Buying the first sonar for a motorboat is always a balance between wanting to get the most information and having to keep a budget. Unlike shore fishing, where depth is all that matters, on water with a motor, the speed of screen refresh and clarity on the move becomes critical. Many beginners make the mistake of buying simple models that smear the picture at 10 km / h, turning the bottom into porridge from pixels.
The modern market offers a huge variety of solutions: from budget single-beam The choice depends on the type of reservoir where you plan to fish and the tasks you face. If trolling at great depths is important for detailing the structure of the bottom, then for sea fishing in shallow waters, the response rate and the angle of view are critical.
In this article, we will discuss all the technical nuances that will help you make an informed decision. radiation Power is more important in some situations, and how to choose the right sensor for your type of boat.
Key specifications: power and frequency
The first thing a shopper looks at in a store is the power of the transmitter, but for a boat with an engine, especially if you're fishing not only in the depths but also in the shallows, it's more important to understand the physics of working. ultrasoundPower is measured in watts (RMS) and affects the ability of the device to penetrate the water column and show the bottom at depths of more than 30-40 meters. For most inland water bodies in Russia, a power of 200-300 watts is quite enough.
A much more important parameter is the frequency of radiation. Standard sonars operate at 50 kHz and 200 kHz. Low frequency (50 kHz) has a wide cone and greater penetrating power, but gives a less detailed picture. High frequency (200 kHz) provides detail but has a narrow cone of view. Modern models often use technology. Dual Frequency or CHIRPThey combine the advantages of different frequencies.
⚠️ Warning: Using a sonar at maximum power in shallow water (less than 2 meters) can result in a “second bottom” on the screen and false depth readings due to overreflection of the signal.
Technology CHIRP The Comppressed High Intensity Radar Pulse has become the standard for fishing sonars, which emits not just a single fixed frequency signal, but a whole packet of frequencies over a specific range, and it allows for much better target separation and image clarity, which is especially important when looking for fish in dense jambs or at the bottom.
When choosing a sonar, pay attention not only to the declared power, but also to the type of emitter. Ceramic elements in CHIRP sensors are usually more efficient than older piezoelements.
Types of scanning: classics against new technologies
Traditional 2D scanning shows a vertical slice of water just under the boat, enough to navigate and find the differences in depth, but for detailed terrain and search for single fish, this is not enough. DownScan, SideScan or StructureScan.
Side scanning allows you to see what's happening on the sides of the boat up to 100-150 meters in each direction. This turns the sonar into an exploration tool, allowing you to find eyebrows, bins and fish parks without swimming over them directly. The bottom scan gives a photographically clear image of the bottom under the boat, where you can see individual rocks, branches and even a species of fish.
- 🎣 Classic 2D: Ideal for determining depth and finding fish in the water column when moving.
- 🗺️ Side scan: You need to search for specific fishing points and study the structure of the bottom over a large area.
- 📸 Lower scan: It allows you to distinguish the type of bottom vegetation and accurately identify the object at the bottom.
It's worth noting that high-resolution modes require a more stable position of the sensor, and if you have a strong chatter or a high speed boat, the picture can be distorted, so for aggressive driving on the motor, it's better to be able to switch to the classic mode with a wider diagram.
Sensor and its installation on a boat with an engine
Choosing the right sensor (emitter) is 80 percent of the success of the entire system. For motor boats, the two most popular types of attachment are the transom and the treadmill (through the hull). Transom sensors are versatile, easy to install and remove, but create resistance to water and can be damaged when hitting an obstacle or when pulling a boat ashore.
Cutting sensors are placed in the bottom of the boat (PVC or metal) and do not create resistance. They give a cleaner signal at high speeds, because there are no air bubbles between the sensor and the water. However, their installation requires accuracy and tightness, and replacement in case of breakage is much more difficult. For aluminum boats, there are also sensors that are attached through special holes in the bottom.
⚠️ Warning: When installing the transom sensor, make sure it does not fall into the turbulence zone from the motor screw or gearbox. Air bubbles running into the sensor completely block the sounder signal.
A wide beam (like 60 degrees) is good for shallow water and fish search, but it is less accurate in determining the structure of the bottom. A narrow beam (10-20 degrees) gives an accurate picture under the boat, but requires perfect positioning. Many modern sensors have a variable angle of view.
☑️ Check before installing the sensor
Screen and readability in the sun
When you're on a boat, often in the bright sun, screen quality becomes critical. Budget models with TN arrays can go completely blind at a certain viewing angle, making fishing impossible. A comfortable work requires a screen with an IPS matrix or high-quality illumination that provides wide viewing angles.
