Before commiting to a long drop and arduous retrieve, when you decide to drop a bait down several hundred feet you want to have some idea of what’s down there. What you see on your fishfinder often means the difference between just fishing, or catching.

Captain Ralph Delph of Key West uses conventional gear to fish depths as great as 700 feet. With the right bottom machine, he says it’s possible to target individual fish at these depths. “We can watch our jig descend, and the fish rise to the jig,” said Delph, “and that’s when I tell the angler to get ready.”

A fishfinder with a 200 kHz (kilohertz) transducer may read bottom as deep as 1,000 feet if the unit has enough transmitting power, but the fish-marking ability of a 200 kHz transducer in water deeper than 600 feet is marginal at best. Lower frequency transducers record better target definition at greater depths. This is why savvy deepwater anglers opt for a 50, 38 or even as low as a 28 kHz transducer. Delph has four transducers, one with a special narrow beam that allows him to mark individual fish easier.

How deep a transducer reads depends on several factors including power output (watts), transducer frequency, mounting location and boat speed, as well as some factors beyond our control, such as water conditions and seafloor composition.

If you want exceptional detail at 1,000 feet or more using a 200/28, 200/38 kHz, or a narrow-beam transducer, you need to be sitting down when writing your check. Some of these systems cost upwards of $1,500.

Below is a brief sampling of deepwater-grade fishfinders. Many of the units are network systems which can multi-task, displaying charts, radar, weather radar and other features. Prices shown are manufacturers’ suggested list price and are not necessarily the price you will pay. Due to the multitude of mounting conditions, transducers are sold separately for nearly all of these units.

FURUNO

With several new features, the Furuno FCV1100 color video sounder allows users to choose a variety of frequencies as well as several power settings to suit different transducer situations. The FCV1100 is a high-performance, dual frequency fishfinder that allows you to select from 28, 38, 50, 88, 107 or 200 kHz transducers that will read the bottom in water far deeper than you will want to fish.

Furuno FCV1100

Featuring a 10.4-inch TFT LCD screen, the FCV1100 can display echoes in 8 or 16 colors (user selectable) or use a custom color menu to blend colors giving you the ability to display more than 4,000 colors. In addition, a water temperature alarm will alert you to changes in temperature, and the background color can be changed for optimum day or night viewing.

Power is one of the FCV’s strong points, with user-selectable output of 1, 2 or 3 kW (1,000, 2,000 or 3,000 watts), and two transducer frequency outputs. With eight user-selectable and adjustable range scales to 6,000 feet, the FCV1100 can also be custom preset to read depth ranges to 12,000 feet depending on transducer selection. With this unit you also have the ability to display an A-Scope, and to display single, double or triple pictures on a horizontal or vertically split screen. Suggested retail price is $3,595. For more information, visit www.furuno.com or call (360) 834-9300.

GARMIN

The Garmin 3010C is a multi-function unit that requires the addition of the company’s GSD 20 sonar module, a proprietary “black box” sounder add-on that offers 500 watts of RMS power to a 50/200 kHz transducer. Although 500 watts RMS power would be the minimum amount of power needed to display a reliable outline of the bottom beyond 1,000 feet, with a properly installed transducer transmitting on 50 kHz, the 3010C’s 10.4-inch display is a beautiful screen to look at.

Garmin 3010c

The GSD 20 sounder module sends data to up to two Garmin display units, handy if you have a remote display. Other features include auto-ranging (to 2,000 feet), 2X and 4X enlargement, auto and manual zoom, optional fish symbols, and “See-Thru” technology that separates fish from thermoclines and structure.

A bonus to the Garmin 3010C is that it is first a GPS and chartplotter, and second a sonar/fishfinder, so all of the GPS and chartplotting ability is already included prior to adding their GSD 20 sonar module. Suggested retail price of $3,124 includes the optional GSD 20 sonar module ($267.00). Visit www.garmin.com or call (800) 503-7099.

HUMMINBIRD

The Humminbird 931c DF is a user-friendly fishfinder with dual-frequency sonar operating on both 50 and 200 kHz frequencies. The 50 kHz option is capable of reading the bottom in excess of 1,000 feet.

Humminbird 931c DF

Putting out a whopping 1,000 watts for a relatively small, 7-inch display unit, the 931c DF has a maximum stated range of 2,500 feet. There are numerous options for depth-range settings, depending on whether you want to view the water column from the surface to the bottom, or the bottom plus any amount of water above the bottom, or any combination thereof.

Humminbird is the only manufacturer listed here whose fishfinders come standard with a transducer. One possible glitch, though, is that Humminbird only offers a transom-mount transducer for the 931c DF, which may not be a viable mounting location for some saltwater boats. Suggested retail price is $1,200. Visit www.humminbird.com or call (334) 687-6613.