Do-it-yourself boat electric motor. Creating a homemade electric motor for a boat Homemade electric motor for an inflatable boat blueprints

Many fans of fishing on the "big water" prefer to install motors on boats. Making a boat electric motor with your own hands is quite simple and cost-effective. This is due to the large (one might even say exorbitant) cost of modern outboard engines. The price of some is comparable to the cost of the car. Buying an old outboard motor that has been used often is not profitable. It costs a lot, but it will take a lot of effort and money to bring it into working condition.

A boat electric motor can be purchased both in a specialized store, and made on your own from various devices and tools.

Principles of operation of electric motors

Despite the development of technology and production, the outboard motor remains a rather expensive thing that not every owner of a small boat can afford. The lower price limit for the cost of a new motor is about 30,000 rubles, while the upper one can reach the same figures, only in dollars. Therefore, a home-made electric motor for a boat based on electric motors from various household appliances is a good solution that will save money. In addition, you will gain good experience in design.

Electric motors have a number of advantages over other types of motors:

1. The electric motor is the most common type of motor and can be found almost everywhere.
2. They make little noise during operation (compared to internal combustion engines), which is especially important when fishing.
3. They are safe to use. Low flammability, non-explosive.
4. Cheapness. Asynchronous motors are the cheapest motors that exist.

Disadvantages of electric motors:

1. The electric motor is afraid of water, respectively, it should not be in the water and it should not be flooded.
2. The speed when sailing on a boat with a motor should be about 7-10 km / h under load. Therefore, the minimum engine power should be at least 1.75-2 hp.
3. You should think about power sources in advance. Since the electric motor requires electricity, you should purchase batteries in advance and prepare a place in the boat for installing them. If funds are available, a generating solar panel can be purchased, which can be installed on top of the batteries and connected to them. Important: the solar panel should not be the only source of energy, it must work in conjunction with batteries (which can be the only source of energy). The weight of the batteries should be taken into account (they are quite heavy) and after installing them, do not overload the boat.
4. Decide on operating conditions. For example, the speed will naturally drop if you swim against the current or wave, as well as with a strong headwind. It is important to determine the purpose of installing the engine. If the main goal is to sail “race” with other boats, then the electric motor will not work for this purpose. In the case of sailing under adverse conditions (wind, wave, current), you should take the engine with a margin of power.

When the necessary technical requirements are formulated, you can proceed to the implementation of the project. It's worth starting with calculations.

How to calculate parameters

The first thing you should pay attention to when calculating engine power is the conversion of units of measurement from one system to another. Often when calculating the power of the power plant on boats, horsepower is used, and the power of all electric motors is indicated in watts. To convert watts to hp. remember that 1 kW = 1.36 hp. or 0.74 kW = 1 hp

To calculate the power, refer to GOST 19105-79. To calculate the power, you should measure the length of the waterline, deadrise, side height and the maximum possible mass of the boat (the mass of the boat + the mass of all passengers + the mass of the engine, power supplies + the mass of equipment and equipment). For most boats, the 1 hp formula will do. per 25 kg weight. For punt boats, PVC and planing boats, the calculation formula is 1 hp. per 35 kg weight. For example, consider the option with a double boat made of PVC.

The mass of the boat is about 25 kg. Weight 2 adults: 80x2 = 160 kg. The mass of the motor, batteries is about 20 kg. In addition, the weight of the equipment is about 15 kg. As a result, there is: 25 + 160 + 20 + 15 = 220 kg. Motor power is 220/35 = 6.3 hp. Let's translate horsepower into watts: 6.3 * 0.74 \u003d 4.66 kW.

The capacity of the battery is calculated by the formula: P/(Ux0.7), where 0.7 is the battery charge factor (since it will not be possible to charge the battery by 100%). Actually, for 5 kW and 12 volts of power, 5000 / (12x0.7) = 595 Ah is required. Round up to 600. This battery will keep the engine running for 1 hour. If there is no battery of this capacity, then you can take 2 of 300 A * h, 3 of 200 A * h or 6 of 100 A * h and connect them in parallel. If it is required to ensure the operation of the engine for a longer time, then the obtained ampere-hours are multiplied by the number of working hours.

Necessary materials

When the calculations are made, you need to prepare all the necessary tools and materials. To make a motor you will need:

1. Electric motor. It can be dismantled from various household tools or purchased from household appliance repair shops. Engines from a screwdriver, drill, grinder, circular saws, etc. can be used. If the power of the selected engine is less than necessary (for example, if you take a screwdriver engine), then you should take 2 or 3 pieces of the same power from several screwdrivers. Several pieces should be connected in parallel, and it is not necessary to mount them on the same bracket.
2. Batteries. Selected by ampere-hours. How to do this is described above.
3. Bracket materials. There can be any. PVC pipes are recommended as they are cheap, durable and easy to work with.
4. Reducer. Can be used with household appliances or purchased separately.
5. Screw (propeller). You can remove it from an old Soviet fan (models with steel screws) or make it yourself.
6. Speed ​​controller. It does not make sense to install it on such a vessel, but if you wish, you should purchase a mechanical one.
7. Clamps. A few pieces for attaching the bracket to the boat.
8. Consumables: glue, self-tapping screws, screws, adhesive tape, etc.

