Thin Film Transistor (TFT) screens

TFT color units do consume more current, though. Glorvigen got about six to seven hours from a rechargeable 7-amp battery; but he feels that the TFT screen helps him to better visualize what's happening under the ice, just as it helps him see what's happening under the surface in open-water fishing. He uses the split-screen graph mode rather than the flasher mode, as it also provides a zoom screen on the left, enabling him to see the bottom in 25 to 50 percent of the water column. On the right side is a full-screen view, surface to lake bottom, which enables him to see suspended fish or baitfish.

Glorvigen likes the "history factor" associated with TFT screens, too: Information displayed as "current" 5, 10, or 15 seconds ago remains on the screen for a time. He reports that while ice fishing on Lake Winnibigoshish on a 30-foot break, he hooked a walleye, brought it up, removed the lure, and then happened to look at his TFT screen. It showed another fish at 18 feet just a few seconds earlier. It had moved in and then out again while he was unhooking the first fish. Scott immediately put his lure back into the water and caught the second fish. With a flasher, he says, he never would have known the second fish was there, since a flasher can't display history.

According to Glorvigen, color adjustment is especially important, as it helps to determine signal strength. In the Lowrance scheme, this adjustment is referred to as Colorline. Sensitivity and Colorline can be adjusted independently. Glorvigen first chooses the appropriate sensitivity level, then sets up his color system so that the lure color on the screen is black or blue. This feature provides more flexibility for both sensitivity and color selection, which means that, in almost every situation, the fish is a different color than the lure.

If a fish is at the edge of the cone and moves to the center, the color changes to a brighter color. A stationary fish in the cone looks like a horizontal line. If the line begins to move up, it could mean it's swimming more towards the center of the cone. (A sonar unit tells you how far a target -- in this case, a fish -- is from the transducer, which is rarely the same as depth.) Of course, it could also mean that the fish is actually rising in the water column. When it's holding tight to the bottom, the fish may appear as a line on the bottom; and if the fish is on or near the bottom, the line may also appear slightly below the edge of the bottom display.

Yes, there's a learning curve involved here. With TFTs, it's in reading and interpreting what the unit is showing you. Most of us learned to use flashers, moved from typewriters to computers, and from slide rules to graphing calculators . . . all of which makes life more fun.

Ice anglers may already have a TFT unit on the boat, just waiting to be tried this winter. Or, maybe they're thinking about buying one before the ice sets in. Just another exciting new way to enjoy fishing this winter. n

*Bill Diedrich, Minnetonka, Minnesota, is a longtime contributor to In-Fisherman publications on electronics topics. He also serves as the Electronics Doc, answering common questions on In-Fisherman's website. Click here to view his column.