There are several differnect types of cards which can be purchased to make better use of the Lowrance GPS/Sonor units.  I am planning on bying the Navionics Fishing hot spots.  I live in the midwest and will only be using it for fishing main lakes.  Is this what most of you guys are running in your GPS units?  Should I consider something different? Thanks!

Check out  http://www.navionics.com/HotMapsPremium_06.asp?RegionID=2  to see whether your lakes are listed in RED.  If they are then at least part of it is in HD, having 1 foot contour interval detail, which can really be an asset finding structure. They use Boston Whalers to survey, so low pool at the time they worked a lake would limit their access. Some of their maps have no data for shallow areas. To me, any detail like that is well worth the expense.

Otherwise you are possibly better off financially as well as coverage-wise with the cheaper Lowrance Fishing HotSpots Elite if your lake(s) are listed at [urlhttp://www.lowrance.com/Mapping/FHSelite/default.asp.

Those maps are usually based on older and sometimes outdated USGS topo maps using data from before a lake was built, so siltation isn't accounted for. Non-HD Navionics maps are also based that way. Some of both also use other bathymetric and navigation map data such as from the USCOE and maritme charts. If you will be fishing coastal waters there are other map sources, as well as for the Great Lakes. Lowrance GPS will use either brand. Navionics has better information for inland navigation channels.

Jim

Definately get the Premium Navionics Hot Spots for your area. If you don't spend the extra 40 bucks now you'll wish you did later.  

I priced both. Check out ebay - the Hot Spots chip wound up costing me about $75 versus about $150 as I recall for the Navionics. Also a salesman at Cabellas told me the Navionics survey left out large portions of some lakes due to droughts and the lake levels being low.

The Hot Spots is working fine for me, have had it out on Grapevine, Ray Roberts, and Fork. RR and Fork have extra fishing detail, was able to locate and follow a creek channel at RR which had lots of suspended fish. At Fork I was able to verify that I was in the lanes although I'd not advise navigating by GPS alone.