Boat motor from brush cutter with his own hands

Features of the homemade engine

When retrofitting a motor, it’s worth considering that they were designed to perform different functions. A grass trimmer functions at high rpm and low torque, while a boat motor should do the opposite. Therefore, the redesign of the device requires special tools and even a drawing.

The grass trimmer engine is more convenient and easier to construct, as it has a number of necessary component mechanisms:

• A very economical engine;
• mounted unpainted fuel tank, allowing you to easily control the amount of fuel;
• the presence in the device of the starter and gas;
• boom, equipped with a rigid shaft.

It only remains to buy the missing parts or make them yourself and you can proceed to the manufacture of the motor for the boat.

The grass trimmer operates at high rpm and low torque, and the boat motor should do the opposite

What you can do

There are several possible ways of grass trimmer finalizing for a swimming motor.

Take it as a rule, in every fishing trip, the first thing to start.

A very simple way, but requires additional financial expenses.

It will be necessary to purchase such parts:

• Screw clamps for attaching the device to the boat transom.
• Propeller. You can buy a ready-made set through the Internet, since in stores such products may not be available. Included is a special drive, made of stainless steel, as well as universal adapters for flexible shaft trimmer for grass, which allows not to bother with the fact that they come to your model of lawnmower or not.

Tip:! Sometimes the kit may include a clamp, so before you buy it clarify what is included.

The drawing of the attachment to the trimmer is shown in the manual. It will take about half an hour to install.

For conversion we need an angle gearbox from an angle grinder, a screw, which can be cut from a sheet of stainless steel, as well as seals and bearings for the fasteners. This method allows you to get the maximum revolutions, despite the small pitch of the propeller. In the field, the device requires additional adjustment, which is done with the help of pliers.

This method is performed as much as possible with your own hands. Let’s consider it in more detail on the example of a lawnmower with a two-stroke motor with a volume of 25 cm3. The 700 watt, 4.5 kg device has a bent leg. Grass trimmer with this power allows you to move the boat at about 5-7 km/h.

For conversion you’ll need an angle gearbox from an angle grinder, a screw that can be cut from a sheet of stainless steel, as well as gaskets and bearings for fixing

What you need

Materials as well as tools will be needed to make it:

• Grass trimmer.
• Duralumin with a thickness of 2 mm. It is necessary for the screw.
• Clamp or any other device for attaching the device to the boat.
• Welding machine.
• Fasteners.
• Additional tools for the job.

All necessary elements can be bought or made by yourself. You may need the blueprint for designing a homemade propeller, but not for the drive. The size of the screw depends directly on the power of the drive as well as the weight of the swimmer. For example, a propeller with dimensions of 10×3 cm is able to move the vehicle weight of about 120 kg.

Instructions for making

To make a boat engine from an ordinary grass trimmer you will need to do the following steps:

Never throw away or lose the nuts, as the developer companies use their own type of thread, which is not metric or inch

To redo the bent shaft. To do this, you should remove the standard nut, which is located in the spool with a fishing line. It looks like a small tube that is 2 cm long and has internal threads. It can be divided into two complete nuts. Tip! Never discard or lose the nuts, as the developer companies use their own type of thread, which is not metric or inch. Next, you must remove the plastic cover, which is located on the gas button. There are no roller bearings on the end of the bent rod, instead there is a plain bronze sleeve, also known as a plain bearing, it must be removed. To do this you need to carefully cut it, first unscrewing the nut and removing from the tube metal and stern shaft. Once free of the bronze sleeve you can proceed to knock out the tread of the flexible shaft, which is made of plastic. Tip! The steel tube can be discarded, because it cannot be straightened. Instead we use a duralumin tube with the appropriate diameter. Mount the bronze sleeve in the duralumin tube and carefully press it on the chamfer with a hammer. Then we take a plastic protector, trim it a little in diameter and mount it tightly in the pipe. Tip! When the outer diameter of the tube is larger and does not fit into the mounting hole on the motor head, you will need to mill it to the right size. If necessary you can build a longer shaft using a tube of desired length, and install a steel rod instead of flexible shaft of desired length.

For running-in of the homemade engine we will need a tank of gasoline (0.5 l of fuel).) with oil in a 1:40 ratio. One tank of fuel can cover about 10 km of territory. The speed of the watercraft with such a motor is between 5.6 and 7.9 km/h depending on the load of the boat.

