Operation of inflatable watercraft directly depends on how competently executed thruster-mountingMany beginners make the mistake of thinking that it is easy to fasten a lower unit to a board, but it is precisely positioning accuracy that determines not only speed performance, but also safety on the water. The wrong angle or height can lead to the boat's "goat", cavitation of the screw and even the breakage of the lower unit when hitting a wave.
In this article, we will take a detailed look at all the stages of installation, from the preparation of the workplace to the final adjustment of the angle of the trim, and learn how to avoid common errors that often lead to loss of traction or damage to the transom of the inflatable boat. outboard This is the key to fuel economy and comfort during long walks.
Consider that modern inflatable boats have design features that distinguish them from rigid hulls. The flexibility of the transom requires a special approach to tightening bolts and using gaskets. Security In this context, it comes to the fore, because the engine tearing off on the move is a critical situation that requires an immediate response.
Preparation of the transom and selection of the installation site
Before you start installing, you need to make sure that the transom of the boat is fully loaded. The surface should be clean, dry and free of foreign objects. If the transom already has rod holders or sonar holders, make sure that they do not interfere with the work of the lower unit or the creation of a jet of water. It is critically important to check the condition of the overlay on the transom: the presence of cracks or plywood layers is unacceptable when installing a powerful motor.
Determine the center of the transom, as the motor must be positioned strictly on the diametrical plane of the boat. Sideways will cause the vessel to constantly yaw and have to constantly adjust its course, which tires the operator. Use the tape measure the distances from the sides to the center of the mount to ensure symmetry.
For boats with a hard transmessel (whether pasted or removable), it is important to check the reliability of the board's mountings to the cylinders. On soft transmessels (inflatable), installation is only possible for low-power models, and there is an additional rigid plate required to distribute the load. fitting-ground It should be flat.
Don't forget to prepare all the tools you need in advance. You'll need a proper size wrench, screwdrivers, and possibly a dynamometer key to control the tightening force, and you'll also need a threaded lubricant to protect you from corrosion in salt water.
Adjustment of the height of the suspension of lower unit
The height of the engine is a parameter that is most often ignored, although it directly affects the efficiency of the propeller. If the motor is installed too low, water resistance increases, leading to a drop in speed and fuel consumption. Too high a landing causes a screw air sucker (cavitation), which manifests itself in a sharp increase in engine speed without increasing speed.
The optimal position is considered to be one in which the anti-cavitation plate (horizontal plate above the propeller) is at the same level with the bottom of the boat or 10-25 mm below it, depending on the type of hull. Inflatable boats with a flat bottom often require lowering the engine slightly lower than for boats with pronounced keeled contours.
- 🛠️ Check that the screw when moving does not capture air bubbles from under the bottom.
- 🌊 Make sure that the lower unit is submerged deep enough to cool the engine efficiently.
- ⚙️ When installed on boats with high transes, a lower unit extension may be required.
The height adjustment process is carried out by moving the motor through vertical holes on the transom board or using special adjustable brackets. After each change in position, a test swim must be performed. Testing It is better to carry out with a full load of the boat, since on a light vessel the engine can stand high, and when landing passengers - go down too deep.
Adjustment of the angle of inclination (different)
The angle of the motor relative to the transom, or the different, is key to achieving glides. The right angle allows the bow of the boat to rise, reducing the contact area and resistance. Adjustment is done by a thrust bolt (pin) in the motor's mounting mechanism, which locks lower unit in one of several positions.
If the boat's nose gets too upward when it goes into planing, it becomes unstable and prone to yaw, and then you have to reduce the angle of tilt by moving the tilt bolt to the bottom hole so that the lower unit dives deeper, and if the boat goes nose-in, creating a big wave, you have to increase the angle.
A full boat requires more thrust to lift, so the angle may be different from that used for solo fishing. Experiment with the positions of a stubborn bolt, making short runs until you find the perfect position for your conditions.
⚠️ Attention: Never change the position of the thrust bolt of the trim while on the move or with the engine running, this can lead to a sudden change in course and the operator falling overboard. All adjustments are made only in the parking lot with the engine silenced.
When you pick the angle of the trim, watch the jet of water coming out of the cooling control hole. If the jet becomes sluggish or intermittent when you add gas, maybe the water intake is taking in air, try lowering the motor below or changing the angle.
Motor fastening to the transom: bolts or rods?
There are two main ways to fix the motor on the transom: with rods (clamps) coming in the kit, or through through bolts. Strubs allow you to quickly remove and install the motor, which is convenient for transportation and storage. However, for powerful engines (usually 10 hp and above) and when operating actively on the wave, a bolt connection is preferable.
When using rods, you need to monitor the tightening force. Insufficient puff will lead to the engine slipping, and excessive puff can damage the coating of the transom board or deform the soft attachment elements. Regularly check the tension of the screws of rods during the day, as vibration has the property of weakening them.