How the work is carried out

The first thing to do is mount to the boat. It is made from clamps, to which clamps for PVC pipes are welded so that the clamp clamp fastens to the side of the boat. A PVC pipe must be inserted into the clamps, inside which the shaft will be located. The length of the pipe depends on the height of the side and should ensure that the propeller is immersed below the waterline (preferably with a margin of 10-15 cm) and raise the engine to a height not accessible to waves. The diameter of the pipe must allow free movement of the shaft. As a shaft, you can use any rod (preferably stainless steel) with drilled holes at the ends. Such a transmission shaft can be mounted on the motor shaft and on the screw axis without transmission links. In this case, it is important to seal the lower end of the pipe with a sleeve.

Next, you need to do the underwater part. A larger diameter PVC pipe (preferably a tee) should be used in which the gearbox with the propeller shaft is installed. You need to fix it to the rack by soldering to ensure the tightness of the docking. The ends of the pipe with the reducer installed are sealed with bushings or a thick layer of silicone (the former is preferred).

The propeller shaft outlet must be sealed. Next, you need to connect the upper and lower gearboxes with a shaft.

At the final stage, a structure is made for installing the engine and gearbox (upper). The structure for installing the engine must be sealed on the water side (so that the engine does not flood), and on the boat side there must be ventilation holes and power supply. Its size and shape depend on the size of the engine and how it is mounted.

On such a motor, you can safely go out on calm water or in a calm sea.

Evgeny Bronov

Reading time: 5 minutes

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How to make a motor for a boat yourself?

With a limited budget and golden hands, you can not only do it yourself, but also drive to it. There are several mechanisms that are not used for their original purpose, from which a solid construction can be obtained. This article will present options for obtaining a homemade outboard motor and manufacturing instructions.

In most houses and apartments you can find an old drill or screwdriver. Even in a new form, they are more affordable than an industrial motor. If they run on batteries and have a button for speed control, then the principle of working with an electric motor is similar.

• The presence of a battery as a power source.
• A propeller with a gearbox propels the craft.
• The engine controls are a reverse button and a speed control knob.

For the most part, factory boat products are sealed, and therefore they allow use in water. This fact is excluded when choosing a drill or screwdriver as a homemade outboard motor, because they are leaky.

But it is worth remembering that the penetration of moisture into the controls of an electric drill is fraught with trouble. The engine will stop and the boat will stop. The advantage is that finding spare parts for a drill is very easy.

Another significant point is that it is not designed to work continuously. This is not very suitable for boat engines. Therefore, it is desirable to create a power reserve in order to avoid overheating of homemade products.

1. You need to start from one hundred and fifty watts and more.
2. In this case, it is realistic to choose a propeller with a diameter of one hundred and thirty millimeters.
3. The total weight of the vessel is no more than three hundred kilograms.

The voltage of a drill and a screwdriver can be different, as well as batteries for them. But the capacity of the latter is not enough to control the boat. Then a car battery that produces twelve volts will do. With the same voltage, it is better to choose a drill.

Of course, a battery of batteries for any voltage will save the situation. But the cost of such a device can be expensive.

To make homemade motors from a drill for boats, you need to assemble a set of fixtures and tools:

If you need to quickly get the propeller, then it is advisable to make a lifting mechanism to control the motor in a vertical and horizontal position.

To create a mechanism, you need to provide the clamps with rings and pass a tube through them. Such an articulated device ensures the reliability of the steering wheel.

Reducer and propeller

The revolutions of the drill are slightly higher than those required for the operation of the propeller. The reducer will adjust the difference.

1. The upper gearbox is able to reduce the speed from one and a half thousand to three hundred. In this scenario, a homemade motor will allow the boat to move smoothly.
2. The lower gearbox is important for the horizontal setting of the propeller. If it is taken from a grinder, it is enough to clamp it in a screwdriver chuck.

To make a screw propeller, you need to select certain segments on the steel sheet. A square of two hundred by two hundred millimeters and a thickness of three is enough. Stainless steel is much more difficult to carve, but is preferred and lasts longer. You can also take a blade from a household exhaust fan.

Holes need to be made in the center of the sheet. They are required for the landing screw. Slots are made diagonally, leaving a circle of thirty millimeters in the center.

The blades should be round and equal. Each one must be turned at a certain angle and direction of rotation so that there is no oscillation of the screw.

A trial "swim" is done in any container with water into which the screw will fit. You can go to a small pond and lower the screw into the water without a boat. Such a test will show whether the motor made is ready for swimming.

A properly assembled electric motor will beat off a trickle of water, but without vibrations. If something went wrong, the design made on can always be brought to mind with the help of a larger angle of inclination of the blades.

Before you make a motor for a boat, you need to understand how it will move with it. It is important to take into account the weight of the vessel with all things, engine power, current strength and operating voltage. The motor power for a rubber boat or PVC should be at least twenty percent more than the load power. This advantage is useful in case of force majeure.

It is advisable to measure the voltage under load and during idling using a special device.

An excellent homemade outboard motor is obtained from a trimmer. Such an electric motor is made simply because of the similarity of the devices.

A trimmer or mower does not need to take anything away and heavily redo it. In particular, the top gearbox remains the same, as does the motor power supply and control system.

The option is considered very profitable and convenient, because the device has a transmission and an engine. It remains to make a mount for the boat, remove the area with the disk and put the propeller. But let's not forget about the shortcomings.

1. It is worth remembering that the motor for a boat from a trimmer has low power. It is difficult for such a device to swim against the current.
2. The outboard motor from the trimmer is ideal for moving on small bodies of water with stagnant water. And this is not always the ultimate dream of outdoor enthusiasts.
3. You will have to get used to the strong noise effect and smoke.