On small screens (3-4 inches), high resolution (e.g. 480x800) allows you to see small details that will merge into a single spot on a 240x320 screen, but it’s worth remembering that high resolution requires a more powerful processor to render the picture quickly.
Size the diagonal based on the size of the boat and the distance to the operator's eyes. For inflatable boats and compact "chank" screens 5-7 inches are optimal. Large screens (9-12 inches) are convenient for splitting into two parts (Split Screen), when simultaneously displaying the map of the navigator and the sonar image.
- ☀️ Brightness: A minimum of 800-1000 nits for comfortable work during the day.
- 👀 Viewing angles: IPS-matrixes are preferred over TN.
- 🖐️ Management: Touch screens are comfortable, but buttons are more reliable in gloves and when shaking.
Comparison of popular models and brands
The market is dominated by several major players, each offering their own unique technologies. Garmin It has excellent maps and ecosystems, Lowrance and Simrad are considered the world's benchmark for sounders with advanced scanning, and Humminbird offers excellent solutions for price/quality ratio. Chinese brands, such as Erchang or Deeper (for winter fishing), occupy a niche budget devices.
When choosing a particular model, it's important to look not only at hardware, but also at software. Signal processing algorithms vary from manufacturer to manufacturer. Where one sonar shows just an "arch," another can draw a detailed swim bladder of a fish. Software support and firmware updates also play a role in the longevity of the device.
| Brand | Key technology | Price segment | Feature |
|---|---|---|---|
| Garmin | ClearVü / SideVü | Medium/High | Best navigation and maps |
| Lowrance | DownScan / StructureScan | Medium/High | Detailing the structure of the bottom |
| Humminbird | Down Imaging / Side Imaging | Budget/Average | Availability and reliability |
| Raymarine | DownVision / SideVision | Highly | Professional Marine Series |
Why are branded sonars more expensive?
The difference in price is not just due to the logo: Leading brands are investing millions in R&D departments, developing their own CHIRP signal processing algorithms and improving noise immunity. Cheap counterparts often use ready-made Chinese modules that are worse at filtering noise from the motor and sonar of neighbors.
Nutrition and energy consumption
A motor boat is usually battery-powered, but connecting a sonar requires attention to detail. Most appliances run from 12 volts, but power surges when running a motor starter or charging from a generator can be fatal for electronics.
Current consumption with a modern sonar is small (usually 0.2-0.5 Amps), but if you plan long autonomous fishing with GPS on and backlighting, this is worth considering. For lithium-iron-phosphate (LiFePO4) batteries, discharge up to 20% is not terrible, whereas for lead-acid deep discharge can reduce the life of the battery.
When installing, use separate fuses installed as close to the battery as possible. Wiring should be laid away from motor power cables and radio interference sources to avoid tips on the screen.
Proper organization of power supply and protection from voltage surges prolong the life of the sonar longer than careful handling of the device itself.
Frequently Asked Questions (FAQ)
Can I use a sonar in winter to take it off a boat?
Yes, many models allow this. However, you need to consider the temperature range of the battery and the screen. Lithium batteries lose charge quickly in the cold, and LCD screens can "wash" or react slowly. For winter fishing, it is better to use specialized winter sonars or models with a wide temperature range.
Can you see the fish on the echoer or just the bottom?
Modern sonars see fish very well. The fish is displayed as characteristic arcs (if it swims through the cone of the beam) or static spots. The size and shape of the "arch" depends on the size of the fish and its position relative to the sensor. CHIRP technology allows you to see even small fish and distinguish between schools.
Do you need a GPS module in the boat sonar?
For a motorized boat, a GPS module is highly desirable, so you can save the coordinates of the catch points, build tracks of the path and, most importantly, use the anchor function on the screen to understand where you've been and where you haven't gone before. Without a map and GPS, the efficiency of finding fish is reduced.
How often do I need to update the sounder cards?
The bottom terrain changes slowly, so frequent updates to the topography maps are not required. However, maps of navigation signs, depths and markers can be updated by manufacturers once a year or less. For most fishing tasks, the basic maps included in the package are enough for many years.
Why does the sonar show "porridge" at speed?
This can be due to several reasons: improper installation of the sensor (infection with bubbles), too high sensitivity (gain), or a slow refresh rate of the screen of the device itself. Try to reduce the sensitivity and check the angle of inclination of the sensor.