July 30, 2011
By In-Fisherman
Liquid Crystal Displays (LCDs) are sometimes called passive matrix screens. The drawback is in their performance, however, in cold weather. If LCDs start out in a warm environment, they work well down to about 15F; but when the unit is left in the cold for a time, the liquid in it reacts with the consistency of molasses. This creates slow screen responses and often makes the unit ineffective for ice fishing.
TFT screens are called active matrix screens and are not affected by the low temperatures ice anglers usually encounter. Their screens are constructed differently, with an extra layer of transistors connected to the LCD panel, one transistor for each color pixel (red, blue, and green). These transistors drive the pixels and eliminate the problems of slow response and ghosting common to traditional LCD screens. The additional transistors generate heat -- a bonus for the cold-weather angler, because it keeps the screen functioning.
Lowrance Electronics has tested their TFT screens to minus 32F with no decrease in performance. And when properly engineered, TFT screens produce wide viewing angles, vibrant color, and minimum washout in direct sunlight. The changes brought about by the TFT technology, along with faster processors, increased sounding rates, and fast scroll rates for the screens, have produced technically efficient units.
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Most TFT screens should provide fine performance for ice fishing. The Ice Machine, for instance, marketed by Lowrance Electronics, is available in X-67c sonar or X-68c sonar/GPS. Each is a complete ice-fishing package, including a power supply, charger, carrying case, and a transducer designed for ice fishing.
Lowrance includes some special features when the machine is placed in Ice Machine Mode, which changes the way incoming sonar echoes are filtered, and reduces some of the surface clutter caused by ice and water. In Ice Flasher Mode, the normal 256-
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color display is reduced to a few high-contrast colors. Another feature called Colorline helps the angler distinguish between weak and strong signals. Weak signals appear on the screen as dark colors such as black or blue, while strong signals appear as bright colors, such as red or yellow. Display Screen choices include both full and split screens.
Anglers who already have a sonar unit with a TFT screen can create their own ice-fishing packages. You need a 12-volt power source, usually a rechargeable battery and charger, and a transducer system that allows for adjustment to ensure it's hanging vertically in the water. I've seen a variety of locator or battery boxes with a mounting bracket for the sonar head attached to the top of the box. This adaptation, with the proper bracket, allows for the use of any size sonar unit the angler may have.
Scott Glorvigen of Grand Rapids, Minnesota, a professional walleye angler and avid ice fisherman, used an LMS 330 for his ice fishing last year. He placed it in the softpack carrying bag and attached the GPS module to the top of the bag, which gave him the additional benefit of GPS. Using an accurate map cartridge such as the Lowrance LakeMaster ProMap card allowed him to accurately position on a piece of structure.
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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.