In general, such a home-made outboard motor is not a very cheap option due to the cost of a mower. But if it already exists and defects have appeared in it, it can easily be converted into an engine for a variety of models of floating craft. It is suitable for small boats, a plywood boat can withstand it due to the lightness of the design and is also inflatable.

Homemade outboard motor from a walk-behind tractor

If the previous option is considered low-power, then the device from the walk-behind tractor is the opposite. Earthmoving equipment usually has reliable four-stroke internal combustion engines. Such a do-it-yourself motor for a boat is capable of carrying passengers even against the current at an impressive speed.

True, a decent volume does not allow to put such structures on PVC boats. At least on small ones. The principle of how to make a boat motor from a walk-behind tractor is as follows.

• Together with the cutters, aluminum blades are placed in the same plane with the shaft.
• The blades must be perpendicular to the movement of the vessel. In appearance, these are rectangular plates, half hidden under water. The rest is free to move through the air.
• The device is attached to the hull of the craft and allows it to move easily even in shallow water and reservoirs with a rapid current.

Possible do-it-yourself crafts for a PVC boat

A homemade outboard motor can be built from a ventilation engine or a stove from a passenger car. Or take the car compressor "Gnome".

However, these models have a number of disadvantages.

1. The first option is immersed on the shaft. However, the tightness is broken. We have to think about how to solve this problem quickly.
2. The compressor is considered more powerful and is installed vertically from above. At the same time, it is connected to the screw through an angular gearbox and a shaft.

It is realistic to work with these structures if you have technical experience. Otherwise, it is better to contact a mechanic.

For example, someone who uses boats for a motor, made without anyone's help from plywood, is able to cope with the alteration of a walk-behind tractor.

With all the variety of outboard motors, do-it-yourself PVC made for a ship are acceptable options. According to the reviews, it can be judged that the duration of their work does not differ from the factory ones with competent alteration and assembly.

It is worth remembering that before using it on high water, you need to test the manufactured outboard motor with your own hands. This can be done at least near the shore of the reservoir. In any case, the experience gained will always help when faced with surprises in the operation of electric motors.

Boat anglers will certainly be interested in the simplest homemade boat outboard electric motor, entirely made by hand (Fig. 1).

The design of a homemade boat electric motor quite simple and reliable, cheap and affordable to manufacture. The use of such an outboard electric motor makes it easy, without noise, to maneuver the boat without breaking away from fishing, in particular, to keep the boat in the desired position against the current.

The main elements of the installation are a 6- or 12-volt battery and, respectively, a 6- or 12-volt DC electric motor. The battery can be used from a passenger car.

A - the shape of the propeller in plan (marking); B - the device of the stuffing box and drain plug;
1 - motor shaft with a thread reverse to the rotation of the shaft (to drain water from the stuffing box); 2 - stuffing box cover; 3 - sealing ring (rubber); 4 - pressure washer; 5 - stuffing box (felt);
6 - stuffing box body; 7 - intermediate pressure washer; 8 - drain plug flange;
9 - sealing ring (rubber); 10 - drain plug.

The electric motor must be mounted in a hermetic casing, which can be welded or soldered from sheet metal. To do this, you can use a tin can of suitable size. The outlet of the casing under the motor shaft must be equipped with an oil seal, which would ensure the tightness of the casing. One of the possible options for the seal design is shown in Fig. 2, B.

To drain the leaked water, it is necessary to provide for the installation of a drain plug with a thread and a sealing washer in the lower part of the casing. In the upper part of the casing for connection with the steering column, weld a threaded adapter pipe.

The manufacture of the remaining parts does not present technical difficulties. The steering column is made from a water pipe with a diameter of 0.5 inches. Bend it into the shape of the letter "G". At one end, cut the thread for the casing nozzle, and at the other put on the handle made of insulating material. The steering column is used simultaneously for wiring to the motor.

To attach the outboard electric motor to the stern of the boat, a metal clamp is used, to which the steering column bracket, limiter and stop are welded.

The propeller of a homemade outboard boat electric motor is made of sheet steel or brass 1.5 mm thick.

To secure the propeller to the motor shaft, use a clamp screw hub. Before final assembly, carefully clean the parts with sandpaper and paint with paint for metal. Such a homemade outboard boat electric motor (without battery) is very light and convenient.

Unlike ancient times, when one could only rely on the forces of nature to hope for a tailwind, today it is possible to move on the surface of the water in any direction without significant physical effort and in complete calm.

Thanks to scientists who have produced electricity for humanity and tamed the fire of an internal combustion engine, any boatman can independently attach some kind of motor to his watercraft.

What can a boat motor be made of?

A boat motor can be made from many mechanisms that gather dust in a barn or garage and are not used for their intended purpose.

It often happens that the equipment breaks down, and in order to fix it, you need to spend more than half the cost of a new device. It is much easier in this case to purchase a new device, and put the old one aside and use it as a source of spare parts and various bolts and nuts. It is from such devices that you can make a boat motor.

If such devices are not available, then you can inexpensively purchase such a mechanism in the secondary market. The main thing is that the engine is in good condition in such devices.

Trimmer outboard motor

By minimally changing the design of the trimmer, you can arrange an excellent traction unit for a boat of any design. There is already an engine and transmission in such a device, it is enough to make a mount for the boat, and instead of a bobbin with fishing line or a disk, install a propeller.

Before making a boat motor from a trimmer, it should be understood that the power of such devices is very small, and it is unlikely that it will be possible to move against a strong current.

