Introduction to underwater echolocation
Boat fishing is very different from shore fishing, providing access to deep pits and distant eyebrows where the trophy fish hides. But without special equipment, the angler remains blind, relying only on luck and bottom relief, guessed by the bursts. sounder A device that can turn the water column from a dark mystery into a transparent map with designated goals.
Modern devices display not only the depth, but also the structure of the bottom soil, the presence of vegetation and, most importantly, the silhouettes of fish of different sizes. A key advantage of the boat sonar is the ability to scan on the go, which allows you to quickly explore large areas in search of clusters of fish. Understanding the principles of this gadget will be the foundation for your successful trips to the water.
Principle of operation and main specifications
So, any sonar is based on a simple physical principle: the emitter sends a sound pulse into the water, which reflects off the obstacles and returns back, and the time of the signal travels allows you to calculate the distance to the object, and the strength of the reflected echo to determine its density. Radiation frequency It is a critical parameter that affects the detail of the picture and the depth of penetration.
High frequencies (e.g., 200 kHz) give a more detailed picture, but they fade faster in water, so they are suitable for shallow water. Low frequencies (50 kHz) penetrate deeper, but the image becomes more blurry. Many modern models, such as the one that is used in the water, are more sensitive to the light. Garmin Striker or Lowrance HookThey use dual-frequency sensors, allowing them to switch between modes or use them simultaneously.
What is CHIRP and why is it needed?
CHIRP (Compressed High-Intensity Radar Pulse) technology allows the sonar to send not one frequency pulse, but a whole spectrum of frequencies. This greatly increases the resolution of the picture and allows you to distinguish between individual targets located next to each other, which is especially important when catching schooling fish or in overgrown bodies of water.
And don't forget the power of the transmitter, which is measured in watts (RMS), and the higher the power, the better the device can "pierce" thermocline and show details at great depths, but for most freshwater bodies, excess power is not required, and here the quality of the signal processing by the device's processor is more important.
- 🎣 Frequency: It determines the detail and depth of the scan.
- ⚡ Power: It affects the ability to penetrate water columns and thermoclines.
- 📐 Viewing angle: The width of the scanning cone (usually 15 to 60 degrees).
- 🖥️ Screen resolution: The number of pixels that affects the clarity of the image.
Types of sonar for boats
The type of device you choose depends on your type of boat and fishing style. Fishers using inflatable PVC boats often prefer compact portable models, they are lightweight, run on an integrated battery and easily attached to the board with special suction cups or hairpins.
For metal or plastic boats with a fixed installation, hull sonars with the possibility of mounting the sensor through the hull (through the side) or per transom are better suited. Humminbird HelixThey have more power and screens with a high diagonal, which is convenient in bright sun.
Separately, we'll highlight the cartplotter sonar sonar sonar sonar sonar sonar sonar sonar sonar sonar sonar sonar sonar sonar sonar, which allows you to not only see fish, but also put dots on a map, return to catchy places and plot routes, and is the most versatile solution for a serious angler.
Water protection is also important to consider when choosing. If IPX7 is the standard for stationary models, then IPX8 or at least a confident IPX7 is desirable for portable devices that may accidentally fall into the water.
Criteria of choice: what to pay attention to
Buying a first or a new sonar can be confusing because of the abundance of features. The first thing you do is decide on your budget, but remember that in this area, the price is often directly proportional to the quality of the picture and the response speed. Cheap models can "lose" the bottom on speed or excitement.
The second important aspect is the size and type of screen. For a boat, readability in bright sunlight is critical. Matt screens here beat glossy screens that shine. A diagonal less than 4-5 inches can be inconvenient for looking at the structure of the bottom in detail, although for simple tasks, depth/fish is quite sufficient.
When buying a sonar, be sure to check the equipment for mounts. Often the basic versions are without a transom mount, and it has to be purchased separately, which increases the total cost.
Also worth paying attention to the interface and menu, the controls need to be intuitive, so that you can adjust directly on the water, without distracting from the control of the boat, and the presence of a Russified menu for many is a prerequisite for comfortable operation.
- 🔋 Autonomy: One-charge operation time (for portable models).
- 💧 Moisture protection: IP class, which guarantees survival in case of water.
- 🔌 Interfaces: NMEA 2000 is available for integration with other devices on board.
- 🗺️ Cartography: Support for detailed maps of the fishing region.
Comparative table of popular models
To organize the information, consider some popular models that have proven themselves in the market, and the data in the table will help to form a primary idea of the capabilities of different devices in similar price categories.
| Model | Screen type | Frequency (kHz) | Features |
|---|---|---|---|
| Garmin Striker 4 | 3.8" Colored | 77/200/455 | Built-in GPS, simple interface |
| Lowrance Hook2-5 | 5" Sunny. | 83/200/455 | Autotuning, wide viewing angle |
| Humminbird Helix 5 | 5" Colored. | Two-beamed | Down Imaging Technology, Detailing |
| Practik 7 Pro | Monochrome | 100 (adaptive) | Russian software, work in the cold, simplicity |
As you can see from the table, even budget models today are equipped with color displays and GPS modules, the choice between them often comes down to menu preferences and map availability for a particular region. Solar Or similar will be much more comfortable to use during the day.
