The efficiency of the water jet or screw engine depends on how well it is performed. boat-mounting Many inflatable boat owners make the mistake of thinking that it is enough to simply lock the rods in and start the machine, but ignoring the geometry of the plant leads to loss of speed, fuel consumption and, most dangerously, to accidents on the water.
Incorrect suspension Or the wrong angle of the differential can cause cavitation, where the screw starts to take air instead of water, and not only does it reduce thrust, it also causes the daydwoot to overheat, which in the long run disables the technique. centre-up along the symmetry axis of the boat provides stability of the course and predictable behavior of the vessel when entering the plane.
The installation process requires attention to detail, as the transom of the boats from the PVC Unlike metal or fiberglass, inflatable sides require a uniform load distribution. In this article, we will discuss a step-by-step algorithm that will help you avoid typical errors and adjust the engine so that it gives maximum performance.
Preparation of transoms and selection of fasteners
Before starting physical work, you must make sure the landing site is ready. Tranza It's a vertical slab in the stern of the boat that takes over all the load from the propeller's thrust and the weight of the engine. For PVC boats, it's critical that the transom is rigid and free of backlashes. If you use a removable transmuter, make sure it's securely locked in the cylinder slots and doesn't shift when you press hard.
Particular attention should be paid to the material of the transom board, most often it is multi-layered plywood, covered with waterproof paint or laminate. Surface. It has to be smooth so that the engine rods fit tightly, and if there are irregularities or bloating on the tree, they need to be eliminated, otherwise the engine may shatter when vibrating. fixing-piece The transom itself to the cylinders, since the weight of the engine will fall on this zone.
⚠️ Warning: Never set the motor on a soft or sliding transom, and excessive vibration will quickly destroy the PVC structure in the attachment areas, leading to depressurization of the boat directly on the water.
The fixation uses regular rods that come with the engine, or a special overhead transom-layer for high-performance models. It is important that the contact surface of metal and wood (or plastic) is clean. Dirt, sand or residues of old lubricant can play the role of an abrasive or, conversely, a slippery layer, reducing friction where rigidity is needed.
Do I need a sleeve for powerful motors?
If the engine power exceeds 5 hp and the boat design involves the use of a removable transom, it is strongly recommended to use a transom timber or reinforced lining. This distributes the pressure of the strubccines over a large area, preventing the soft elements of the structure from pressing.
Centering of the motor along the axis of symmetry of the boat
One of the most common mistakes of beginners is to install the engine with a shift from the central axis. Symmetry And here, the key is that if the motor is to the left or right of the center, the boat will start to move away even when it's going straight, and you have to constantly compensate for that with a tiller, which creates unnecessary water resistance and tires the operator.
For fine-tuning, use an imaginary line running along the diametric plane of the vessel from the nose to the middle of the transom. lower unit The motor should be strictly parallel to this line, and you can visually check this by standing behind the boat on the shore and looking along the keel. If the engine is curved, loosen the rods and move the unit to the ideal position, then tighten the mounts with the required force.
The shifting of the center of gravity also affects the flank In lateral winds, improper alignment can make things worse, making the boat less stable, especially in narrow inflatable boats where stability is limited, and a properly centered motor ensures that the propeller's thrust is directed backwards, ensuring maximum efficiency.
Use a building level or laser pointer to position the motor precisely relative to the keel, which will take a couple of minutes, but save you hours of nerves when you're driving a boat on the water.
Adjustment of the height of the suspension of deidvut
The height of the engine installation relative to the lower line keel It's a parameter that's often ignored, but it has a direct effect on speed. If the motor is set too low, lower unit creates additional water resistance, brakes the boat, and if it's too high, the propeller starts to capture air, especially when you're cornering or accelerating.
The optimal position is considered when the anti-cavitation plate (horizontal plate above the screw) is on the same level with the bottom line of the boat or slightly lower (by 1-2 cm). For flat-bottomed boats (flat-bottomed) plate should be strictly level with the bottom. lease or keeliness, it is permissible to lower the engine slightly lower so that the screw works in a calm flow of water.
