Modern boat fishing has long ceased to be simply guessing where to park a fish by the appearance of the water. sounder It's become an indispensable tool for looking underwater and seeing what's hidden from human eyes. Many fishfish are wondering how it converts invisible signals into a visually understandable image on a screen, and why screen footage can be so different from reality.
Understanding the physical processes inside the device will help you not just follow the readings blindly, but analyze the situation. Hydrolocator It sends out a sound pulse that bounces off objects and comes back, creating images of the bottom, the topography and the underwater life. In this article, we'll go into detail about the mechanics of the process so you can use it effectively. video-analysis To find trophies.
The biggest mistake for beginners is to think of the sonar screen as a window into the underwater world in real time. What you're actually seeing is a graph of history where the horizontal axis is time and the vertical axis is depth. That's why static is often misleading, and only the movement of the boat allows you to build a full-fledged image. echogramSo let's see how we interpret this data correctly.
Physical Basis of Echolocation Underwater
The principle of operation of any sonar is based on the propagation of sound waves in the water environment. ConverterThis wave, often called a sensor or a "tranduser," generates an electrical pulse that is converted into a sound wave of a certain frequency, and it travels from surface to bottom, encountering various obstacles in its path: rocks, driftwoods, thermoclines and, of course, fish.
When a sound wave collides with an object with a density other than water, some of the energy is reflected back to the sensor. Receiver It picks up this echo, and the processor calculates the distance to the object based on the time of the signal delay. The speed of sound in the water is approximately 1,400 meters per second, which allows the instrument to accurately determine the depth and position of the targets.
It's important to understand that different frequencies behave differently. 50 kHzThey have a greater penetrating power and cover a wide cone, but they give a less detailed picture. 200 kHz or 455 kHz HD-DownVision systems provide detail comparable to photography, but work at lower depths.
⚠️ Attention: The speed of sound in the water varies with temperature and salinity. If you have moved from a fresh lake to a salt sea, be sure to calibrate the speed of sound in the instrument menu, otherwise the depth readings will be incorrect.
The cone of radiation is another critical parameter. Imagine the light of a flashlight pointing downwards: there's a signal in the center of the beam, and it's fading at the edges, and the fish passing through the center of the cone will be displayed as a large arc, and the same fish at the edge of the cone may be barely noticeable or lost. Viewing angle It directly affects the width of the scanned strip of the bottom.
Interpretation of the image on the sounder screen
When the signal returns, the processor color it in different colors depending on the strength of the reflected pulse. A weak signal is shown in blue or blue, the middle one is yellow or green, and a powerful one, reflected from a solid object, is red or black. color-pattern It is the key to reading the underwater landscape.
The bottom is displayed in a wide colored stripe at the bottom of the screen. A solid rocky bottom will give a powerful signal return and will look like a thick red or black line. A illithy or soft bottom will absorb some of the energy, so the stripe will be thin and painted in blue or green tones. The fish will be displayed as arcs, the shape and size of which depend on how the fish passed through the radiation cone.
Thermocline, or water layers with extreme temperature changes, often look like horizontal bands hovering in the water column. In these areas, fish can accumulate because plankton are often concentrated here, but inexperienced users can mistake the thermocline for a fish joint or, conversely, skip it, considering it a hindrance.
- 🐟 Fish arcs: The classic symbol of a fish passing through a sonar cone, the wider and brighter the arc, the larger the object.
- 🪨 Bottom relief: The change in thickness and color of the lower line indicates the structure of the bottom (silt, stone, gravel).
- 🌡️ Thermoclin: Horizontal band, often intermittent, indicating the boundary of water layers of different temperatures.
- 🌿 Algae: Vertical stripes stretching from the bottom upwards, often with "ragged" edges.
Modern models such as Garmin or LowranceThey use noise-reducing technology to clear the image of interference, but sometimes the noise can be small fish or a suspension, so you don't have to rely on automation.Sensitivity) allows manual adjustment of the weak signal display.
The impact of settings on picture quality
Factory sounder settings are rarely ideal for specific fishing conditions. Automated mode often strangles weak signals as interference, or conversely fills the screen with snow from air bubbles. Manual adjustments are needed to produce a quality image that can be analyzed from video or real time.
The first step is to adjust the depth range (RangeIf the device automatically sets a range of 0-100 meters, and you catch 5 meters, you won't see the details. You will manually set the upper limit just above the water level and the lower one just below the bottom, which will stretch the picture vertically and make the objects more visible.
Use Zoom to study the bottom layer in detail, zooming in 2-4 times to see how the fish reacts to your bait in real time.
Screen refresh rate (Screen Update) or scroll speed (Scroll Speed) They also play an important role: When the boat is moving slowly or when it is drifting (anchor fishing), the standard scrolling speed will stretch the image, and the fish will look like long sausages. Increase the scrolling speed to compress the picture and restore the real proportions of the objects.
⚠️ Attention: At high speed boats (>10 km/h), the sensor may start to detach from the water flow (cavitation), which will lead to loss of signal, in which case lower the sensor deeper or slow down the speed for proper operation. echolocation.
Color palette adjustment (Color Line) helps to highlight fish against the bottom. White Line The bottom is white, and all the objects above are colored, making it easier to visually separate the fish from the bottom, which is especially useful when catching predators in the bottom layer.
Types of sensors and scanning technologies
The evolution of sonars has led to different scanning technologies, each with its own advantages: the classic two-dimensional sonar shows a slice of water directly under the boat. This is great for determining depth and fish availability, but it gives little information about the structure of the bottom around.