Don't chase the maximum number of functions. For 90% of tasks, an amateur fisherman needs a reliable two-frequency sonar with a GPS and a 5-inch screen.
Installation and configuration of the sensor
The right sensor is 80 percent of the time you get a good picture. The rule for transom models is that you have to be submerged in water and in a calm flow, without any bubbles, and the airbag completely blocks the signal.
You need to attach the sensor to a strictly horizontal or minimal angle of inclination, so that the beam looks vertically down. If the boat glides, the sensor should be lowered below the bottom level so that it does not capture air when moving. Inflatable boats ideal floating sensors on the fishing line or mounting on suction cups on board.
☑️ Verification of sensor installation
⚠️ Attention: Never cut the sensor cable unnecessarily! Shortening the cable breaks the matching (impedance) and can lead to loss of warranty and signal degradation. If the cable is too long, it's better to fold it neatly into a bay, but not into a small diameter ring.
Sensitivity and depth range (Range) also play a role. In automatic mode, sonars work well, but for finding small fish or studying the bottom in detail, you better go manually. Adjust the sensitivity so that there is light noise on the screen, and then reduce it a little bit to the disappearance of noise, this will give maximum detail.
Echogram reading and frequent errors
Learning to read an echogram is learning to see fish. The fish is shown as arcs. If the boat is standing, the arcs turn into vertical stripes. The hard bottom is shown as a bold red or orange line, and the soft silt is thinner and more intermittent. It's important to distinguish between fish and bottom inhomogeneities.
One of the common mistakes of beginners is to set too high sensitivity, which fills the entire screen with "porridge" of interference. The other extreme is the low speed of updating the screen (Speed of Scroll), which causes the picture to stretch and become unreadable in the parking lot.
Why does the sonar show two arcs?
Sometimes you see a double echo from the bottom, and this happens when the signal bounces off the bottom, then off the surface of the water, and then goes back to the bottom, coming back, and this is normal for deep places with a solid bottom, and it's good for the device.
Fishers also often confuse driftwood and vegetation with fish, with vegetation usually having a tail that goes down from the bottom, and driftwoods looking like chaotic clouds, and fish have clear contours and are usually not "plaque" at the bottom (except for bottom species), but are in the water column.
- 🐟 Dougie: A classic image of a fish in motion.
- 🌿 Vegetation: green or yellow stripes that extend down from the bottom.
- 🪨 Rocks/Snags: dense spots of red or orange color.
- 🌡️ Thermoclin: horizontal interference band separating the water layers.
Maintenance and care of the device
The aquatic environment is aggressive, especially when it comes to salt water or bodies of water with blooming water. After each fishing, the device and the sensor must be rinsed with fresh water. Salt and dirt, drying, can damage the seals or the shielding braid of the cable.
Store the sonar in a dry place, preferably in a case or box. The battery (if it is removable) is better to keep charged by about 60-70% if the device is not used for a long time, this will prolong the battery life.
⚠️ Attention: Do not expose the sonar screen to direct sunlight when turned off for a long time (for example, leaving a boat on the torpedo). This can cause the matrix to burn out and spots that do not disappear.
Check the status of contacts and connectors regularly. Contact oxidation is a common cause of signal loss or unstable operation. Using silicone lubricant for connectors will help avoid oxidation problems in the future. Careful treatment of the device will ensure its long and reliable service for many seasons.
Can a sea sonar be used in fresh water?
Sea sonars often have a more powerful emitter and a more protected housing, which in fresh water will be only a plus, the only caveat is that the sensitivity settings may differ, because salt water conducts sound better, but modern instruments automatically adapt or have presets for different types of water.
Does the speed of the boat affect the sonar readings?
At high speeds (planing), the sensor can capture air bubbles (cavitation), which causes the signal to be lost, and at high speed, the echogram is very stretched, and for detailed examination of the bottom, it is better to slow down or stop.
Why can't the sonar see fish under the ice?
Conventional transom sensors do not work through the ice, since there is no contact between the sensor and the water (the air layer cancels the signal); for winter fishing, special winter sensors are needed that are placed directly into the hole, or sonars with the function of working through the ice (although the latter are rare and work inefficiently).
Should I calibrate the sonar?
Factory calibration is usually sufficient, however, if you notice a systematic error in depth (for example, the sonar shows 5 meters, and on the tested lot 5.2), you can make an adjustment in the settings of the sound speed or offset of the sensor (Offset), especially if the sensor is installed outside the standard.