Watching your wheel wash, observing supply boats, and watching for hints of clear water boiling up around a rig are all great ways to figure out where clear water hides underneath muddy water.
However, finding the exact depth of this layering is best done with a highly tuned depth finder.
Capt. Tommy Pellegrin accomplishes this by turning up the gain on his Lowrance units high enough that he starts seeing lots of stuff he doesn’t normally want to see.
“If you want to just see the fish, you slack off your gain where you can just see their air bladders,” he said. “Say that’s normally 40 on your unit. To find the thermocline, jack up your gain maybe all the way to 80 until you start clouding off your screen.”
Once his Lowrance screen gets full of all kinds of blues, greens and yellow, Pellegrin begins to notice in the middle of all that color maybe some red dots that are all in a line at the same depth.
“It’s definitely not distinct, but those red dots show the temperature difference at the thermocline,” he explained. “It’s not going to be a fine line like if you’re tweaking your unit to find the bottom. It’s kind of like the snow on an old television set.
“In all that clutter, there’s one little zone where it’s thicker.”
