So I'm looking at buying a fishfinder with GPS to fish a local 600 acre reservoir. There are no lake maps available, and I don't even know if GPS would help me. If the lake is not in the memory of the GPS, does it show up? The lake is about 5 years old, so I don't even know if it would show up on the GPS as a lake? Of course, i guess the only way to find out would be to buy one and then take it out on the lake, but if not, i'm out some serious money.

if you ever find deep structure it is a must have. mark the stuff you find, brush piles spawning areas etc. remember spot on the spot so yeah by lining up your boat with a farm house and the third telephone pole may get you close but gps will get you on it.

the other way to go is get a hand held. I use a lowrance H2O which I have a lakemaster chip in. the screen is small and annoying but if money is a concern it is a cheaper alternitive. My depthfinder was $170 and my gps was $170 so $340 for both. I do wish it was all in one but come hunting season I am glad for the hand held.

If there are no maps of any kind available for your lake, it probably is not on any map software that is preloaded or memory card based for any Sonar/GPS unit of any brand.

One of the best sources of lake map software is Navionics. Check their website for the region you are in and there will be a list of waters that are included for each region.

Mapping is not a necessary function of GPS units. Mapping is just overlayed on a GPS plotter screen so the position of waypoints, routes, and tracks have a visible reference. The GPS functions the same with or without any mapping software.

If you state what water you are referring to, maybe someone that has GPS mapping for that area can let you know if they have that water on their unit's map software.

One of the lakes I fish a lot has no mapping of any kind available, but I have over 50 GPS waypoints for that water. I have those by being on the water and saving those postions. My Chart view shows I am on land when I am there.

You can make your own topo map of that lake by using acmemapper. Just find the lake and print the Land Topo and Satellite views. I print the Satellite view on plain paper, print the Topo view on clear translucent paper, put one on top of the other and have a lake topo map. Just don't change the scale between views.

Here is one I did of part of a lake:

One option is to visit a BPS, Cabelas or Gander Mountain and look at the display units and see if the lake is programed into the unit. BPS will also install the different chips available to check detail. Not sure what part of Georgia you are in but if you are close enough to drive this will eliminate any doubt...........Al

Wayne, thanks for the great info, I'm definitely going to try that. One of the best parts of having gps/lake maps is the contours/topo of the lake. I'm really trying to get into offshore structure fishing and without contours, you're really not at full potential.

Wayne is right on. You can also punch in a waypoint and return to the spot easily.