The right attachment of the sonar sensor to the boat is the foundation for obtaining a high-quality and reliable picture of the underwater world. Many anglers, buying expensive electronics, mistakenly believe that it is enough to simply attach the transducer to the transom to get the perfect picture. However, errors in the initial installation cause the "noisy" screen, loss of signal at speed or inability to distinguish the structure of the bottom.
The quality of the image on the display directly depends on how competently the installation point is chosen and the technology of work is observed. Hydrodynamics The flow of water around the working surface of the sensor plays a crucial role in the stability of the sonar. In this article, we will discuss in detail the nuances of installation on various types of boats, methods of combating cavitation and secrets that will allow your sonar to work with maximum efficiency.
Before picking up a drill or tube with a sealant, you need to carefully plan the entire installation process. Lowrance, Garmin, Humminbird Regardless of the brand, the physical laws of sound wave propagation are the same for everyone. The optimal depth of the working surface of the sensor is 3-5 mm from the keel line or the lower plane of the transom.This minimizes resistance and ensures a clean signal.
Choosing the optimal location for installing a transducer
Finding the perfect place to fit is a process that requires patience and understanding how the water behaves under a moving boat. The main task is to find a site where the water flow is laminar, that is, smooth and without swirls. The air bubbles that fall under the working surface of the sensor create a "shielding" effect, which causes the device to stop seeing the bottom or begins to draw false arcs.
When choosing a place on the transom, you need to consider the design of the outboard motor and its lower unit. Often the sensor is installed to the left of the motor leg, because this is the side on which the forward movement creates a zone of relatively calm water. However, some boats with complex bottom geometry can twist the flow in this area, so experimental testing "on the water" is required.
It is also important to consider the angle of inclination of the transom. If it is heavily backed up, the standard anchorage may not provide perpendicular input of the beam into the water, which will distort the depth readings. In such cases, it may be necessary to manufacture an additional bracket or use adjustable holders.
- 🌊 Look for a place where the surface of the water when the boat moves remains smoothest and does not foam.
- ⚓ Make sure that there are no protruding elements, rivets or irregularities at the selected point that create turbulence.
- 🔌 Check if the sensor cable will reach the head unit installation site without tension and risk of damage.
⚠️ Warning: Never install the sensor directly in front of the engine's lower unit or in the path of exhaust gases. The exhaust stream is saturated with air and completely blocks the sounder, turning the screen into a chaotic flash of noise.
Installation of PVC boats and composite
Installation on soft or composite transverses requires a special approach to fixation, since drilling holes in such materials is not always desirable or possible. For PVC boats, the most common method is the use of special pressing brackets that are attached to the top of the transom using bolts or powerful rods.
When mounting on a composite or plywood transom with an outer skin, it is important to correctly calculate the entry point of the cable. If you decide to run the cable through the hole in the transom, the edges of the hole must be carefully treated and protected from moisture.cable glands) will greatly simplify the task and provide a reliable insulation.
For temporary installation or fishing in shallow water, many use suction cups or magnetic fasteners (for steel boats), but they are less reliable at high speeds. Permanent fastening should withstand shocks to water when turbulent and not deform under load.
An important aspect is the protection of the cable itself at the exit point of the sensor body. Excessive bending or rubbing against the hard edge of the transom can cause electronics to fail. It is recommended to use a corrugated tube or rubber Cambricks to organize a smooth bend radius.
Features of installation on metal and plastic boats
Metal and plastic boat owners often face the challenge of placing a sensor inside the hull to avoid fouling and mechanical damage, a technique known as in-hull that requires careful seating and the use of special freeze-free liquids or epoxy compounds to transmit the signal.
When installing a "through the side" on a metal case, it is critical to use insulating sleeves to prevent electrochemical corrosion between heterogeneous metals (for example, a bronze sensor and an aluminum case). Contact of two different metals in salt water will lead to the rapid destruction of the less noble metal.
For plastic cases, especially multi-layered ones with filler (sandwich), you need to make sure that there are no voids or wooden inserts in the installation site that can absorb ultrasound, sometimes you have to cut out part of the skin and paste a special fairing.
| Type of installation | Advantages | Deficiencies | Complexity |
|---|---|---|---|
| transom (outside) | Ease of installation and adjustment | Risk of damage, fouling | Low. |
| Through the hull | No resistance, protection | Complex installation, risk of leakage | High. |
| In-hull. | No drilling, sensor protection. | Loss of signal power, body requirements | Medium |
⚠️ Note: When drilling holes in the metal case, be sure to use a centrifugal drill and coolant. Overheating the metal can damage the paint coating and change the structure of the alloy around the hole.