Grass trimmer motor: features

The idea, to use as a boat engine from something else, has occurred to more than one homemaker. As a result, the motor for the boat with their own hands learned to make a lawn mower, electric screwdriver, and, of course, lawn mower. Of course. because the cost of lawn mower compared to the motor is an order of magnitude less, and the drive power is quite acceptable.

Motor from a grass trimmer is the easiest to make, as the device has all the necessary mechanisms:

• Economical engine. especially if it is a four-stroke. In most cases, the two-stroke is used, of course, as the cost is lower;

The only difficulty in reinstalling the motor. different tasks for which the engines were designed. The drive on the gasoline mower works with high revolutions and low torque, while the boat drive should do the opposite. Therefore, to construct a boat motor from a trimmer for grass, you will need both tools and drawings. In the photo. an example of using a lawnmower as a drive.

What do they make homemade motors for boats?

Some products will be suitable, even defective, but on one condition that their motor works. Even if you buy a new gasoline mower or an electric screwdriver, it will be much cheaper than a new boat motor, the only thing left is to modify the product a little. The financial issue turns out to be the main one in solving this problem, otherwise every boat would have a motor.

• To make a boat motor with an electric motor, you will have to buy an electric screwdriver or an electric drill on rechargeable batteries. Perhaps someone has a ruined electric screwdriver or drill lying around in the shed or garage. an electric screwdriver is preferable, because its output speed is not as high.

• Naturally, those batteries that are installed on electric devices will not be enough power to move around the pond for a long time. In that case a 12 V car battery will do. Naturally, the devices must be purchased for the same operating voltage. 300 W of power is enough to move the boat with the load on the pond.
• It is also necessary to solve the problem of reducing the speed of the electric device. In this case, you will need a gearbox. This is especially true when using an electric drill.
• You will also have to make or buy a drive shaft and propeller. The advantage of an electric boat motor is that it is silent. In addition, the repair of such a motor is much cheaper than the repair of a classic boat motor.

• Gasoline motors are much more powerful, so they can significantly increase the catching area. They do not lose as much power as electric motors and the battery pack weighs a lot more and takes up more space. You can use power units from brush cutters, tillers, chainsaws, etc. д. The choice should be based on financial possibilities, the size of the boat, as well as what kind of device is available.

• Grass trimmers are most suitable for such purposes, as they require minimal modifications. It is enough to replace the device, where the line is attached and install a propeller, the motor is ready and can be used.
• Other power devices require more serious modifications, because a gearbox, shaft and propeller will be required. In addition, they need to be connected together.

Boat engine with brush cutter | boat engine at low price | XTRACUT brush cutter | weed cutter

Just a side note! Some anglers use a motor cultivator, removing the cutters and installing primitive propeller blades in their place.

In addition to making a motor, you should think about how to fix it on the boat. The thing is that not every boat has a transom and not every boat is adjusted to install a motor. It is especially difficult to install such a device on a rubber inflatable boat.

Advantages and peculiarities of converting grass trimmer into a boat motor

The use of a lawn mower available in the farm has a number of advantages. First, the boat owner will not overpay for a store-bought, expensive motor. Secondly, a motor for a boat from a brushcutter consumes much less fuel than a specialized boat engine. Third, the engine from the lawnmower has an order of magnitude less dimensions than a store-bought boat motor. There are a number of other factors that force fishermen to use a grass trimmer instead of a boat motor.

• high reliability of modern trimmer engines;
• complete tightness inside the body;
• The presence of all the necessary elements for controlling a homemade engine;
• built-in tank.

Thanks to all of these factors, the boat motor from a brushcutter is the most popular among enthusiasts.

In the process of recycling an engine from a lawnmower into a boat motor, it is extremely important to take into account that this power unit was produced for other purposes. Engines on trimmers work at low torques, but, at enough high revolutions. In the case of a specialized boat engine, everything is the opposite. In this connection, to remake motor from trimmer for grass need to prepare drawings, equipment and follow a certain order of action.

Despite some difficulties in the remaking, it is the trimmer that has all the details necessary for making a boat motor. a built-in starter and gas lever, a rod with a rigid shaft and a semi-transparent fuel tank.

A boat motor from a trimmer for grass: step by step instruction for remaking

Converting an ordinary boat, even a rubber one, into a motorboat is easy: you need to install a gasoline engine on it. Electric is not valued by our fishermen: heavy, low power reserve, and there is no way to recharge it during a long fishing trip. But the cost of even the easiest variant for a boat is rather high. 20-30 thousand. р.

