Idea to use motor-block The availability of land-processing equipment, spare parts in any hardware store, and relatively low cost make this one of the most attractive options for budget motorization, but simply shifting the unit from wheels to transoms is just the tip of the iceberg.
The main difficulty lies in the fact that petrol-engineIt's designed to work horizontally on the ground, and it requires a lot of adaptation to work on the water, and you have to deal with the torque transmission, the cooling system, the exhaust, and most importantly, the safety of the attachment. boat-sweeperThe wrong approach can lead not only to the breakdown of expensive equipment, but also to an emergency on the water.
In this article, we will discuss in detail all the stages of reworking, from selecting a gearbox to the final setup. carburetorYou'll learn which models of motorblocks work best, how to make a reliable mount, and why you can't just weld the shaft to lower unit. boat-engineA one that will last for years.
Choosing a power plant: which motor unit is suitable
The first step is to carefully select a donor, and not every engine from the outside is a good one. cultivator The best choice is four-stroke engines with horizontal shaft output, because they are easier to adapt and have more resource. Two-stroke analogues, often found in older models, run on a mixture of gasoline and oil, which creates unnecessary smoke and requires constant cooking of the fuel mixture.
When choosing, pay attention to the power and volume of the engine. For a light inflatable boat or a small metal flat-bottom, a unit with a capacity of 5-7 horsepower is enough. If you plan to install it on a heavier vessel, you should consider options with a power of 9 hp and above.
Special attention should be paid to the lubrication system. Motor units often operate in a tilt when plowing, but on a boat the angles of roll may be different. Make sure the model you choose has an oil spray system that works effectively at rolls up to 25-30 degrees.Otherwise, the risk of jamming the piston group in stormy weather increases many times. Honda, Loncin, Lifan They have proven themselves to be the most reliable in this niche.
- 🛠️ The presence of a horizontal shaft greatly simplifies the connection of the gearbox.
- ⚖️ The weight of the engine should match the load capacity of your boat.
- 🔧 Availability of remixes and consumables in your area.
- 🌬️ Air cooling requires free air access, which must be taken into account when layout.
Selection and adaptation of the reducer
The most technically challenging part of the project is the alignment of the engine speed of the motorblock and propeller. Internal combustion engines develop maximum power and torque at high revs (usually 3000-3600 rpm), whereas the propeller operates efficiently at speeds up to 1000-1500 rpm. Direct connection will lead to cavitation of the screw and no thrust. gearbox It is an essential element of the design.
Most often for these purposes, gearboxes from motoblocks are used (for example, models of the RM-400, RM-500 or analogues from the Neva, CascadeThey already have the necessary gear ratios (usually around 1:3 or 1:4) and are equipped with an output shaft for the rotor installation. The main task is to properly connect the engine shaft and the gearbox input shaft, often using a belt gear or chain gear, which allows smoothing jerks and vibrations.
When you use a belt, it's important to pick up the right pulleys, and the drive pulley on the engine should be smaller than the gearbox, which not only reduces the speed, but also creates an effect. friction: when the screw is jammed, the belt will simply slip, saving the engine and gearbox from breaking down. The chain gear is more reliable, but requires constant lubrication and protection from water, since moisture will quickly disable the chain.
Can I use a VAZ gearbox?
Theoretically, it can, but it will require a major overhaul of the body and lubrication system, gearboxes from the motor units are structurally closer to the conditions of operation and easier to install.
It is important to ensure the tightness of the coils of the gearbox. Staff seals are often not designed for permanent immersion in water, even partial. It is recommended to replace the coils with better analogs or use an additional system of lubricating the coils with a thick lubricant. It is also necessary to provide for the possibility of draining the oil to replace it, since in the aqueous environment the oil resource may be reduced.
Manufacture of transom fixings
The attachment of the engine to the boat is a safety issue. A homemade structure must withstand not only the weight of the engine, but also significant vibrational loads, as well as jerks when hitting a wave. The use of wooden bars or wire is strictly prohibited. aluminum or steel pipe with a wall thickness of at least 3 mm.
The mounting design is usually an U-shaped frame that covers the transom of the boat. The geared engine is attached to the movable part of the frame, which allows you to adjust the height of the screw immersion and the angle of inclination of the lower unit. Standard rods from the motorblocks, reinforced with additional bolts, are used to fix. All threaded joints must be processed. threader Or have grover washers.
⚠️ Attention! When designing a mount, consider the center of gravity. Shifting the engine too high or too far back can disrupt the boat's differentiation, leading to yawing or even tipping the vessel over at low speeds.
For PVC inflatable boats, protective linings should be used on the metal contact points with cylinders. Sharp edges of metal can damage the cylinder material when vibrating. It is best to use rubber pads or special plastic linings. Metal parts of the attachment that contact water should be painted with anti-corrosion paint or made of stainless steel.