The trimmer as a boat motor is ideal for use on a lake or pond.

The disadvantages of using this device include a high noise level. In addition, at a low speed of movement, you will have to breathe absolutely all the products of the "vital activity" of this system.

Boat motor from a screwdriver

Outboard motors on electric traction have excellent indicators in terms of noise production and environmental friendliness. You can make a motor for a boat from a screwdriver, but the power of the device should not be less than 300 watts. To transmit torque to the screw, which is located under water, you can use a flexible shaft from the trimmer.

A small aluminum screw from a car fan is used as a propeller, and car batteries with a capacity of 60 Ah are used to ensure a long time for such a device.

The disadvantages of such designs is the need to carry a fully charged car battery with you. The mass of such a part is more than 20 kg. The disadvantages include the limited stroke of such a motor, after the battery is discharged, it will be necessary to manually set the boat in motion again.

Boat motor from walk-behind tractor

The most powerful of home-made outboard motors is considered to be a device made from a walk-behind tractor. The gardening equipment is equipped with hardy and durable four-stroke internal combustion engines, which, when installed on a watercraft,

will allow him to develop a decent speed both with the flow and against it. Such engines have a significant mass and, usually, not used on PVC boats.

The easiest way to install an outboard motor of this design is to minimally alter the main structure. It is enough to attach a walk-behind tractor to the boat hull, and install aluminum blades instead of cutters. The blades must be located in the same plane with the shaft, which in this case is perpendicular to the movement of the craft. The blades have the form of rectangular plates, which should be lowered into the water with the lower half, and the upper part should move freely through the air. Such a paddle wheel device will allow you to move at high speed even in places where the depth does not exceed half a meter. A boat engine made from a fast-moving motoblock does an excellent job.

Other options

You can make a homemade engine not only using trimmers and screwdrivers as a basis. If there is a desire to design an outboard motor on your own and there is a significant amount of time and money, then any technical device equipped with an internal combustion engine or driven by an electric motor can be used as a power unit.

Many craftsmen put engines from motorcycles on the boat. In this case, it is possible to regulate the speed of the propeller by shifting the gearbox. Powerful 12-volt motors, which are used in various mechanisms, can be successfully used as boat engines.

We make a boat motor with our own hands

It is not difficult to make a boat motor - it is enough to prepare all the parts necessary for this and assemble the device in such a way as to exclude the possibility of damage to the boat during the operation of such a unit, and ensure safety for people.

The easiest option for making a homemade motor from a trimmer. For assembly, you will need the following materials and tools:

1. Trimmer.
2. Spanners.
3. Pliers.
4. Screwdriver.
5. Bulgarian or hacksaw for metal.
6. Drill and twist drills for metal.
7. Stud 12 mm.
8. Vice.

To make a working version of the outboard motor, you will need to purchase a trimmer. You can use any model, but the more powerful the device, the boat will have higher speed characteristics

Making a propeller is the first thing to start with. For the screw, a dural plate with a size of 100 - 30 mm is used. Exactly in the middle of such a plate, it is necessary to make a hole for installing it on the trimmer shaft. The hole diameter depends on the thickness of the gearbox shaft and is usually 17 mm. Before bending the duralumin plate, it must be annealed. Then, with pliers, each side is slightly bent so that during axial rotation of such a plate, its step is no more than 10 mm.

Then the reel is removed from the mower and a screw is installed in its place. It is necessary to tighten the nut well so that the screw does not turn during operation. The trimmer discs are fixed with a nut with a left-hand thread, so when the outboard motor is running, you can not be afraid of losing the screw due to unscrewing the nut.

Then you need to make reliable fasteners with which the trimmer will be installed on the boat. On the body of the trimmer at the junction of the two halves there is a ring for attaching the belt. It is this part that will connect the trimmer body to the boat. It is necessary to make a mount that will securely connect the hull of the boat to the "eye" of the trimmer. For this purpose, you can use a mechanical meat grinder, in which the lower part is separated using a grinder or a hacksaw. Then a hole with a diameter of 12 mm is made in the body of the resulting clamp. The hole must be located in the transverse plane of the screw clamp.

From a metal stud with a diameter of 12 mm, it is necessary to cut a piece 100 mm long. On the one hand, this segment of the stud is slightly flattened and a hole with a diameter of 6 mm is made in it. A 6 mm bolt is threaded into this hole, on which the “eye” of the trimmer is installed. The bolt must be tightened with a self-locking nut.

The process of installing the motor on the boat occurs in the following sequence:

• the mount is installed on the transom and securely fixed with a threaded connection;
• a homemade outboard motor is installed in the mounting hole.

The motor can be started and steered by holding the boat motor body evenly, and if necessary, tilt it in the opposite direction of the boat turn.

Reducer and its effect on work

The use of a gearbox for a boat motor allows you to change the direction of axial rotation. The gearbox changes the speed of rotation of the shaft several times, which has a positive effect on the working life of the engine. When equipped with a gearbox for an outboard motor, you should adhere to the golden mean and do not install a device with a large gear ratio. Failure to do so will result in excessive fuel consumption, slow boat speed, and engine overheating. The surest way to find the optimum gear ratio for a given motor is to test several different devices. If during operation there is no excessive load, which manifests itself in the impossibility of quickly gaining high speed and the speed of the watercraft is quite high, then this gear ratio can be considered optimal for this engine.

An average gear ratio that will work well with many internal combustion engines used as a boat motor is 1/5.

