Fishing from a swimming facility is a game-changer in how we search for fish, turning chaotic wandering around a body of water into a focused exploration of the water. A key tool in this process is a sonar that allows us to look underwater without going down there. A well-chosen device not only shows the depth, but also visualizes the structure of the bottom, the presence of driftwoods, thermocline and fish clusters.
The modern market is saturated with offers from dozens of manufacturers, and it is easy for a beginner to get confused about technical specifications such as the power of the emitter, the scan frequency and the type of display. A mistake in the buying stage can cost not only money, but also lost trophies, as budget models often "blind" at speed or do not see fish in the thickets of grass.
In this article, we will explore all aspects of sonar selection in detail, based on real-world operating conditions on PVC boats and metal boats, you will understand why you need a two-beam sensor and why screen resolution is more important than diagonal on a sunny day.
Principle of operation and main specifications of sonar
The fundamental basis of any sounder is the conversion of electrical impulses into sound waves and back again. The device sends a signal to the bottom, which reflects off obstacles and returns to the sensor. The delay time of the signal determines depth, and the strength of the reflected echo helps classify the object.
One of the most important specifications is work-frequency. Traditionally, 83 kHz and 200 kHz are used. The low frequency (83 kHz) provides a wide viewing angle and greater depth of penetration, which is ideal for finding fish at greater depths. The high frequency (200 kHz) gives a more detailed picture, but with a smaller angle of coverage.
Modern models are often equipped with wide-angle scanning technologies, such as: CHIRP Comppressed High-Intensity Radar Pulse: This technology allows continuous signaling over a wide range of frequencies, which greatly improves target separation and allows you to see fish that would normally merge with the bottom.
The power of the emitter is also critical. For shallow depths of 10-15 meters, 200-300 watts is enough, but if you plan to go to large reservoirs or rivers with strong currents, you will need a power reserve of 500 watts and above for a clear picture on the go.
⚠️ Attention: Do not chase the maximum depth specified in the data sheet. The actual depth of detection of fish is always less than the depth of penetration of the bottom, since the body of the fish reflects the signal worse than solid soil.
When choosing a ceramic element, you should pay attention to the type of emitter: ceramic elements are more sensitive, but fragile when hitting stones, while composite materials are more durable, but may have a slightly less sensitivity to weak signals.
Types of scanning: from classics to 3D
The evolution of sonars has led to several distinct types of imaging of the underwater world: the classic two-dimensional sonar (2D) shows a slice of water directly under the boat. It is a basic tool that no angler can do without, but its capabilities are limited by a narrow band of view.
Side scanning technologies known as Side Imaging or SideScanThey revolutionized search, and they allow you to see the structure of the bottom and fish up to 100 to 150 meters on either side of the boat, and they allow you to quickly survey vast areas, find eyebrows, pits and sunken objects, without going directly over them.
Another advanced method is Down Imaging, which creates a detailed image of the bottom under the boat with a resolution close to the photograph, where the fish is not seen as arcs, but as clear silhouettes, making it easy to distinguish predators from peaceful fish or driftwood.
- 🌊 2D Sonar is a classic mode for determining the depth and presence of fish directly under the keel.
- 📡 Side Imaging is a side scan to search for promising places far from the boat.
- 📸 Down Imaging – Detailed down-scanning to identify the structure of the bottom and the type of fish.
- 🎯 3D Mapping – building a three-dimensional relief map in real time (available in top models).
Combining these modes in one device gives the maximum effect, and the angler can simultaneously monitor the echogram under the boat and scan the coastline from the side, choosing the optimal trajectory.
Selection of emitter: transax or through
The type of sensor installation depends on the design of your boat. For PVC inflatable boats and small aluminum "kazak", the most common solution is a transom mount. The sensor is hung on a transom and immersed in water.
The main advantage of the transom sensor is that it's easy to install and dismantle, and it's easy to remove for storing or transporting a boat on a trailer, but at high speeds, it can pop up due to cavitation, causing interference on the screen.
For plastic or aluminum boats, in-hull sensors are often chosen, and are mounted from the inside of the hull on a special gel, which eliminates algae fouling and impact damage, and are more stable at speeds above 40 km/h.
A separate mention should be made of cast wireless sonars, which are convenient for winter fishing or exploration from shore, but for full-fledged trolling or fishing from a boat, their functionality is often insufficient due to signal delay and short battery life.
⚠️ Attention: When installing a transom sensor on PVC boats, make sure that the fastener does not touch inflatable tubes on a steep wave, otherwise there is a high risk of damaging both the sensor and the boat itself.
Plastic housings are suitable for fresh water, whereas for salt water or aggressive environments it is better to choose metal (bronze or stainless) options to avoid corrosion of contacts.
Display and interface: readability in the sun
The sounder screen is a window into the underwater world, and its quality directly affects the comfort of fishing. The display size varies from 3.5 to 12 inches or more. For a PVC boat, the optimal size is 5-7 inches, since there are few spaces on the cockpit, and a large device will interfere.
A critically important parameter is screen-response On a sunny day, when there's a lot of glare in the water, the dim screen turns into a black mirror. SunMax or similar solutions from different manufacturers provide high brightness and contrast, keeping readable even at noon.
Color rendering also plays a role. Modern color displays use a palette where different colors denote different density of objects. The solid bottom can be shown in orange, and soft silt is blue. Fish are often illuminated in yellow or red depending on the strength of the reflected signal.