Testing the right height is done by experiment. Go out and try to add a sharp gas. If you hear a characteristic roar, and the speed does not increase, the screw breaks into the air. In this case, the engine should be lowered. If the boat is going smoothly, without yaw and with good traction, but you feel that the engine is pressed by water at high speeds, try to lift it one division up.
| Boat bottom type | Position of the anti-cavitation plate | Recommended angle of inclination |
|---|---|---|
| Flat bottom (flat bottom) | Level with the bottom line | 0° (perpendicular to water) |
| Whipped bottom | 10-20 mm below the keel line | 3-5 degrees nose up |
| Boat with redan | At the level of the lower point of the redan | Depends on the load. |
| Heavy loading. | You can lower down by 1-2 cm. | Increase the different |
The main rule of height: anti-cavitation plate should be parallel to the surface of the water when moving, so that the flow goes smoothly, without vortices.
Adjustment of the angle of the different (motor inclination)
The angle of inclination of the motor relative to the transom, or differentiatorIt defines how the boat will behave on the plane. Most PVC boats have an angle adjustment mechanism on their transverses, often through pins or stops, and changing that angle changes the point of application of traction.
If the boat's nose is overly swayed upwards, closing the view and creating sailing, the engine's angle of inclination should be reduced (tilt the lower unit closer to the transom) This will press the stern and lower the nose. Conversely, if the boat goes with its nose down, "blowing" into the wave, lower unit should be swayed further away from the transom, which will raise the nose and lead the boat to clean planing.
Right-minded differentiator It allows the boat to go almost parallel to the surface of the water, which is called a cushion state, where the water resistance is minimal and the fuel consumption is optimal, and you can experiment with angles on calm water, making small adjustments and evaluating the result after each change.
Fixing and safety of anchorages
After exposing all geometric parameters, the final fixation stage begins. Strubsins. They must be tightened with sufficient force to prevent any displacement, but without fanaticism, so as not to damage the coating of the transom. Use the dynamometer key if the motor manufacturer specifies specific values for the moment of puffing.
A critical element of security is tetherIt is a strong cord or chain that is attached at one end to the transom of the boat and at the other end to the lower unit of the motor (usually through a special hole or around a datawood), its task is to keep the motor in the boat in case the strubs can not withstand vibrations and open.
Check the rubber gaskets on the rods regularly, and over time they tan or crack, losing their shock absorbing properties and grip. Replacing these penny parts can save your expensive life. boat-engine from falling into the water and subsequent complex repairs.
⚠️ Warning: Always use the safety rope! No, not even the most expensive system of strubkins, gives 100% guarantee against vibration unwinding over a long distance.
Diagnostics and checking of settings on water
The final stage of the setup is a test run on the water. Go out into the water area with all safety measures, be sure to wear it. lifejacketThe initial check is done at low speeds: make sure the boat goes straight without constant thrustering.
Then slowly increase your speed to maximum. Watch the flow of water coming out of the screw. If you see a lot of bubbles and foam and the thrust falls, that's a sign of cavitation. In this case, turn off the motor, check the height of the suspension and the presence of foreign objects on the screw. Also pay attention to the temperature of the engine: if it runs at the limit because of improper water intake, it will be noticeable by the nature of the work.
A perfectly tuned motor allows the boat to go smoothly, keep a steady course and develop passport speed. If you feel the vibration of the hull or the hummel, double check the tightening of all the bolts and the angle of the differential. Small adjustments can dramatically change the comfort and safety of your walk.
☑️ Checklist before getting on the water
How often should I check the puff of rods?
It is recommended to check the puff before each step, especially during the first hours of operation of the new motor or after changing the transom. Vibration is the main enemy of threaded joints. Also, repeat the check after the first 15-20 minutes of operation at high revs.
Can I use wooden pads for rods?
You don't want to use regular wooden bars, because they can absorb water, swell and change geometry, which will weaken the attachment. If the transom is uneven, it's better to use special rubber pads or level the surface of the transom. In extreme cases, use solid wood that has been treated with water-resistant varnish, but this is a temporary solution.
What to do if the motor blows into the air on turns?
This is a classic sign of a suspension that is too high or a propeller that is not sufficiently deepened. Try lowering the engine one division down. If that doesn't help, maybe the propeller is wrong (too big a step for a given boat) or you need to install a hydrofoil on a lower unit to press the stern.
Does the weight of the passenger affect the engine angle setting?
Yes, it does. The more weight a boat has (passengers, cargo), the deeper it sits in the water. When fully loaded, you may need to change the angle of the trim, or even the height of the suspension, to compensate for the change in the waterline and the center of gravity. Always test the settings when you are typically loaded.