By Paul Lebowitz

Installing a fishfinder adds a new dimension of information to a kayak angler. More accurately called sonars, the lower-cost fishfinders most kayakers choose are best at providing water depth.

If we pay attention to the fishfinder while we are moving from place to place, we can pinpoint productive structures such as drop-offs, holes, and rock piles. After a bit of practice the jumbled squiggles on screen start to make more sense, allowing us to discern whether the bottom is soft sand, vegetation, or rock. Fishfinders may also be used to identify bait fish schools, thermoclines, or somewhat less reliably, individual gamefish. 

Adding a fishfinder to a kayak is fraught with obstacles. Constant spray and splash push the units to their limits. Post-fishing maintenance is a must to head off corrosion. And then there’s the question of where to put the sonar transducer (the puck).

A shoot-through installation is the cleanest way to go. The puck is mounted internally, directly on the inside of the hull. Unfortunately, the souped-up plastics most kayaks are molded from somewhat degrade a sonar’s resolution. Plastic kayaks bend while in use, which leads to another compromise. To keep the transducer from popping off, many kayakers use flexible silicon-based epoxies such as Marine Goop, further hindering the signal.

How bad is it? Not all that much, although those who want to wring every last foot of bottom-scrying performance should opt for an exterior suction cup mount or some sort of scupper hole bracket.

To get the best of both worlds, Mark Ezell of Hook 1 Kayak Fishing Gear has developed a hybrid shoot-through installation method. He demonstrated it with a Lowrance X67C, a compact full-color unit with powerful 800-watt peak performance capable of reading the bottom up to 600-ft down.

“First, find the flattest area inside the bottom of your boat,” Ezell said.

THE TRANSDUCER 2-STEP – By using slow-cure 2-part epoxy as your transducer adhesive, you’ll avoid the pitfall of lost signal strength. If it pops off during future use, glue it back down using a thin bead of a flexible fast-cure epoxy such as Marine Goop. PHOTO COURTESY HOOK 1 KAYAK FISHING GEAR

It should be out of the way of any gear typically stored inside the hull. For instance, to keep space clear for stashing rods during surf transits, Ezell might hide a puck behind a scupper post.

Here’s where his technique differs from the Goop it and go method.

“I build a moat around the outline of the transducer using plumber’s putty. Fill it halfway with 2-part slow cure epoxy, then twist the transducer into the puddle and weigh it down with a rockcod sinker,” Ezell explained. When the 2-part epoxy dries it will be rigid and won’t rob any juice from the signal.