Bow Mount Sonar

The progression of bow-mount sonar.

Photograph with artist's rendering shows the concept: Lowrance's steerable, forward-looking sonar from a transducer mounted on the trolling motor.

Remember the good old days when we didn't have sonar, and we just sort of bumped around the flats or the lake hoping we would run into some fishy spot . . . no, that's right, those were the bad old days, when we were fishing blind. We still caught plenty, to be sure, grace of the sparse populations of humans and abundant populations of fish. But those days are gone, for better or worse.

Now, every boat has sonar, and a lot of flats and bass rigs have sonar at both ends. In fact, for those who fish with a trolling motor, a sonar system up front has become pretty much standard equipment—and some of the bass guys even have a couple of big-screens mounted on the front deck.

All depend on a transducer that's mounted on the lower unit of the trolling motor, or in some cases to a transducer built into the housing of the lower unit. The cable runs up the shaft to the monitor and voila, you can see what's directly under your feet when you're casting from up front. Particularly when you're fishing suspended fish, ledges or rockpiles, the ability to have the transducer almost right under you, rather than a boat-length behind you, can be a big help.

Bow-mount sonar has undergone a rapid progression in recent years, from standard or broadband sonar to down-scan and side-scan, delivering a more photographic image and giving the ability to see what's to the side of the boat, as well as directly below, and within the last year or so, to being able to look ahead of the boat or on all sides at once. Both Lowrance and Humminbird manage the trick by putting a special transducer on the lower unit.

Lowrance calls their version SpotlightScan. The transducer looks wherever you point the troller, out to 150 feet—about maximum casting distance for most of us with typical inshore or bass tackle.

The advantages of these systems for working docks, mangrove shorelines, nearshore rockpiles, channels and weedbed edges will be evident to any experienced angler—you can “look” at your target without putting the boat anywhere near it, and you can immediately determine exactly where any fish or structure is located relative to your position—figuring that out with side scan can sometimes be a little tricky, and with down-scan or traditional sonar, the boat has to be directly over the target to capture an image. (Both downscan and broadband or traditional sonar are also part of this system, though, and you can have a look at all three views at once by splitting the Lowrance screen at the touch of a few buttons, real or virtual.)

The SpotlightScan readout looks much like the readout from scanning-type units—it's more picture-like than conventional sonar readouts, but the relative size of smaller targets—like individual fish—is smaller and requires you to pay close attention to pick them out in most cases. The images are bright targets on a dark screen, available in nine different shadings.

The image displays on Lowrance HDS Gen2 and Lowrance HDS Gen2 Touch models, but if you don't have the new touch-screen models, you also need a “SonarHub” connector. The transducer only, all you need for the Touch models, is $499 including transducer and hookups, while the SonarHub(TM) and transducer package is $999 MSRP.

Humminbird offers an alternative approach with their 360-Imaging, which operates via a transducer that looks all around the boat in a circle up to 300 feet in diameter. The transducer can either be mounted on a separate shaft with one-touch deployment or on a pod attached to the shaft of the trolling motor.

The scan can be set for anything from 360 degrees to 10 degrees; the narrower scan gives a quicker refresh rate, but looks at a narrower window. Anglers moving down a shoreline on the troller likely will use a narrower beam to look ahead of the boat, while those fishing open water, maybe around bait schools, might benefit from the full 360 images. The system, which works with 798ci SI to 1198c SI models, is $1,499.

For more information, visit www.humminbird360.com and www.lowrance.com. FS

First published Florida Sportsman August 2014