The device should be intuitive. The touch screen makes it easier to navigate the menu, but in the rain or with wet hands (which happens all the time on fishing), physical buttons can be more reliable. Many anglers prefer hybrid control.
If you fish with polarization lenses, check the readability of the sounder screen before buying. Some types of matrixes (IPS) can go blind at a certain polarization angle.
Split Screen is a useful feature that allows you to display sonar, navigator maps and side scans at the same time, eliminating the need to constantly switch between modes.
Navigation and cartography
A modern sonar is rarely just a sonar; it's a complete navigation system, and the presence of a built-in GPS receiver allows you not only to mark the points of the fish, but also to build tracks of movement, which is useful for trolling.
Support for memory cards and pre-installed maps are important. Depth maps (bathymetric) allow you to plan a route in advance, bypassing shallow waters. Popular map formats include: Navionics, C-MAP and the manufacturers' own formats.
AutoChart or similar systems allow you to create your own depth maps in real time, and when you walk through an unknown area of the water, you save the relief in the memory of the device, and next time you have a detailed map with the depths.
| Function | Description | Useful for a beginner |
|---|---|---|
| GPS/WAAS | Accurate positioning with signal correction | High (spot search) |
| Waypoints | Preservation of the coordinates of catching places | Critical |
| TrackBack | Return to the track to the fish seen | Medium |
| Compatibility with motor | Control of the traction motor from the screen | Low (for pros) |
Integration with other on-board appliances via network NMEA 2000 It allows you to display sonar data on multifunction displays (MFDs) or even on a smartphone via a Wi-Fi connection, if the model supports this option.
Why do you need WAAS in GPS?
The WAAS (Wide Area Augmentation System) system adjusts satellite signals to reduce the positioning error from 10-15 meters to 3 meters, which is critical when you need to return to a point several meters in size, where yesterday was pestering.
Popular brands and models
The leaders of the sonar market are traditionally considered the “big three”: Garmin, Lowrance and HumminbirdEach company offers unique technologies and an ecosystem of accessories.
Models. Garmin Striker They're famous for their simplicity and robust GPS tracking, and they're perfect for anyone who needs a no-frills "working tool." Echomap It already offers more advanced maps and management.
Brand Lowrance Bets on image detail and scanning technology StructureScanModels of the series Hook are considered "people's" due to the excellent ratio of price and quality, and the series HDS It is aimed at professionals and athletes.
Humminbird He is known for his innovations in 360-degree viewing and technology. Mega ImagingIt's a tool that provides ultra-high-definition images, and for trolling enthusiasts, their devices are often the number one choice.
- 🏆 Garmin is the best GPS and reliability, a simple interface.
- 🎣 Lowrance is the best detailing of the bottom, popular among spinning players.
- ⚓ Humminbird is a cutting-edge scanning and 3D visualization technology.
- 💰 Rivotek / JJ-Connect are budget Chinese counterparts for beginners.
☑️ Criteria for the selection of sonar
When choosing a particular model, you should also consider the availability of service and the availability of spare parts (cables, mounts) in your region, since electronics are a delicate thing.
Practical advice on operation
Buying a sonar is only half the battle; to make it work properly, it must be configured correctly; basic settings include selecting the language, units of measurement (meters/feet) and mode of operation of the emitter (auto/manual).
Sensitivity is a parameter that often requires manual adjustments; in auto mode, the sonar can make noise or lose weak fish. Experienced anglers adjust the sensitivity to make a slight noise appear on the screen, and then slightly reduce it to a clean background.
The speed of the screen scrolling should correspond to the speed of the boat. If you're anchored, you can slow down the speed to see the structure of the bottom in detail. When you move fast, you increase the speed of the scrolling so that the picture does not shrink.
⚠️ Warning: Never turn on a sonar without a submerged sensor (in the air). The emitter can overheat and fail in seconds, as water removes heat and air does not.
Check the status of contacts and wires regularly. Contact oxidation is the most common cause of signal "loss"; use special lubrication for electrical contacts, especially if the boat is stored outside.
The right sensitivity and scroll speed setting is more important than the high price of the device itself. Even a budget sounder with proper tuning will show more than the top-end default.
Compliance with these simple rules will prolong your electronic assistant’s life and ensure stable operation in the harshest conditions.
Can I use a sounder in winter at sub-zero temperatures?
Most modern sonars are designed to operate in a wide temperature range, but lithium-ion batteries lose capacity in the cold very quickly. It is recommended to keep the device warm until the moment you go on the ice and use external thermal cases for power. LCD screens in severe frost can have a reduced response rate (inertia).
Does the echo sounder show a particular kind of fish?
No, the sonar doesn't identify the species with biological accuracy. It shows the size, density of the swim bladder and position in the water column. An experienced angler distinguishes the pike from the pike by the nature of the arc, the depth of the parking lot and the bottom relief, but the program can be wrong to label a large bream as a catfish.
Do I need to calibrate the sounder after purchase?
Factory calibration is usually sufficient to begin with, however, if you use a custom emitter or boat with a special bottom coating, you may need to adjust the speed of sound in water (depending on salinity and temperature) to accurately map the depth. In fresh water, the standard sound speed is about 1,440 m/s.
Does the boat's movement affect the sonar readings?
Yes, at high speeds (above 30-40 km/h), air bubbles (cavitation) form under the sensor, which shield the signal. Speed boats require special high-speed sensors with a streamlined shape or the installation of the sensor in the hull (through mount) in a place free from bubbles.