Adaptations to fishing sometimes travel slowly. So it has been with the downrigger. These unique angling devices have been helping freshwater fishermen make their catches for decades in the Great Lakes, where big fish means deep water. Down rigging is simply controlled-depth trolling so that the fisherman can place the lure at precisely the depth desired, usually the depth indicated by concentrations of signals from the fish locator. This method lets a lure or bait get to depths impossible for regular casting or trolling and does it with exacting accuracy. Downriggers are marketed in numerous brands models and price ranges to suit the needs of just about any type fishing, from stripers to walleye to black bass. Basic design includes a winch, either manual or electric, a short rod or boom, a heavy metal weight and 100 to 200 feet of small diameter steel cable or stainless steel wire. That is the basic downrigger, a lead weight shaped like a ball or torpedo on a steel wire that is raised and lowered with a reel-type winch, hand cranked or electric. Oh yes, the wire is calibrated so that you tell exactly how deep the weight is lowered and running. This can be measured by turns of the crank or by a metering device that measures the length of wire let out. So how do you fish with a lead ball dragged through the water? The added finesse devices make it a fish catching machine. The weight is attached with a four- to 10-inch line that has a release device that works on the same principle as a clothespin. It clips onto the line from a regular rod and reel and pops loose to separate the line lure and hopefully fish from the downrigger when the drag or pull becomes too great like when a fish grabs the lure and is hooked. Here is how it works: The angler baits a line on a rod and reel with an artificial lure or live bait. The lure or bait is let out 20 to 50 feet behind the boat, depending on the type of lure. If it is a bait that runs level, as opposed to a diving lure, it will be rigged farther back. A diving lure will run a predictable depth below the downrigger ball, based on how much extra line is paid out. To recap, the line and lure is behind the boat, next the line is clipped to the release device and the downrigger is lowered to the desired depth. The angler can hold or place the rod and reel in a rod-holder. Finally the bow, or slack, is eased out or the rod and reel line so that it is running nearly parallel to the downrigger wire. Now it is up to the fish. When a fish strikes, the shock of the moving lure will usually set the hook and the extra drag makes the line snap loose from the release clip and the downrigger wire is quickly reeled out of the way of the fight that takes place, just like any fishing adventure. Downrigging for stripers was probably one of the first serious applications of these devices in Kentucky, though some anglers have been using them for various types of fishing for much longer. On striper lakes nowadays downriggers are a common tool. Other lakes, where the big hybrid bass are popular, the downrigger is becoming a method of choice for fish as well. The riggers are especially deadly in the times when fish hide or suspend in deeper waters out of reach of more conventional methods of fishing. The downrigger has also overcome some weather problems. In winter, the cold will often freeze in the guides of rods and make casting virtually impossible, so that trolling is the only workable solution if you want to keep fishing. The downrigger has a minimum of line handling on the troll with less tangling than planers and sinker trolling. If the wind kicks up on big lakes like Cumberland, Kentucky and Barkley, the toss and swell can make regular fishing impossible. As long as you can maintain safe operation of your boat the downrigger will ride the rough water like no other device. This has been proven for many decades on the Great Lakes, where swells of four to six feet are still fishable with downriggers.   On the hunt, an angler will cruise possible areas where fish have been known to hold, reading the bottom with a fish finder, either a screen or charting model,, to locate a school or group of fish that might be catchable. Marking the spot with drop markers or a GPS, the boat will turn and start a path over the school with the downriggers and lines in place. Several passes will tell the story. With a GPS, anglers are now plotting a course between schools or following a particular type of structure with precision. Differences in the contour of the bottom make the differences in where fish hold. Structures like edges of river channels, submerged points and humps, ledges and drop-offs sunken roadbeds are prime structures. With a good charting locator and a GPS, gullies and ditches or a stump bed or even a small rise or dip in the bottom that holds fish can be remembered and revisited. The longer runs between schooled fish means less turning and that means more potentially productive fishing time on the water.