Electric motors can be used as traction for boats without a gearbox. The traction force of such devices is sufficient to work stably in the mode of direct transmission of torque to the propeller. An excellent engineering solution is to use an electric motor underwater. With this arrangement, the screw is fixed directly on the motor shaft.

Homemade motor with gearbox

It is not easy to make a motor with a gearbox on your own, but this design will allow you to change the speed of the boat and change the traction characteristics of the propeller. This design is convenient when trolling, in addition, switching to a lower gear will allow the boat to move more efficiently against strong winds and with a significant load.

The most compact version of the engine that you can make yourself is a device that uses a two-stroke engine from the Karpaty moped as a power unit. Such a device will have only two speeds, but this is quite enough.

The engine is mounted on a self-made frame, which is a cut off part of the moped frame. The right cover and the drive sprocket are removed, and a small gearbox is attached to the shaft, to which a standard “leg” from the Whirlwind outboard motor is then attached, through which the torque is transmitted. All parts must be installed in such a way that the design is as balanced as possible, otherwise a noticeable distortion will be felt during movement, and when using such an engine with a PVC boat, the boat may capsize. The control handle of such a device must be at least 0.5 length, otherwise, while driving the boat, you can get burned from a hot engine and muffler knee.

The advantages of such a boat motor are very quiet operation, low fuel consumption and the ability to switch to a lower gear when necessary.

Passion for outboard motors came to me relatively recently, in 2014. Although I graduated from the motor department of the Moscow Aviation Institute and by my main profession I work as an aircraft engine design engineer, I mainly satisfied my passion for amateur technical creativity by improving the UAZ-"loaf" converted into an off-road "camper" for family trips around the country. We have spent every vacation since 2000 on trips with this car. And in 2013, while in Karelia and the Murmansk region, we suddenly realized how much we were losing without having at least a small watercraft with us. The most beautiful lakes of the Kola Peninsula (Imandra, Umbozero, Lovozero) can only be reached “pointwise”, and at the same time there is a risk of being near the dachas of local residents. Therefore, the first thing we did upon returning home was to purchase a small boat "Stringer-265" of the "kart" class.

Making a choice, we deliberately abandoned the "inflatable" so as not to take up useful space inside the "home on wheels", already clogged with equipment, food and other camping belongings. A double plastic boat weighing only 40 kg, designed for an outboard motor with a power of up to 5 hp, is quite easily thrown onto the roof of a car.

The next acquisition was a four-stroke outboard motor Honda BF2 with a power of 2 hp. It was far from new and required a bulkhead. That's when I "hooked" on a new "technohobby".

Surprisingly, fiddling with a boat engine turned out to be much more pleasant than with a car engine. You sit at the table under the lamp, all the details are small and neat, the threads are no more than MB. You get "pleasure in its purest form"!

Then the Veterok-8 was restored, and then their own designs, as a rule, belonging to the category of “hybrids” went: modern motor heads mounted on the “legs” of old domestic engines. For budgetary reasons, the main objects. participating in my research, were products made in China.

The motors were assembled, disassembled, changed, so now I myself find it difficult to say how many there were in total. In any case, today in the pantry there are seven complete engines that can be called homemade. There is even a rather exotic option with a paddle wheel for shallow rivers. I hope that the experience I have accumulated will be useful to other self-made water motorists - readers of the "Modeler-Constructor", especially since this is my desktop magazine, starting with No. 4 in 1966.

FROM FIELD TO WATER

My first full-fledged home-made was a two-stroke trimmer engine mounted on the “leg” of an old Sputnik (a folding version of the smallest Soviet PLM Salyut with a power of 2 hp). I wanted to get the most compact and lightweight, but at the same time a sufficiently powerful motor. Accordingly, the motor head was chosen the most powerful of the then available on the domestic market.

Inexpensive and light Chinese motor heads can be widely used in the work of aircraft builders. You can work with them literally on the kitchen table!

In 2014, it was a "two-stroke" with a displacement of 52 cm1 from the Carver GBC-052 lawn mower. The power declared by the manufacturer was as much as 3 hp. (as it turned out later, this was greatly exaggerated).

Here it is necessary to make an important technical digression about the general features of the so-called trimmer internal combustion engines, which are now widely used not only on lawn mowers, but also on motorbikes, motorized scooters, and even on large aircraft models. All of them are single-cylinder, have a high operating speed (up to 9000 rpm), forced air cooling with an impeller made in one piece with the flywheel, the same type of Walbro membrane carburetors that allow operation in any position, the same "standard" electronic ignition and automatic centrifugal coupling of two main sizes (with diameters of driven drums 54 or 78 mm). Interestingly, the high speed, air cooling and centrifugal clutch are also inherent in the Honda BF2 outboard motor, which was created on the basis of the Honda GXV57 general-purpose agricultural engine (more powerful outboard motors of the company are already built on the basis of car engine blocks).

Trimmer engines are two-stroke and four-stroke. Currently, the line of Chinese "two-stroke" is wider. Most of them, regardless of the brand, come from one Mitsubishi prototype and have factory designations in the style of the Soviet military-industrial complex, consisting of a set of numbers and letters: 1E34F with a displacement of 26 cm3, 1E36F - 33 cm3, 1E40F - 43 cm3, 1E44F - 52 cm3 and 1E48F - 63 cm3. In addition, there is a rare "heavy duty" version of the 1E48F with a displacement of 72 cm3.