The through bolt connection provides maximum rigidity and reliability. To do this, holes are drilled in the transom through which long bolts pass. Between the bolt cap and the transom, wide washers are necessarily installed to distribute pressure. The carving should be protected from water, especially if you plan to walk on salty water bodies.
☑️ Checking of the attachment reliability
Regardless of the method chosen, the use of a safety cable is a mandatory safety requirement: the cable is attached to one end to the dim on the lower unit and to the other to the dim on the boat hull or to the transomb board, which will prevent the loss of the motor in the event of its accidental detachment from the transmolant.
Table of recommended installation parameters
To make the adjustment task easier, we will provide an average of the data that will help you navigate the initial installation, remember that these values are starting values and require individual adjustment for a specific boat-motor-cargo bundle.
| Type of boat/power | Height of anti-cavitation plate | Recommended angle of differentiation | Type of attachment |
|---|---|---|---|
| Boat up to 3.3 m, engine up to 5 hp | 0 - 10 mm below the bottom | Middle (3rd hole) | Strubsins. |
| Boat 3.3 - 3.6 m, engine 5-9.9 hp | 10 - 20 mm below the bottom | Middle/Lower (2-3 hole) | Strubsins/Bolts |
| Boat 3.6 - 4.2 m, engine 15-20 hp | 20 - 30 mm below the bottom | Lower (1-2 hole) | Through bolts |
| Keel boats with deep V | Underbody or higher | Middle (3rd hole) | Through bolts |
Why is it important to use stainless furniture?
In constant contact with water, especially salt, conventional steel rusts very quickly, not only does rust spoil the appearance, but it also eats away at the thread, making it impossible to dismantle the motor, and oxides can jam the movable mechanisms of adjusting the trim.
Typical errors and troubleshooting
Even experienced water-engineers sometimes have problems after installation. One of the most common mistakes is to let the vibrations go. If the motor vibrates more than usual, check if the screw is touching the transom or the protection elements, and the density of the lower unit to the board. The gaps can cause resonance.
Another problem is that the engine is overheated, and if the temperature rises faster than normal after installing the engine, check if it is too high, if the water intakes are completely submerged even when rolling on corners, and if the exhaust gases are not sucked into the cooling system due to the wrong angle.
If the boat is not going well on the planing and "sniffs", try to change the balance. Move passengers or cargo closer to the nose or to the stern. Sometimes the problem is not the engine, but the weight distribution. Also check the condition of the propeller: chipped blades can cause severe vibration and loss of traction.
⚠️ Attention: If you hear a knock or feel a sharp vibration immediately after installation, immediately turn off the engine. Continued movement can lead to the destruction of the lower unit or engine tear. Check the mount and the lower unit for damage.
The key to successful installation is not static following instructions, but dynamic adjustment to real-world sailing conditions. Don't be afraid to experiment with altitude and angle in the safe zone to find the perfect position for your boat.
Final inspection and maintenance
Once the engine is set and set up, don't rush out to the shore immediately. Make a circle around the waters in different engine modes. Check if the boat is on course, if there are any jerks, if the cooling stream is stable. Pay special attention to work at low speeds and when the throttle is sharply opened.
Regular maintenance of the anchorage will prolong the life of your boat, periodically lubricate the rubbing surfaces of the transom plate and scabs with graphite or silicone lubrication, which will prevent the metal from boiling and make it easier to adjust in the future, and inspect the transom for cracks or scabs.
Right. boat-mounting It's a skill that comes with experience, and over time, you'll learn to feel the slightest change in boat behavior, and you'll be able to adjust your settings by eye, and remember that safety and comfort on the water depend on little things that are often overlooked.
Do I need to lubricate the contact points of the trunks with the trunk?
Yes, it is recommended to lubricate contact points periodically, especially if a bolt mount is used or the boat stands for a long time without movement, this prevents corrosion and attachment of the metal to wood or PVC. However, the lubricant layer should be thin, so as not to create a sliding effect when puffing.
Can I use homemade transom plates?
You can use homemade elements, but only if you're confident in their strength and hydrodynamic properties. If you're not properly designed, a plate can put an excessive load on the transom or disrupt the hydrodynamics, which will lead to instability. Factory solutions are tested and safer.
How often should I check the tightening of the mounting bolts?
The first test should be done after 15-20 minutes of operation of a new or newly installed engine, then before each release to the water and after each long distillation, Vibration is the main enemy of threaded joints, so regular monitoring is mandatory.
What if the screw is constantly getting air on the turns?
This is a sign that the motor is too high or the angle of the differential is too high (the nose is too high). Try to lower the motor one division down or reduce the angle of the lower unit tilt. Also check if the balancing has been knocked down due to the shifting of the load in the boat.