Once you’ve selected a map area for downloading, the information is transferred into a “flash memory” (typically, 2 to 8 MB of memory on a blank cartridge or MMC card that fits in your GPS unit). Depending on the level of detail you’ve chosen, a single file can include a state the size of Georgia.

Mapping giant DeLorme recently entered the GPS mapping scene, and their GPS PN-20 hand-held receiver can display both DeLorme maps and aerial imagery. Their Topo USA map software is included.

GPS Applications

Marking waypoints is another strength of GPS systems. You can mark important points like home port, boat ramps, brushpiles, and reefs on your GPS maps so that you can avoid hazards or accurately return to fishing spots, even in bad weather or at night.

Thanks to contour maps offered by such companies as Lakemaster, C-Map, Fishing Hot Spots, Lowrance, and Navionics in memory card, CD, and website formats, you can add waypoints to existing contour maps. When you’re working on your computer with mapping systems, such as those produced by Fishing Hot Spots and Waypoint Technologies, you can move your mouse to spots and set them as waypoints. The system numbers your waypoints and you can name them for better identification. Marking underwater points, inside turns, and sunken islands is simple. This information can then be downloaded onto your GPS unit.

Most GPS units let you place markers or icons on the screen to mark fish or interesting structure for future reference. Most anglers don’t bother to punch in names for locations of caught fish, as they expect them to change, but icons can help define a locational pattern. You can enter them on your computer later or log them into a notebook in case of GPS unit failure. GPS also is a safety feature, provided your batteries don’t go dead. Even on familiar waters, anglers can become disoriented in fog, heavy rain, or other severe weather. Waypoints, icons, or saved trails can lead you to your destination or back to the ramp. GPS has turned many shoreline casters on big lakes into open-water anglers, thanks to the technology’s ability to get them back home over featureless, expansive waters.