For the first five years that I fished out of a kayak, I refused to use a fish finder. This was twenty years ago when fishing kayaks weren’t designed for them, and what was available wasn’t up for the conditions we face in our small, exposed vessels.
Today is a different story. Kayaks are now intricately designed with a fish finder display, battery and transducer well in mind. At the same time, these electronics are now capable of surviving constant exposure to the elements.
What all this means is the fish have nowhere to hide. That is, as long as you know how to read the fancy screen sitting in your boat.
How to Read a Fish Finder
Using a Fish Finder on Deep Structure
All sonar works under the same principle: the transducer sends a sound signal, the signal bounces off fish and structure, and it returns to the transducer. The transducer transfers the signal to digital data that is displayed on the fish finder screen.
Traditional sonar uses a steady cone-shaped signal that covers more area but produces less detail as the water gets deeper. On the other hand, CHIRP sonar uses a variable signal to produce a more detailed image of the bottom, fish, and structure.
While traditional and CHIRP don’t produce the photo-like images of down view or live view sonar, the basic sonar systems beat the competition in deep water. I use CHIRP sonar to supplement my down view sonar. I think CHIRP produces clearer images of fish and provides valuable information about the bottom composition.
What Those Colors and Shapes Mean
For example, on my color-screen fish finder, dark red represents dense structure like rocks or a shipwreck while green or orange might be mud or sand.
Using traditional sonar, I can see I’m over rocky bottom or sand, grass or a reef. Large fish return an arch-shaped mark with a red center. Thick clouds of baitfish look like a red blob with green and yellow outline and big fish appear as red arches.
Viewing the structure and fish in perfect profile produces better target separation. I can decifer a school of small fish from several large fish swimming close together. The traditional sonar even exposes fish hanging on the bottom as lighter colored bumps on a solid line.
When I’m fishing in deep water, I can adjust the gain to produce a narrower sonar cone for more detail on the bottom. Then, I can zoom in traditional sonar to search for fish hiding in structure or on open bottom.
Even if I don’t have money or space for more advanced down-view and forward-facing sonar, CHIRP is available on the most basic systems and provides detailed information on structure and fish to keep me in the game.
How to Use Down-view and Side-view Sonar to Search for Fish
Down-view and side-view sonar are the biggest advancements in sonar technology since CHIRP hit the water. These sonar systems use super high power signals to produce highly detailed three-dimensional images below the boat and up to 200 feet on either side.
Using down view, I see incredibly accurate depictions of structure. A shipwreck looks like a shipwreck, a grass bed appears as squiggly lines and fish show up in life-like detail.
Side-view sonar produces 3D images of the water on either side of the boat. On the screen, the center is the boat’s path. Dark lines down either side of center show water directly below the boat. The bottom stretches to each side and brush piles, jetties, bridge pilings and other structure are depicted piece by piece. Best of all, I can see clouds of bait and single fish hovering in the water.
The Secret Is in the Shadows
The key to reading side-view and down-view sonar is interpreting the shadows. As the sonar signal strikes a fish, it leaves a dark shadow behind the target. With experience, I am able to analyze the length and depth of the shadow to determine the size and depth of the fish or structure.
I use side-view sonar to search for fish. The images are not in real-time. By the time I see fish they are already behind my kayak. Then I turn to 360 and live view to narrow the search.
360-degree Imaging for Pinpoint Accuracy
360-degree imaging is the next evolution in sonar. Like underwater RADAR, the 360-degree transducer produces an image of fish and structure in a 360-degree ring around the boat. The kayak is in the center of the ring. A dark circle around the boat shows the water directly below the boat and the bottom fills the rest of the screen. A depth drop is depicted as a darker color, and a depth rise is lighter. Using the range rings, I know the distance a target is from the boat.
Each sweep of the sonar produces a new image of the fish as they move past the transducer. With 360 sonar, I can watch the direction the fish are moving.
360 sonar works best from a stationary boat, so I use it to track fish and find the range and depth of structure. Once I get the mark zeroed in, forward facing sonar takes over.
Behold Forward Facing Live
Side-imaging and 360 sonar are great for finding the fish, but forward-facing sonar works like an underwater video camera providing a live view in front of the transducer.
I mount the transducer at the end of a pole and lower it below the water. Then I turn the transducer to sweep the beam and capture live images. Using forward-facing sonar, I watch fish react to my lure and adjust my tactics until they respond.
Reading forward facing sonar takes some practice. The images are clear with realistic depictions of fish and structure, but interpreting the signal and using the sonar to its full potential requires experience.
Forward Facing Modes and Reading the Screen
There are three modes: forward, landscape and down. Angling the transducer down below the boat captures real-time images inside a radius around and below you. Forward mode points the transducer to depict targets directly in front of the transducer. For a wide view in an arch in front of the transducer, landscape mode captures a wedge of the water and bottom.
Not only does the sonar provide a directional view of the water around the boat, but the images are in real time so I watch fish swimming like watching my home security camera. Dense structure like rocks and metal produce a dark return while fish or wood and grass appear lighter. And fish marks look like wispy ghosts moving across the screen.
Understanding the numbers on the display is key to interpreting the forward-facing sonar image. A scale along the top indicates the distance from the transducer, while numbers along the side of the show the depth. A boat icon in the corner indicates the angle the transducer is pointing
Objects closer to the transducer show-up clearer so setting the range farther from the boat produces less accurate returns. Adjusting the signal gain increases the sensitivity to compensate for water clarity. Use higher gain for clear water and in dirty water, lower the gain until the interference disappears from the screen.
Other Important Information on the Display
In addition to images of fish and structure below and around the boat, a fish finder provides other valuable information to help me catch fish.
Water Temperature
Water temperature is one of the most important aspects for finding fish. Most fish finders include water temperature read out on the display screen. When I know a species’ water temperature preferences, I can find the water that holds the fish. Also, understanding how fish respond to a water temperature range allows me to choose the best tactic.
Split Screen
I often use my fish finder in split screen mode. This feature allows me to see several sonar views and my navigation charts together. I often split the sideview or CHIRP screen with a flasher for a real-time view of fish and structure directly below the kayak.
Putting Together the Complete Naval Station
To search for fish, I use side-view sonar. When I find action, I switch to forward facing in forward mode to zero in on the bite. The best kayak fish finders are compatible with all the latest transducer technology, so I can switch among these sonar modes to match the situation.
I never would have imagined myself using all of this tech on my kayak two decades ago. Now I have two screens and two transducers on a boat designed to accommodate a full electronics suite. My kayak’s shallow draft and super silent propulsion, combined with a high-powered fish finder and GPS put me on fish I would have forever missed.
Side scan sonar picks up targets to the left and right of the boat so I can search a large area for fish and structure. | Feature photo: Roberto Westbrook