Sealing of compounds and protection against moisture
Water is the enemy of all electronics, and the quality of the sealing determines the durability of your sonar system. Even if the cable is labeled "waterproof," the connections to the head connector or the sensor itself are vulnerable points. Using quality materials here saves money for repairs in the future.
Specialized polyurethane-based marine sealants, such as those for sealing threaded connections and cable entry points, are best suited. 3M 4200 or BoatLife Life CaulkThey retain elasticity after drying, which allows you to compensate for the vibration of the boat hull without cracking, unlike them, silicone sealant can eventually peel off under constant exposure to water and ultraviolet.
When connecting wires, if you want to build up or repair, you need to use soldering, followed by insulation with thermal shrink tubes with adhesive layer. Conventional insulation in the sea air and under the influence of salt water will quickly become unusable, oxidizing the contacts.
☑️ Pressurization check
Pay special attention to the connector that connects to the head unit, often that is where moisture gets due to condensation or splashing, it is recommended to additionally wrap the connection site with a self-amorizing tape, which, when stretched, is fused into a monolithic rubber layer.
Fighting cavitation and speed interference
Cavitation is the process of vaporizing and popping bubbles in a fluid stream that occurs when pressure changes dramatically. For a sonar, cavitation means a cloud of bubbles in front of the sensor that completely reflect the signal. On the screen, it looks like white vertical stripes or the bottom disappears completely when you dial speed.
Often the cavitation is caused not by the sensor itself, but by foreign objects next to it: sticking bolt heads, uneven transoms or even algae winding on the mount. Careful surface preparation and installation of fairings in front of the sensor help to break the flow and direct it in a smooth stream.
If you only have a problem at high revs, try lowering the sensor down, sometimes 5-10 mm is enough to get out of the turbulent layer adjacent to the bottom, and it's also worth checking the angle of inclination: if the sensor nose is too high up, it starts to row the air.
Secret methods of combating cavitation
Some anglers use antifowling sprays that not only prevent fouling, but also create a slippery hydrophobic film that improves streamlining, and also help to install a small visor in front of a sensor that breaks the oncoming flow of water.
It's important to distinguish between cavitation and electrical interference. If the noise on the screen appears even in the parking lot with the engine running, perhaps the sonar cable is too close to the motor power wires or the GPS antenna. The cable's shielding and the right wiring of the current-carrying parts will solve this problem.
Customization and calibration after installation
After physical installation and leakproofing, there is a software adjustment phase, and even a perfectly installed sensor requires that the sounder menu be adjusted to display accurate data, and the first step is always to set the type of transducer installed unless the system automatically detects it.
The speed of sound in the water varies depending on temperature and salinity. For freshwater bodies, the standard settings are usually suitable, but when going out to sea fishing, you need to make adjustments to the water. Settings → Sonar → Speed of SoundIgnoring this parameter will lead to errors in the readings of depths up to 10%.
It is also necessary to adjust the sensitivity (Sensitivity) and noise reduction (Noise FilterExcessive sensitivity will show a lot of “junk” in the water column, and too aggressive noise cancellation can hide small fish. The optimal mode for searching is automatic, but with manual adjustment to specific conditions.
Save your settings as a user profile (e.g., River, Lake, Sea) and allow you to switch between modes quickly when changing locations without reconfiguring the sonar every time.
Remember to check the sonar at different speeds. Walk through the water body idling, then add the gas and see how the image behaves. If the signal breaks at speed, go back to adjusting the depth of the sensor.
The sounder's image quality is 80 percent dependent on the sensor being installed correctly, and only 20 percent on the device's capabilities. Don't neglect the installation time.
Can I attach the sounder sensor to a plastic clamping or scotch?
Plastic clamps or tape are allowed only as a temporary solution for testing the installation site. For permanent use, such methods are not suitable: plastic is destroyed by ultraviolet light, and the tape glue loses its properties in water. Reliable fastening requires a metal or composite bracket on bolts with counternuts.
Why does the sonar show the arcs of fish only when the boat is moving?
For the classical Archimedes arc to form, you have to change the angle of input of the signal into the fish, and when the boat is standing, the beam passes through the fish at one angle, drawing a stripe, and the movement changes the angle of scanning, which creates a characteristic arc, which is a normal physical phenomenon, not a malfunction.
How often should I change the anode on the sensor?
A zinc or magnesium anode that protects the sensor from galvanic corrosion requires regular inspection, should be checked after each exit in salt water, and replaced with a loss of 50% of the mass. In fresh water, the anode resource is much higher, but monitoring is also necessary once a season.