Technology DownVision (low frequency down scanning) and SideVision (side scanning) uses high-frequency beams to form an image similar to aerial photography. DownVision shows a detailed picture of the bottom under the boat, allowing you to distinguish between individual rocks, driftwood and even types of bottom vegetation. SideVision scans a strip up to 100-200 meters away from the boat, helping you quickly find eyebrows, dumps and sunken objects.
What is the difference between CHIRP and a conventional signal?
CHIRP (Compressed High-Intensity Radar Pulse) technology sends more than one frequency pulse, a range of frequencies. This allows you to significantly improve the separation of targets (a fish standing close to the bottom will not merge with it) and increase sensitivity without increasing the power of the peak signal.
Three-dimensional sonars and livescope sonars represent the pinnacle of evolution, allowing fish to be seen in real time, tracking their movements relative to bait, a revolution in spinning fishing, although such systems require serious training to interpret the data correctly.
| Technology | Frequency | Coverage | Best application |
|---|---|---|---|
| 2D Classic | 50/83/200 kHz | Cone under the boat | Definition of depth, availability of fish |
| DownVision | 455/800 kHz | Underboat strip | Detailed structure of the bottom, snags |
| SideVision | 455/800 kHz | Up to 240m sideways | Search for eyebrows, dumps, sunken objects |
| LiveScope | High. | Real time. | Spinning, bait wiring control |
The right sensor depends on the type of boat and fishing style. For trolling, the ideal solution is a combination of classic 2D and side scanning. For fishing in plumb or anchor on the river, detailed DownVision and high vertical resolution are more important.
Practical aspects of installation and installation
The quality of the image depends on the correct installation of the sensor, if the sensor is set too high, it will capture air bubbles, causing interference, if too low, water resistance and risk of damage will increase, optimal position - the lower edge of the sensor is 3-5 mm below the plane of the keel or bottom.
When installed on a transom, it is important to ensure that the working surface of the sensor is tightly contacted with water. The air layer completely blocks the signal. For plastic boats, there are special insertion sensors that are glued from the inside of the board, which eliminates the risk of damage when hitting an obstacle, but requires careful selection of space without air bubbles in the fiberglass structure.
☑️ Verification of sensor installation
The cable must also be carefully laid, it must not be tensed, it must not sag into the water, use plastic clamps or special clips to fix, the entry of the cable into the boat hull must be sealed with silicone sealant to prevent water from entering the boat.
⚠️ Warning: Never cut the sensor cable! Unlike conventional wires, the sonar cable has a specific capacity and resistance, and shortening or building it will disrupt the coordination, causing signal loss and burning of the processor unit.
For outboard boats, it is important to consider the plane sensor. Vibration and turbulence from the propeller can disrupt the signal. In such cases, it is recommended to use remote sensors on a separate bracket, retracted away from the flow of water, or cut-in sensors in the bottom.
Analysis of video recordings from the sounder screen
Watching sounder video is a great way to learn, but when you look at someone else's video, you have to consider the context: the speed of the boat, the sensitivity settings, and the type of bottom, and what looks like a huge joint in the video may actually be just echoes of thermocline or bubbles of methane from the bottom.
Now, if you look at the dynamics of the change, if the boat is standing and the fish is moving horizontally across the screen, it's probably a drifting thermocline or a current carrying algae, and real fish rarely move at a constant speed strictly horizontally in static mode.
To learn how to analyze video, compare a sonar image to a real catch. Did you catch a perch? Look at what it looked like on the screen a minute before the bite, and that's the best way to calibrate your visual perception.
When analyzing the recording, pay attention to the tails and plumes. Often the fish, frightened by the boat, goes to the side, leaving a characteristic mark on the screen, and the ability to read these tracks helps to understand the direction of the jamb and choose the right place to throw.
Modern sonars allow you to save screenshots and videos directly to the memory card, which is a useful feature for later analysis of catch points. You can go home, slowly scroll through the recording and study in detail the bottom relief, which at high speed boats could not see.
Why does the fish look like an arc on the echoer screen?
The arc is formed because the distance from the sensor to the fish changes as it passes through the cone of radiation. When the fish enters the cone, the distance is large. When it passes under the center of the sensor, the distance is minimal (the arc top). When it moves away, the distance increases again. As the sonar draws history, this distance trajectory forms an arc.
Can the sonar show the kind of fish?
A conventional sonar does not show a fish, it only shows the presence of a solid object (a swimming bubble). However, modern high-frequency systems and Fish ID algorithms can assume the size and sometimes type of fish based on signal strength and behavior, but this is only a probabilistic estimate, not a photograph.
Is the sonar bad for fish?
The power of household echoers is negligible and absolutely safe for fish and other aquatic life, and the frequency and power of the pulses have no negative impact on the hearing or health of fish, as confirmed by many ichthyological studies.
What if the sounder shows a “double bottom”?
The double bottom is a secondary echo, and the signal from the bottom bounces off the surface of the water, goes back to the bottom and back again, and it's a sign of a very hard bottom (stone, concrete) and a very sensitive device.Sensitivity) or activate the second echo suppression filter.
How to find fish if it is not at the bottom?
Use the zoom function (Zoom) the middle water layer. Set the upper limit of the range (Top Range) so that it starts 5-10 meters from the surface, if you know that the fish is standing in the waters, it is also useful to use side scanning to look for single objects in the water column.