Operation of a watercraft made of metal imposes special requirements for the installation of navigation equipment, differing from standard procedures for fiberglass or PVC. aluminum It is an excellent conductor of electricity, which poses a risk of electromagnetic interference that distorts sonar readings, and owners of such vessels often encounter "noise" on the screen, which completely hides the bottom relief and fish.
Literate sonar It requires careful body preparation, the right location for the sensor and the right screening of the wiring. Errors during the installation phase can lead not only to loss of signal, but also to damage to the device itself due to wandering currents. In this article, we will discuss all the technical details that will help you get the perfect picture even at high speed.
Before drilling holes, you need to clearly understand the physical nature of the propagation of ultrasound in water and its interaction with the metal bottom. garmin, Lawrence. or hamming No matter the brand, the way we work is the same, and if you install a transducer incorrectly, you'll lose even the most expensive equipment.
Selection of place and preparation of transom
The first step is to find the optimal zone to place the emitter. The surface of the metal should be flat, without strong bends, ribs or rivets in the immediate vicinity of the scanning center. transom plate often has a complex geometry, so it is better to fit on the switched-off device, temporarily fixing the sensor with tape or a sucker.
It is important to consider the angle of attack and the flow of water. When a boat moves, the water must flow around the sensor smoothly, without the swirls and air bubbles that are the main enemies of echolocation. Aluminum flat-bottomed boats often have a cavitation effect at high speeds if the sensor is installed too high or at the wrong angle.
⚠️ Warning: Never place the sensor near the motor brackets or elements that create severe turbulence. Air bubbles stick to the working surface, completely block the ultrasonic signal.
For mounting often use special brackets that allow you to adjust the height and angle of inclination. If you plan to use a boat in shallow water, consider the option of a folding bracket that will rise when hitting an obstacle, maintaining the integrity of the knot.
Features of the sensor insertion into the metal body
One of the most aesthetically pleasing and efficient ways is to insert the sensor directly into the bottom, which eliminates water resistance and the risk of damage when mooring, but requires high precision. Aluminum alloy It is easy to process, but the thickness of the metal must be taken into account when choosing a sonar model - not all devices are able to penetrate a double layer of metal.
The process starts with marking. Use the template that comes with the kit, or make it yourself out of cardboard. The center of the hole should match the center of the active surface of the emitter. It is better to drill through metal with a gradual increase in diameter to avoid biting and deformation of the sheet.
Do I need water contact with the sensor when inserted?
In-hull, the water must not contact the sensor directly, and the space between the hull and the bottom of the boat is filled with a special silicone sealant or oil that is acoustically transparent, which protects the electronics from corrosion and fouling, while maintaining the quality of the signal.
Once the hole is ready, you need to degrease the surface, and you put the sensor on a layer of sealant that fills all the micro-nerves, and you need to squeeze all the air out of the sole, because the airbag will be an insurmountable barrier to ultrasound.
☑️ Checklist for cut-in installation
Protection against electromagnetic interference
The metal hull of the boat works like a huge antenna, collecting tips from the engine, ignition system and other electronic devices. electromagnetic interferenceThe wiring needs to be done in shielded corrugated tubes, and the plastic is not going to help, it's metallized protection.
Special attention should be paid to grounding. All electronic components should have a common grounding point connected to the battery's negative terminal. Other potentials on the boat hull and the appliance can create background noise that looks like chaotic stripes on the screen.
| source of interference | Screen-on-screen symptom | Elimination method |
|---|---|---|
| Ignition system | Frequent vertical stripes | Wire shielding, installation of ferrite rings |
| Radio station | Horizontal bands in transmission | Increased distance between antenna and sounder |
| Poor grounding | Constant background, noise | Organization of a common earth tyre |
| Electric motor | Rifts in engine operation | Separate batteries for sonar or filters |
Use high-quality waterproof connectors. The oxidation of the contacts in an aluminum boat is faster due to electrochemical corrosion. The use of copper tips and terminals without coating can start the reaction of the galvanic pair with an aluminum body, so tinted copper or stainless steel is preferable.
Installation of the display and organization of space
The headset is not just a matter of convenience, but also of safety. The screen must be clearly visible to the steering wheel, but not overshadowing the view. Aluminum boats often use cushioned swivel brackets, as the metal transmits vibration rigidly to the mounting screws.
Wire inside the cockpit should be hidden in cable channels or under removable floorboards. Open-lying wires can be damaged by gear, anchor or just hit by the foot. Use special sealants to pass wires through the board, which tightly compress the cable and prevent water from entering.
Use Velcro cable screeds to temporarily fix wires during testing so as not to drill extra holes in the sides until the system is debugged.
Make sure that the display is freely accessible to remove the memory card or adjust the menu. Often, once the tap is installed, you can't get to the connectors without dismantling the entire structure.
Connection to the on-board network and battery
Modern sonars are sensitive to voltage surges, and connecting the device directly to the battery through a standard wire is the right solution. Using a lighter in an aluminum boat often leads to poor contact and a voltage drop under load.
Be sure to install the fuse in the break of the plus wire as close as possible to the battery terminal. The fuse value must meet the manufacturer's requirements (usually 3-5 Ampere) This will protect the wiring from fire in the event of a short circuit, which in a metal boat is especially dangerous.
⚠️ Warning: Do not connect the sonar to the same battery used to start a powerful starter motor without additional protection. The start currents can cause voltage drawdown and reboot or damage to the electronics.
To check the quality of the connection, use a multimeter. The voltage at the input of the device with the engine running should not exceed 14.5-15 Volts, and when starting the engine - fall below 10 Volts.
System setup and calibration
After physical installation, there is a software setup stage, where you have to choose the type of sensor you have installed and the frequency of the radiation from the menu, and aluminum boats with cut-in sensors sometimes need to manually set the speed of sound, although modern models do this automatically.
Set up sensitivity (sensitization).Sensitivity) and noise cancellation (Noise RejectionStart with automatic mode, then gradually reduce the sensitivity until the excess noise disappears, but the bottom relief is still clearly visible. Excessive noise cancellation can eat small fish.
The right sensitivity setting is more important than the power of the emitter, and a well-calibrated budget sonar will show more than a powerful but chaotic device.
Check the different speeds, and if there's any interference on the move, it might be that the sensor picks up the air bubbles, and you'll need to re-adjust the angle of inclination or lower the sensor below the bottom.
Frequently Asked Questions (FAQ)
Can I attach the sounder sensor to the tape inside an aluminum boat?
Technically, it's possible for temporary use or testing, but it's not recommended for permanent use. Bilateral tape loses its properties over time from vibration and temperature changes, and the air between the tape and the metal will degrade the signal. Better to use a sealant or a special bracket.
Why does the sounder show a “double bottom”?
The double bottom effect often occurs when the automatic_gain_control is too sensitive or not working properly, and it can also be a sign of a thermocline in water, try to reduce sensitivity or switch the sonar mode.
Do I need to lubricate the thread when installing the sensor?
Yes, be sure to use marine lubricant or corrosion-resistant compounds on threaded joints. Aluminum and stainless steel (which bolts are made of) in salt or even fresh water form a galvanic pair, which can cause the fastener to "fix" through the season.
Does the thickness of the aluminum bottom affect the sounder?
Yes, it does. Most household sonars are able to penetrate aluminum up to 10-12 mm thick. If the bottom of your boat is thicker (for example, reinforced by profiles), the signal may be too weak or absent.