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December 17, 2012

Sounder Sizing

The Power to Depth Equation

Beyond Power

Sounder-power issues change when the topic turns to Broadband and CHIRP units.

Lowrance/Simrad’s BSM-1 Broadband module generally uses about 200 watts of power and has recorded depths to 5,000 feet, Edmunds says. “It changed the way a traditional sonar works. Instead of focusing power into the water, it’s filtering and looking at the smallest signal returns.”


garmin gps map
(1) Garmin’s GPSMAP 546s multifunction display pairs with (2) a 600-watt transducer. Garmin’s GSD 26 CHIRP sounder module (3) pairs with a transducer (4) that generally measures more than a foot long. Above right: Simrad BSM-1 broadband sounder module (transducer not shown.)

In order of price and performance, Edmunds says, a sounder lineup would go something like this: 600-watt, 1 kW, BSM-1, 2 kW, 3 kW, CHIRP.

Garmin, Lowrance/Simrad and Raymarine all market recreational CHIRP sounders. Furuno currently sells commercial-grade CHIRP gear.

Kiburz says Garmin’s GSD26 CHIRP unit uses anywhere from 300 to 3,000 watts. CHIRP, which sweeps through a broad range of signal frequencies, can operate at lower power and still achieve depths — up to 10,000 feet in some cases.

In the end, for most anglers, choosing a fish finder and transducer comes down to price plus vessel and fishing style. Competitive captains often find that the higher-priced fish finders pay off at the scales. On the other hand, you’ll never catch me saying weekend anglers aren’t competitive.