The main characteristics of two-stroke trim motors are shown in the table. Their power is indicated according to manufacturers, but since they sometimes allow themselves to significantly overestimate it, it can be approximately assumed that every 25 “cubes” of working volume correspond to somewhere in one real “horse”. In the same table, for comparison, the characteristics of a modern two-stroke Japanese-made Maruyama NE500 engine with a displacement of 50.2 cm3 are shown. Due to the significantly higher rotational speed, it has better power characteristics with less weight. However, its price is three times higher than any "Chinese", therefore, it is hardly suitable as a source material for a homemade product.

Interestingly, trimmer engines have a reserve for increasing power. As already noted, they are all equipped with Walbro diaphragm carburetors with two adjusting screws: an idle screw and a screw for the quality of the fuel mixture at high speeds.

If the use of the first is prescribed in the instruction manual, then it is not recommended to touch the second outside the repair shop. This is no coincidence, as the lawn mower often operates under conditions of abrupt load release at high RPM, when the cutting head is lifted into the air. And if the mixture quality screw is not adjusted correctly, then the motor can “run wild”. However, such a regime is completely uncharacteristic for PLM, the propeller of which is constantly immersed in water. Therefore, you can do individual fine-tuning of the quality screw. It is tightened (slightly!) to the stop, and then gradually turns away by 1.0-1.5 turns. This adjustment achieves the maximum speed at maximum power and at the same time provides easy starting. The real quantitative increase in power is unknown to me, but it is noticeably noticeable by the speed of the boat.

When docking the motor head with the gear part ("leg") of the outboard motor, two main issues always arise: 1 - manufacture of an adapter plate between the stern tube and head attachment points; 2 - manufacture of an adapter between the crankshaft of the engine and the vertical shaft of the outboard motor. In the case of a trimmer engine, a centrifugal clutch is installed between the crankshaft and the vertical shaft. Sometimes, however, some do-it-yourselfers remove the clutch, which allows you to transfer torque to the screw at low engine speeds (and catch fish "on the track", for example). But I am not in favor of such a solution. There are several reasons for this. Firstly, the centrifugal clutch and air cooling of the engine make it possible to start it on the shore even in a horizontal position, which is very convenient in bad weather or in fast currents. Secondly, the clutch smooths out torque peaks and thereby significantly improves the reliability of the power train. Thirdly, a two-stroke trimmer engine is in any case poorly suited for trolling, as it is extremely unstable at low speeds.

The figure shows the adapter plate between the deadwood of the Salyut/Sputnik engine and the "standard" trim clutch with a diameter of 78 mm. Material - alloy D16T. Dimensional tolerances are not indicated deliberately, since the markup is best done "in place". Pointed studs Mb are installed in the holes of the joined parts, and then the centers of the reciprocal holes are determined by light tapping of the hammer. Part of the adapter plate serves as a carrying handle - a necessary element of any outboard motor.

The peculiarity of the deadwood "Salute" is that one of its holes with a diameter of 6 mm coincides with the corresponding hole of the "bell" of the clutch. Therefore, the motor head must be rotated at an angle of about 5 degrees relative to the plane of symmetry, which is almost imperceptible from the outside.

My experience shows that with the right blank, it is quite possible to make such an adapter plate at home or in a garage without the use of a milling machine. Enough electric jigsaw with metal files and an electric drill with a set of drills and crowns.

- You can make an adapter plate even in a home workshop without the use of milling
- Installation of a Chinese trim motor head on the “leg” of the Sputnik outboard motor is carried out using an adapter plate

Now let's move on to the clutch. This assembly connects a segment of the splined shaft of a brush cutter with a diameter of 8 mm (it happens that shafts with a diameter of 7 and 10 mm are found in them) and a vertical Salute shaft, the tip of which has an inner square of 9x9 mm. For joining the shafts, a tool adapter VI "-3/8" was used. The shank of the splined shaft is ground with a grinder to fit a 6.35x6.35 mm (1/4") square. With due care, this is a simple operation. And the adapter shank must be reduced from a 3/8" square (9.5x9.5 mm) to 9x9 mm. The most important and weak link of such a coupling is the place where the shafts are directly joined. If there is a backlash in it, then it will inevitably break. Therefore, a tight fit "on hot" is necessary here. The square shank of the shaft is ground so that it barely fits into the groove of the adapter, but no more. Then the adapter is heated to a temperature of 150 - 200 degrees (not hot!), and the assembly is assembled in a vice with light hammer blows. The spring is necessary in order to remove the axial play of the vertical shaft.

Unfortunately, it is impossible to accurately calculate the strength of such a miniature joint. In a single-cylinder internal combustion engine, peak torque values ​​can exceed the average values ​​taken from the external speed characteristic by 2-3 times, which, when cyclically repeated, can lead to fatigue failure in a dangerous section. Specific values ​​for the peak torque are difficult to determine because the damping effect of the flywheel and clutch is unknown. An approximate calculation in accordance with the well-known reference book of the designer V.I. Anuryev gives shear stresses close to the fatigue strength of steel 45. It remains to be hoped that the Chinese make a forged spline shaft from stronger alloy steel.

However, now it is already possible to refer to the fact that the described design of the transition coupling has been tested by the successful operation of the motor for two seasons. And it turned out to be not the weakest link at all. The propeller pins were cut off, the clutch linings were worn out, but this clutch, although I made a spare just in case, worked without breakdowns.

To control the motor, I decided to use the regular handle of the lawn mower. It is convenient in that all the necessary elements - the gas key and the ignition switch - are concentrated in one place. There is a throttle key lock corresponding to approximately 90 percent power. Dural tiller - sliding, made of a telescopic brush for washing windows. It is fixed with one M8 thumbscrew and can be easily removed during transportation.

