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Traditional depth sounders

Jul 19, 2019
The Lowrance LST-3800 digital depth and temperature unit is in a class of its own, measuring depths up to 700 feet.

The Lowrance LST-3800 digital depth and temperature unit is in a class of its own, measuring depths up to 700 feet.

Courtesy Lowrance

Traditional depth sounders seem to get short shrift in dockside conversation these days, owing of course to the proliferation of multifunction chartplotters and the array of information they offer to cruisers with fingertip ease. On many boats, standing watch today means shifting effortlessly through full-color screens showing GPS mapping, depth sounder/fish finder, anemometer, radar and other features through an NMEA 0183, NMEA 2000 or open source network.

However, sailors who depend on paper charts and minimal electronics — VHF radio, hand-held GPS and a stand-alone depth sounder — are still making successful ocean passages, blissfully innocent of the compulsion, or ability, to spend big bucks on more elaborate systems.

Just to refresh our memories, a traditional depth sounder consists of a transducer mounted either on the transom or inside the hull near the keel, an analog needle gauge or digital number screen, a cord to connect the two components and two wires to the electrical panel. That’s it.

In the $100 to $200 range, Humminbird, Faria, NorCross and Lowrance offer dependable, traditional depth sounders that are easy to install and use. They all feature weather-resistant digital LCD screens, which you may mount on a bulkhead or other exterior surface for easy viewing.

Humminbird’s HDR 650 detects depths up to 600 feet, making this a particularly good value at around $100. The unit comes with a transom-mount transducer and an LCD display that fits a standard 2.125-inch gauge hole. You may choose from three bezels — white, black or chrome — all three of which are included with each unit. In lieu of the transom mount, you might want to consider either a bronze or plastic through-hull transducer, which is sold separately.

Faria offers a plastic through-hull transducer, which reads up to 54 fathoms (312 feet), but the unit is priced low enough for budget-minded coastal cruisers to enjoy an extra measure of safety. Another inexpensive, entry-level sounder is NorCross Marine’s HawkEye DepthTrax 1B, available with either a transom-mount or hull-mount plastic transducer. The HawkEye features an upper and lower depth alarm system consisting of an audible alarm, a red LED and an LCD message.

Signet’s SL172 is a classic among depth sounders with its round black bezel and simple design, which match the analog SL254 Wind Indicator, SL11 Knotmeter and other devices in this series. The SL172 detects depths up to 200 feet and is available with either a plastic mushroom or bronze wedge transducer. The SL172 with a plastic through-hull transducer on Saltaire has served for more than 20 years, including a circumnavigation, and has been in the shop only once for a rebuild of the gauge.

The Lowrance LST-3800 sounder is available with a transom-mount transducer and has depth capability to 700 feet. The unit also includes water temperature readings, along with shallow and excessive depth alarms, making this a great value at less than $200.

The choice to purchase and install a traditional, stand-alone depth sounder will depend on the specific needs of crew and vessel. Discussions regarding depth sounders, aside from fish finders, always revolve around submerged dangers. While underway on open ocean, you can generally rely on your charts for depth. But what about anchoring?

When I’m looking for my ideal anchoring depth of 20 to 40 feet, my eyes are fixed on the depth sounder, not the chart. If you can measure reliably up to 200 feet, then you can scout around a harbor for a spot to drop the hook for the night. Determine what you actually need in a depth sounder, or fish finder if that is your preference, and choose accordingly.

Circumnavigator-author Bill Morris is the author of The Captain’s Guide to Alternative Energy Afloat and is a frequent contributor to Ocean Navigator.

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