Troll Speed Indicator - Unaffected By Wind Or Wave Action

No batteries required. Accurate within 1/10 of a knot. Easily control speed so lure is at optimum performance. Easily fits most boat hulls even sail boats. Reads both knots or mph (miles per hour) unaffected by wind or wave action. Corrosion-resistant construction. Heavy 16 ounce. Ball. Within your fisheries, you'll find sweet spots in troll speed for all your applications, and with precise measurement, you can fish more effectively, more often. Speed measurements via on board electronics leave a lot to be desired. Gps "speed over ground" measurements do not account for the effects of tide and current flow on lure action. The luhr speed troll speed indicator operates on a simple, mechanical measurement of speed that accounts for the exact conditions your lure is running in. Measuring accurately to within 1/10 of a knot, precision control can be provided to all your presentations. Many anglers customize the large readout dial with tags to highlight target speeds for specific lures and/or techniques. More accurate & costs less than electronic fish-finder speedometers! Corrosion- resistant construction for fresh and saltwater use.