The solution is rare for outboard motors, but I consider it successful. Small changes were made in the underwater part. The impeller of the water cooling pump was removed from the drive shaft of the gearbox, and its cavity was filled with Litol to increase the sealing of the gearbox. Unnecessary exhaust pipe cut to improve streamlining.

- Tiller-sliding, made from a telescopic brush for washing windows. The gas key and the ignition switch are located on the handle of the lawn mower.
- Homemade PLM Honda BF2. Pay attention to the size of the propellers.

The disadvantage of "Salyut" can be considered the actual absence of an anti-vibration plate (AKP), which can lead to air leakage from the propeller, especially with increased engine power. I had to make the automatic transmission myself. Material - aluminum alloy AMgb. The plate is installed between the stern tube and the gearbox housing instead of the standard gasket. The design is inspired by the shape of a fish tail.

One of the most important elements of the outboard motor, which determines the effectiveness of the "boat-motor" complex, is the propeller. Currently, there are two left-handed propellers for Salyut. The first of them is a regular two-bladed one, with a diameter of 140 mm and a pitch of 118 mm. Due to the characteristic saber-shaped blades, it is characterized by a reduced tendency to wind grass. There is also a more “correct” three-blade propeller BAV-9 from the point of view of hydrodynamics, developed by the multiple record holder of the USSR in powerboating A.V. Barinov for "Salyut-2.5" (the last mass-produced modification). Its diameter is 158 mm. pitch 90 mm. Both of these screws can still be bought in Moscow in a store at the Salyut aircraft factory.

My experience has shown that both propellers are excellent for PLA with trimmer heads. I use a two-bladed one as a high-speed for a light boat with one person on board. Three-blade - cargo, when the load is two or more people. Practice has also shown that the standard Salyut safety pin with a diameter of 3 mm cannot withstand power increased to 2.5-3.0 hp. It is necessary to drill the propeller shaft up to 4 mm.

As follows from the above photos, the appearance of the structure is quite decent. In my opinion, there is harmony and lightness in it, which is absent in the “hybrids” with four-stroke engines from lawn mowers. When folded, it is generally unrivaled. Folding touring outboards of this type were produced only in the USA in the 1950s and 60s and are not found on the market today.

It is possible to replace the power plant with a homemade PLA even in the field. This requires the most common tools h half an hour of time. Tests of the assembled motor were carried out on Istra, Oka and on Lake Onega in the summer of 2014. The rival was Honda BF2. My design was significantly lighter (8.9 vs. 12.4 kg), more compact and seemingly more powerful (3 hp instead of 2.3 hp declared according to the "passport"). However, the “Japanese” accelerated a boat with one person (total displacement of about 150 kg) up to 8-10 km / h, and a more powerful home-made - only up to 6-8 km / h. There was an unfortunate feeling that you invent, you try, you think with your head, you work with your hands, but the Japanese still get better...

The thought arose, as it later turned out - erroneous, that the propeller was incorrectly selected. Indeed, the propeller on the Honda is noticeably larger: diameter 184 mm, pitch 120 mm. Attempts were made to use more "heavy" propellers from imported motors. There were only two such suitable, left-hand rotation with a sleeve with a diameter of 12 mm - a very roughly made ppasti from the Chinese Troll 2.5 (diameter 190 mm, pitch 102 mm) and from the discontinued 4-horsepower American Johnson 3R (diameter 190 mm, pitch 152 mm). The second showed the best results, and I began to use it as the main one. But that was a fucking mistake! After about ten hours of operation, the clutch jammed. An autopsy shows that its friction pads are worn down to metal, and the bearings of the driven drum are clogged with wear products. The performance of the bypa motor was restored by replacing the clutch linings, washing the bearings in kerosene, and Barinov's "native" screw was returned to its place.

The reason for the breakdown turned out to be that the hydrodynamically “heavier” propeller caused constant slippage of the clutch, which I did not notice in time when it heated up. Conclusion: when using motors with automatic centrifugal clutch, it is necessary to monitor its temperature and, by choosing the right screw, prevent overload. The “lack” of speed can be explained simply - there were big discrepancies between the declared and real capacities of the Chinese head, which caused confusion.

At the same time, in the beginning of 2014, the Forward FBC-720T “heavy duty” gas trimmer with a motor head with a working volume of 72 cm3 and a declared power of 4.7 hp appeared on sale. In fact, about 3 hp, of course, but it was impossible to refuse such a tempting offer! Motokosa was purchased on the last day before leaving for Karelia. Here one of the main advantages of trimmer motors manifested itself: the replacement of the power plant in the field took no more than an hour. And everything fell into place! The speed of the boat with one person on board was 10-12 km/h, and with two - 8-10 km/h. Honda BF2 was finally defeated and soon sold, as it was no longer of technical interest to me.

BY SCREWS!

Having closed the season, on long autumn evenings, I began to deal with the problem of selecting the optimal propellers. To do this, I even had to learn how to build diagrams on which the external and screw (throttle) characteristics of the motor are plotted.

The external speed characteristic is the dependence of the power of a fully loaded motor with an open throttle valve on the frequency of rotation. This is a property of the engine itself, such a characteristic can be taken from its technical data. True, Chinese manufacturers do not publish them, probably believing that consumers do not need such information. But you can always find the data of their Japanese prototypes.