How to make a boat motor with their own hands from a trimmer for grass?

To assemble a grass trimmer motor for a boat, the fabricator will need to prepare the following equipment and materials:

• household lawnmower;
• clamp. If it is not available, you can use any other attachment to securely fix the motor to the boat;
• sheet of duralumin, which must not be less than 2 mm thick;
• welder;
• set of fasteners;
• screwdriver and wrench set.

To assemble a homemade propeller, the manufacturer will need drawings. They must specify the exact dimensions of the blades and how they are fixed to the axle.

Working principle

Motor for a boat from a grass trimmer has a higher speed of rotation of the blades, which allows you to move faster on the river. When the lawn mower is running, its blades are reversed. When making a motor for a boat, the motor blades are flipped. Then the engine will work to push the boat. The higher to the surface of the water are the blades, the faster the speed of rotation and the higher the speed of the boat.

Motor for a boat with your own hands

You can perform a homemade boat motor from a grass trimmer. You should first prepare the materials and tools:

• Grass trimmer with a capacity of 3 liters.с.;
• 2 mm thick steel plate for the screw;
• Welding machine;
• fasteners;
• clamp for installing the motor on the side of the boat;
• angle grinder;
• drill.

Before the work, you need to create drawings with all the dimensions, necessary for the work of parts and components, as well as the scheme and order of installation.

You need to figure out the size of the propeller, which depends on the power and weight of the boat with the load. It is necessary to take into account that a propeller with dimensions 3×10 cm, installed on the engine, can carry a boat with passengers with a total weight of up to 120 kg.

Stages of work on making a motor from a gasoline mower:

• To make a motor for a boat, you must first redo the bent shaft.
• Then make a screw.
• Replace the plastic motor cover with the switch.
• Attach the shaft to the engine from the mower.

Rebuild the bent shaft

First the bent shaft must be reworked. Take a 2 cm high cylindrical nut with a thread on the inside. Unscrewed nuts and bolts must be kept because their threads are not standardized. Then redo the boom with the stiff shaft. Pull the flexible shaft out of the boom by removing the nut.

The end of the rod has no bearings, a bushing replaces them, so it must be cut out. Remove the tread. Since the metal tube is bent, it is difficult to align it, so it will not be used. In its place pick up a dural tube of the same diameter, or smaller than the diameter of the sleeve.

Place the bronze bushing into the tube. To do this you need to slightly counterbore the pipe. Then carefully press the bushing into the groove with a hammer. It is not recommended that you twist the battery to avoid damaging the battery sleeve. The tread is cut to the required diameter and put into the rod. If the tube has a large diameter and it is difficult to put it in the hole of the head of the engine, you should grind it to the required size.

Instead of a flexible shaft, take a steel bar and connect it to the motor shaft. Then screw a screw on the shaft and secure it with a nut. Then fix the rod with the inner shaft to the motor by means of adapters. These need to be made in a lathe workshop. Different models of mowers may have features that need to be taken into account.

Using the reducer from an angle grinder

To create a motor for a boat on the basis of a haymaker often use the reducer from an angle grinder. It needs to be refined. The shaft with the pinion should be replaced with a longer one that will fit the rod. The end of the shaft is made by analogy with the extracted short shaft so that the same bearings can be applied.

In the places where the bearing is installed, a gland is mounted, which will protect the angular gear from water ingress. The gear case is screwed together using sealant. Grease is poured into the gearbox to coat the gears.

Propeller fabrication

To make the screw you need a 100 mm long and 30 mm wide strip of duralumin. If you put the propeller on the table, then from it to the blade should be 10 mm. Adjust the angle of the propeller blades with the pliers. Before this, the dural is annealed. It is possible to make propellers with 2 or 3 blades, different sizes. Propeller size should be adjusted individually.

Ready set of nozzles

Now they sell special attachments for converting the grass trimmer into a boat motor. Such an attachment includes everything necessary for attaching to the motor gasoline mower. The control handle and the switch button are mounted on the propeller shaft. The throttle handle is made with the possibility of switching speeds and is equipped with a ratchet that fixes the desired position.

The kit includes a device for mounting the device on the boat. The grass trimmer head can be assembled easily, it has a simple design. To reassemble should connect the throttle cable to the motor, and then fix the cable muffler. It costs about 5,000 at a specialty store. rubles.