☑️ Checking of the attachment reliability
Cooling and exhaust system
Motor units have air-cooled engines. On the ground, the flow of air from the fly fan effectively removes heat. On water, especially at low speeds or calm, this may not be enough, because a "heat bag" of hot air is created around the engine. Therefore, you need to ensure forced air flow or use casings that guide the flow.
The exhaust system also requires attention. In the motorblock, the muffler is horizontal or at an angle. When mounted on a boat, it is important to place the exhaust pipe slice above the water level to exclude the use of the exhaust pipe. hydrostroke If you get water into the cylinder through the exhaust tract, it's guaranteed to knock the engine out, and some craftsmen take the exhaust out through the hollow shaft of the propeller, or make a separate pipe that points upwards.
To improve cooling, you can install an additional electric fan aimed at the cylinder head, or arrange the intake of off-water to cool the exhaust gases (as in water engines), but this requires a complex reworking of the muffler. The easiest way to monitor the temperature of the engine and not let it run for a long time at maximum speeds without loading.
- 🌡️ Control the temperature of the cylinder with your hand (cautiously) or thermosensor.
- 💨 Make sure that the hot air is free from the casing.
- 🌊 The exhaust pipe cut should be above the waterline by at least 15-20 cm.
- 🛡️ Use a sparkler on your exhaust if you are fishing in fire-prone areas.
To protect against spray and improve blowing, the manufactured aluminum sheet casing leaves holes for cool air intake in front as the movement progresses.
Fuel system and management
The regular gas tank of the motorblock is often low and has no protection against water. When installed on the boat, it is better to use a remote fuel tank located in the bow for centering, or reliably shield the regular tank. The fuel hose should be of high quality, benzo-resistant and have no bending. Be sure to install fuel-filter rough and fine cleaning before the carburetor.
The engine is controlled through the gas cables. The regular levers on the motor unit engine are inconvenient to use from the humming wheel. It is recommended to put the throttle control cable on the handle of the hummel or on a separate sector of gas in the cockpit, which will allow you to adjust the speed with one hand without releasing the hummel.
The ignition in motor units is usually electronic (magdino), does not require battery power. However, for the operation of sensors or additional equipment (navigator, sonar), the battery will still be needed. It is better to place it in a sealed compartment. smothering The engine (check) should be brought to the operator so that when falling overboard the engine is dead automatically.
| Parameter | Motorblock (standard) | Adaptation for the boat |
|---|---|---|
| Position of the shaft | Horizontal. | Horizontal (through 90° gearbox) |
| Cooling | Airborne (natural) | Air (forced/directed) |
| Lubricant | Spraying | Level control at roll |
| Management | Levers on the hull | Cable to the tiller/sector |
| Fuel. | AI-92 + oil (two-stroke) / AI-92 (four-stroke) | AI-92 (with stabilizer) |
The main difficulty of adaptation is not the engine power, but the organization of reliable torque transmission and protection from water.
First launch and break-in
After the entire structure is assembled, take your time to go out into the open water. The first run is better done on land, fixing the boat or putting the engine on the stand. Check the ignition system, make sure there are no vibrations that can weaken the attachments. Check the work. gearbox idling - it should not be too warm or make extraneous noise.
The engine should be run in water in a gentle mode. The first 2-3 hours of operation is not recommended to give more than 50-60% of the maximum power. This will allow the piston group and gear bearings to wipe themselves. During the break-in, constantly monitor the temperature of the engine and gearbox. When overheat, immediately slow down.
Check the condition of the fasteners regularly. Vibration is the main enemy of homemade structures. After each fishing, hold out the engine and gear bolts. Also remember to flush the cooling system (if it is watery) and lubricate the moving parts. solid-greaseresistant to water washing.
⚠️ Attention! Never leave the engine running unattended. In the event of a screw jamming or loss of control, the boat may start to move uncontrollably in a circle or sail away.
Frequently Asked Questions (FAQ)
Can I put the engine from the motoblock on an inflatable PVC boat?
Yes, you can, but the weight of the engine will be critical: motorblocks are heavier than specialized outboard motors; you need to calculate the load capacity of the boat based on the weight of passengers and equipment; you also need to use a rigid plywood or aluminum transom seat to distribute the load.
Which screw is better to choose for a homemade motor?
The best solution is to use ready-made propellers with a diameter of 180-220 mm with a pitch corresponding to the engine speed after the gearbox. Often use propellers from outboard motors "Salute" or "Winds", adapting the seat. The screw pitch is selected experimentally to achieve maximum speed without overloading the engine.
Do I need to register a boat with such a motor in the GIMS?
Registration is required if the engine power exceeds 10 horsepower (or 8 kW) OR if the weight of the equipped vessel exceeds 200 kg. Since the engines of the motor units are often more powerful than 10 hp, legally such a motor requires registration and the right to operate a small vessel.
Why does the engine stop when gas is added?
It's probably a problem with the carburetor setting or the jelly clogging, and it could be a lack of air suction (air filter is clogged) or a failure of the ignition system (candle, coil) that's different from the humidity on the boat.