The screw characteristic is the dependence of the power required to rotate the propeller on the engine speed (not the propeller!). It corresponds to the power of the internal combustion engine with the throttle closed to obtain the corresponding speed. This characteristic is a property of the propeller and, as the theory teaches, it is a cubic parabola.

The point of intersection of the external and propeller characteristics corresponds to the maximum power of the engine with this propeller. In the optimal case, it is at the top of the external characteristic. Then the propeller allows full use of engine power. If the screw characteristic crosses the outer one before reaching the maximum power, then the screw is considered hydrodynamically “heavy”. and the motor will not develop revolutions corresponding to this power. It is even worse when the screw is too “light”: the engine speed exceeds the maximum power, which is dangerous for the engine, leading to a sharp reduction in its resource.

From this follows a simple method for constructing helical characteristics. Let's pre-shake. that the creator of the motor picked up the screw for it correctly, and the characteristics intersect approximately at the point of maximum power. For example, for Salyut, this is 1.8 hp. at 5000 rpm. This point is sufficient for constructing a cubic parabop corresponding to the approximate helical characteristic of a standard screw. This is exactly how the diagrams of the external and screw characteristics of my "hybrid" outboard motors based on the transmission from "Salyut" with trimmer heads are built.

It can be seen from them that the "Salyutov" screws are fully consistent with the external characteristics of two-stroke trimmer motors. The real engine power in this case corresponds to 1.5-2 hp. with a working volume of 43 - 52 cm3 and 2.5 - 3 hp at 63 - 72 cm3. The use of more “heavy” screws, the characteristic of which will pass to the left, will not lead to anything good - it will only lead to slipping of the clutch.

TWO OR FOUR?

The diagram also shows the external speed characteristics of four-stroke trim motors. This is a new and not yet very numerous class of engines. They compare favorably with the "two-stroke" significantly lower, by about one and a half times, specific fuel consumption, less noise and cleaner exhaust. At the same time, they, unfortunately, have less power, develop lower speeds and are noticeably more expensive. They are lubricated by spraying engine oil poured into the crankcase. Only a small part of four-stroke trimmer internal combustion engines has a lubrication system that allows them to work in any position - this is the so-called "360 °" class. These include the Japanese Honda M4 series - the GX25 (25 cm3, 1 hp, 7000 rpm) and GX35 (35 cm3, 1.35 hp, 7000 rpm) models, as well as the Chinese Zongshen S35 (31 cm3. 0.9 p.s., 6000 rpm) and S40 (35 cm3, 1.2 p.s., 6500 rpm). All of them are equipped with a centrifugal clutch of the same design (GX25 - 54 mm in diameter, the rest - 78 mm). It's a pity, but more powerful "four-stroke" trimmers are not yet available.

As an experiment, I made an attempt to install a Zongshen S35 four-stroke head on the same folding “leg” from Sputnik. This requires only the correct selection of the propeller. Theoretically, with a constant blade cross-section along the radius, the power expended on rotating the propeller is proportional to the fourth power of its diameter. Accordingly, with a threefold decrease in power (from 3 hp to 1 hp), the screw diameter should be reduced by about 1.3 times, that is, from 158 mm to 120 mm. machine at the end of last season Sea trials have not yet been carried out, but their results are quite predictable. In displacement mode, the speed of the vessel is approximately proportional to the cube of the power of the power plant. Thus, when the power is reduced by a factor of three, it should decrease by a factor of 1.44, that is, from 8-10 to 5-7 km/h.

But noise will be significantly reduced, and it will be possible to abandon the headphones. By the way, this motor has already been tested at the stand, including when working “upside down”.

Interestingly, the very next year after the first tests of my homemade product, a fairly large number of models of Chinese inexpensive outboard motors of a similar design appeared on sale. Truly, good ideas are in the air! Of course, they do not have a folding “leg”, only “superpowers” ​​could afford this. And, jokes aside, they have one serious common flaw. All of them use the smallest of the mass-produced propellers today - from a two-horse Yamaha with a diameter of 178 mm and a pitch of 102 mm. However, for high-speed trimmer engines, even it is too “heavy”! Therefore, almost all users complain about overheating and rapid clutch wear. For the normal operation of such a motor, it is useful to reduce the "Yamahovsky" screw in diameter to 150 - 160 mm (the exact size is selected individually, as it depends not only on the motor head, but also on the features of the boat).

For clarity, all the characteristics of the considered motors, including the original Salyut, as well as some of those available on the market, are summarized in a table. The power of the engines is indicated close to the real one, taken from their external speed characteristics, and not from the accompanying papers. For the Chinese, this is important.

In conclusion, we can say that if you have an old Salyut with a faulty or worn out engine, do not rush to drag it to a landfill! With a simple refinement, you can get a more powerful and at the same time very light PLA with a modern motor head. This is especially true of the Sputnik and Sapyut-ES versions with folding legs. It's just stupid to sell them for scrap!

Similar Chinese-made motors are also a good purchase for their money, although they require fine-tuning of propellers. Their common disadvantages are: high noise and lack of transmission of rotation to the propeller at low speeds. They are easy to launch in any position, even without water, and can be successfully used as a spare “roller” on a medium-sized boat, but are practically unsuitable for trolling. However, as a motor for an amateur fisherman, another class of “hybrids” has no equal - home-made products built on the basis of four-stroke low-speed engines with vertical shafts, the so-called “lawn mowers”. I will talk about them in detail in the second part of this article.

Grigory DYAKONOV