How To Use A Fish Finder

Learn how to interpret and use a fish finder to find and catch more fish!
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Hey, this is Gene Jensen with Today, I'm going to talk a little bit about how to read a depth finder. I'm going to show you a few things that just happen to be right here under the boat and around the boat that might help you guys out when you're out on the water trying to figure out what's underneath. So here we go. I'm going to crank up the motor. I'm going to try to talk over my motor, because I'm going to move around a bit. Now, I hope you can see this.


   I want you to look and see how dark red that bottom is right there. That bottom is absolutely straight rock. It's not hard bottom. It's not anything. It's straight rock. See the big, huge boulders on the bottom and things like that? This little thing right here -- that's a tree laying down right there. It's just softer, not as red, as the rest of it. That right there, same thing. It's a tree trunk that's laying down.


   Now, let me show how to make sure that that is rock. I'm going to go to your menu. You're going to change your lower range to double what your depth is. So I'm going to go 60. I'm going to go -- oops -- well, that's fine. We'll go 90 feet. Now, look, we're going over these rocks and these boulders. See how heavy they are? Right down here is your double echo. That's what I look for, but hard bottom will have double echo, too. So what you look for is you look for a lot of red in that double echo. See how much red that is? That tells me that that's straight rock. If it was hard sand, it would have just a little bit of red in it, a little bit of orange, things like that. See, that's sand in between two boulders.


   This is what your rock and boulders will look like with a gray scale. Dark, dark black, and you got a lot of blacks in here. The softer the bottom, the more grays you'll see, the more grays you'll see up here. The thinner the black line will be, the softer the bottom.


   Look right here. You can see the thermocline really clear right now. Thermocline is right there. Now, if I take my Humminbird and bring that cursor up to right there, and it tells me that my depth is -- cursor's in 19 feet, so your thermocline's 19 feet deep.


   I'm going to talk a little bit more about that thermocline right there. A lot of the cheaper ones actually show it better sometimes if you turn the sensitivity all the way up. But once you know where the thermocline is, what you do with that is -- turn the camera around. What you do with the knowledge of the fact that you know what depth the thermocline is, you start looking for cover and structure at that depth.


   I'd be looking between 16 and 20 feet for rock piles on the end of points, brush piles on the end of points. Just points that are about that deep, things like that, things that'll hold fish on ideal structure. And just crank them, Carolina rig them, it really doesn't really matter. Just throw something that'll cover that area very effective. If there was grass that deep, I'd be fishing grass patches that deep for sure, but there's not. The grass on this lake is stopped -- I guess it grows down to about 8 feet and that's it.


   So, let's see what a tree looks like. Now, there's your tree trunk. Right now we're going over top of some tree trunks. There's one right there. There's one right there. See a lot of the blues and the yellows in it? That's still part of that tree. That's some limbs coming off of that tree. We're going over top of some submerged timber right now.


   Now, let's go see what it looks like in gray scale. It looks like a bunch of fish, doesn't it? But it's not. That's a bunch of trees. Now this right here -- that right there is your bait fish on the top of those trees. Some of it is. Some of those are just part of the tree. We're going to come out of those trees and head back down to the bottom of the river channel.


   This is all sandy bottom or clay bottom, probably clay. Not quite dark red. See how dark red that is? That's beginning to be rock. There's the first boulder. Second boulder. See, all up in here, this is all bait fish, pods of bait fish. Big boulder. Big rise in the bottom, too. See it on the side imaging? All these rocks and boulders. Bait fish scattered around.


   Now, the thing to remember when you're reading a fish finder is -- I really hate to call it a fish finder, because more or less it's a depth finder, it's a structure finder. Very rarely can you find fish in shallow water with a fish finder, because the transducer sends out a signal that's in the shape of a cone, and it's not very wide at shallow depths. So what you're looking for is you're looking for brush, you're looking for rocks, but mainly you're looking for drop-offs and ledges, drop-offs, points where the bottom rises and falls and things like that. That's your ideal structure. Points that are close to deep water or close to the river channel during the summertime.


   Well, that's about all I've got for right now. So like I always say, visit for the answer to all your questions about bass fishing, and have a great day.

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