How to Read a Lowrance Fish Finder?

George Hanson
George Hanson
Research Writer
A successful journalist and news reporter in the past, George is now focused on freelance work to be able to dedicate more time to the most important things in his life: fam read more
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John Carson
John Carson
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John is an avid traveler, hiker, and RVer. Moreover, it seems like he knows everything when it comes to fishing and hunting: his father started sharing all the tips and tric read more
Last updated: August 26, 2023
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Lowrance fishfinders provide boaters, anglers, and anyone on a fishing trip with information on everything underneath their boat. Aside from fishing, fish finders are very functional devices as they give boaters some useful data concerning the locations of rocks, logs, and other obstacles that may cause boat mishaps.

Like every other device, getting the proper model is not enough to become a successful angler. You have to know how to use and how to read Lowrance fish finder. In this article, we will see how to identify fish by checking outlines and icons on the display screen.

How Lowrance fishfinder works

How to Read a Lowrance Fish Finder?

The fish finder sends an ultrasound wave directed downwards in the form of a cone, according to a predefined frequency. When the ultrasound wave hits an underwater object like a fish or just the bottom, some of the sounds are reflected and sent back to the transducer. This then acts as a receiver and transmits the return echo to the sounder, where it is converted and amplified.

The returned echoes are analyzed and displayed on the sonar screen. We thus obtain on the screen a sort of two-dimensional representation of the relief of the background and the objects.

What sensors can tell you?

The device offers a great source of information since it gives a boater an idea of ​​the relief, the nature of the bottom, the presence or absence of fish, their characteristics, etc., and this even works at great depths.

The objects found in the sea, which are the fish or the materials that make up the seabed, have a certain density. The sensors return information in the form of sound waves. Next, this information shows a difference in the density of objects hit by the waves through the returned echo.

In case of fish, for example, those have a bone or cartilaginous structure, which gives them different densities. As in the anatomy of a fish, there are organs with different densities. The first organ that the sensor detects is the swim bladder. Subsequently, it detects the rest of the organs and tissues.

Depending on the intensity, shape, degradation with which the echo has been returned, and by taking into account the different anatomy between fish, we can therefore interpret what type of fish it is.

What do colors and echo return strength show?

Like all fish finders on the market, Lowrance models come in black-and-white or colored display screens. Thus, they show final images in colored forms or monochromes.

The color of the lines and icons show the strength of the echo return. The color is shown depending on how strongly the echo returns on the transducer. Here, the density and hardness of the lines and icons are the most important factors that help you interpret the object shown.

To explain how the returned echo as a function of density works, let’s imagine that we have in our hands a tennis ball. And in front of us are several walls – one of which is made of concrete, another made of wood, and the last one made of rubber.

If we throw the ball against the concrete wall, the ball will bounce back intensely, almost so much that its bounce will reach near its launch point.

If we throw it on the wooden wall, the ball will bounce back from the target point but not as far as the one that hit the concrete.

And when the ball is thrown at the rubber wall, it will absorb the blow, and its rebound power will be very small and very far from the launch point.

With sound waves, we can find something very similar to the analogy made above. It depends on what material they find on their way.

The more hard or dense the material against which the signal bounces is, the greater the intensity of the bounce will be, and the faster it will return.

Fish ID technology

Lowrance fish finders make use of the Fish ID technology in detecting fish underwater, as well as the materials. The technology converts raw data from the water bottom into a user-friendly display interface. Depending on the fish seen and the features beneath the water, the technology comes up with different icons on the display screen.

On Lowrance screens, lumbers or growing trees will appear in the form of vertical lines. Meanwhile, the icons representing aquatic vegetation are thick and well pronounced.

How to read a Lowrance fish finder screen

To know how to read Lowrance sonar fish finder, go through the following processes.

  • Turn on the fish finder by pressing its power button. Ensure the device is in automatic mode and that the alarm function is switched off.
  • Then focus on its full screen to see what the fish finder shows. Keen an eye on the digital information on the display screens. One of the readings that will appear on the screen includes the water depth. This is displayed in foot measurements. You can also find information on the speed of the boat as well as the temperature of the water.
  • Check the lower part of the display screen. You’ll find an extending line joining the two sides of the screen. The line is a representation of the ground of the river, lake, or reservoir on which you’re boating. Below are what each line signifies:
    • Dark and dense line: The line will appear very dark and dense if the ground is rocky or consists of any other hard material.
    • Light and thin line: Conversely, if the bottom is soft, the line will be light and thin.
    • Flat line: If the line is flat, then the ground in the water is flat.
    • Uneven line: If the line has declined and slopes, this shows the bottom is uneven.

  • Next, take note of the objects above this line. Doing this will let you know the types of objects you have on the water bottom.
  • To search for fish, check between the lines at the upper and bottom parts of the screen in the water column.
  • The bigger the icons are, the bigger the fish will be. To know where the fish is, take note of the details in the water column. This way, you’ll know whether they are at the bottom of the water or above the vegetation or timber.

Fish finder tips

The transducer transmits signals in the water back to the fish finder. So ensure it is placed to the fish finder as close as possible.

Seaweed bottoms are very difficult to detect. This is due to the high water content of the algae, which makes it difficult to scan through. Only the most fibrous ones and with lower water content are detected. Usually, a seaweed or mud bottom returns the same echo. The stone, gravel, and gravel bottoms return a similar echo and are made up of objects with a size between 2 or 3 mm and 200 mm. Mud particles are smaller than 0.1 mm. Fine or coarse sand is made up of objects between 0.1 mm and 2 mm. And rocks are made up of objects larger than 20 cm.

Due to its hardness, the rock bottom is considered by an image with fine, sharp, and well-defined lines of the irregular or broken shape.

On a sandy bottom, the particles have a dimension between 0.1 mm and 2 mm. On the fish finder screen, we will see a wide and smooth surface of darker color at the top with very little degradation in the lower area.

What about Insight Genesis?

How to Read a Lowrance Fish Finder?

Insight Genesis is a technology that lets you create your maps from the sonar data you’ve recorded. You will be able to include precise 30cm high-resolution contours, bottom hardness, and even lines of algae!

Insight Genesis enables you to create and update your cartography with Lowrance, Simrad, and B&G equipment.

It allows you to generate custom maps using Broadband sonar data from your Lowrance equipment along with information from StructureScan transducers.

The tool offers boaters the ability to create custom contour maps of their favorite fishing and boating areas. It helps you map uncharted waters or ensure that the information on already surveyed waters is accurate and current. Since it allows us to have all the information on the bottom vegetation, this is widely used for cartography in inland waters.

Final word

Knowing how to read a Lowrance fish finder is another hurdle you must get past after purchasing the equipment.

By reading what is on the screen and taking note of the type, density, and hardness of the lines, you can tell what objects are fish, sea vegetation, rock, and other water features.

On a color screen, the density captured by the waves will be interpreted in the form of color intensity. In a monochrome screen, it will be shown in different grayscales.

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