where humps, underwater points, river bed, creek bed, road bed, and bluffs are. And you can get a good estimation from this map for sure. Use your sonar for the rest. I have used generic topos up till now and they give you a general (100ydx100yd) area of where things are, but this narrows it down to 25yds at least.

I would like to know where you can get topos that show old fields and such. I have heard of them before.

[bfishn]

Historical topos are at;

http://nationalmap.gov/historical/

You just need to know the quadrangle names you're looking for.

[Bird Watcher]

Yeah those lines are cool looking. It's too bad that so much of it is totally bogus.

Seems as though someone spent a lot of time bending lines via a computerized image overlay....filling in the gaps between areas of known contour locations, which ironically falls far from where all of my fishing seems to happen.

On the areas of lakes where they truly lack accurate or complete data they really should just avoid faking it.

An improvement IMO would be to highlight those unknown zones with a notation of something like...."This image may or may not be anywhere close to accurate, our designers were just playing on Paint and guessing. Hell they've never even been in this state before, much less halfway back in horsepecker branch !".

I've found it surprisingly accurate where I've used it. YMMV, I guess.