How to make a lawnmower into a boat motor

How to make a lawn mower into a boat motor

To move a motorboat, the installation of a lightweight outboard motor is often carried out. It is worth considering that such a mechanism is quite expensive and difficult to service.

Small boats are often equipped with motor trimmers. To date, they are very popular, to equip is the purchase of a special attachment. Let’s look at its features in more detail.

What is the nozzle for converting a grass trimmer into a boat motor?

Motors for light boats are often made of grass trimmer.

The basic ones are as follows:

• A clamp for the installation of a homemade structure with a trimmer on the prepared transom of the boat is very widespread. This option is considered more affordable, but is characterized by increased efficiency in the application of. The special design allows you to use the device as a propeller. While performing the usual function of a motor, the mechanism has a small size, easy to install and remove, which determines a very wide distribution.
• Propeller. This version is a little more complicated than the previous one, but there are ready-made mechanisms on sale, which are characterized by increased efficiency in the application. It is not recommended to carry out the most powerful version of the design, as due to the resulting traction the lightweight PVC boat can simply flip over. Often includes a special drive, made by using corrosion-resistant steel, as well as some adapters that make the grass trimmer almost universal boat motor.
• Another common option let’s call the conversion of a standard mower into a motor used to create traction. In this case we recommend to give preference to common trimmers, which require petrol to work. The relatively low weight of 4.5 kg is a significant advantage of this version.

Note! When choosing, you should consider the principle of operation of the design. The wrong grass trimmer will not be able to serve for a long period.

Principle of operation

When considering a grass trimmer, attention should be paid to the fact that such a mechanism provides a high rotation speed of the blades. This makes it possible to move the boat through the water at high speed.

The following points can be attributed to the peculiarities of the principle of operation:

• blades turned outward.
• The motor installed in the upper part transmits the rotation to the blades.
• To increase reliability, the shaft that connects the motor to the blades is located in a protective tube.

Note! The higher the grass trimmer is located, the higher the speed developed. The main disadvantage of such a motor can be called a strong noise at the time of operation. This factor is very important at the time of fishing, as the noise can scare away all the prey.

Advantages of using a grass trimmer

The grass trimmer has quite a few advantages that determine its distribution.

Let’s name the main ones as follows:

• Relatively low cost.
• Easy assembly and disassembly.
• Low weight.
• High speed achieved when driving.
• High power rating, often excessive.
• Economical.
• Initially there is a gas handle and starter.
• There is a special foot that allows you to adjust the power of the device.

These and many other qualities determine quite a wide distribution of trimmers in recent years.

What is the attachment for converting grass trimmer into a boat motor?

Motors for light boats are often made of grass trimmer.

The main ones can be called the following:

• A clamp for installing a homemade structure with a trimmer on the prepared transom of the boat is very widespread. This option is considered more affordable, but is characterized by an increased efficiency in the application. The special design allows the use of the device as a propeller. With the usual motor function the mechanism is small and easy to fit and remove, which makes it very popular.
• Propeller. This version is a little more complicated than the previous one, but there are ready-made mechanisms on sale, which are characterized by increased efficiency in application. It is not recommended to carry out the most powerful version, because of the resulting thrust a lightweight PVC boat can simply tip over. Often includes a special drive, made by using corrosion-resistant steel, as well as some adapters, which make the grass trimmer almost universal boat motor.
• Another common option let’s call the remaking of a standard mower into a motor used to create traction. In this case, it is recommended to give preference to common trimmers, which require gasoline to work. Relatively low weight of 4.5 kg is a significant advantage of this design.

Note! When choosing, one should take into account the principle of operation of the structure. The wrong grass trimmer will not last for a long period of time.

Operating principle

When considering a grass trimmer, attention should be paid to the fact that such a mechanism provides a high rotation speed of the blades. This ensures a high speed of moving the boat on the water.

The following points can be attributed to the peculiarities of the principle of operation:

• The blades are turned outward.
• The motor installed in the upper part transmits the rotation to the blades.
• To increase reliability, the shaft, which connects the motor to the blades, is located in a protective tube.

Note! The higher is the grass trimmer, the higher is the speed developed. The main disadvantage of such a motor can be called a strong noise at the time of operation. This factor is very important at the time of fishing, because the noise can scare away all the prey.

Advantages of using a grass trimmer

The grass trimmer has quite a few advantages, which determine its distribution.

Let’s name the main ones as follows:

• Relatively low cost.
• Easy mounting and dismounting.
• Low weight.
• High speed achieved when moving.
• High power factor, often excessive.
• Economical.
• Initially there is a gas handle and starter.
• There is a special foot that allows you to adjust the power of the device.

These and many other qualities determine a fairly wide distribution of trimmers in recent years.

Model of a chainsaw

It is possible to assemble the model from a chainsaw, if a ready-made deadwood is available. Also, the model will require a good stand. It is quite difficult to produce it yourself from a pipe. Screws are used most often of a small size. However, in this case, much depends on the power of the chainsaw. The clamp is fixed directly behind the starter. In order to protect the device from water, a cover is used.

A long rod is used to fix the prop. It should be soldered in a vertical position. Self-made boat motors from a chainsaw with water pumps are rare these days. It is also important to note that the clamp must be fixed together with metal corners. Some use screws or clamps for this.

Operating principle

Motor for the 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 petrol mower works when mowing lawns, its blades are reversed. When making a motor for a boat, the motor blades are inverted. Then the engine will work to push the boat. The higher the blades are to the water surface, the faster the rpm and the higher the boat speed.

And what a hose on the exhaust.what kind of material?

That motor is long gone, and the hose is metal, some kind of corrugated

I must have missed it, when I was making one, the weed trimmer 5.4hp for a one man boat, it was something else. Even the propeller blade flew off during the test, it was scary as hell.

Well done, but I see you have a hard welded leg mount, but it should tip over, like on the PLM.

There was a tipping of the whole motor with the transom, but that motor and the boat are long gone. But the record remains here)

Original! A beginner’s song! Even if it is loud

how I sealed the gearbox? There’s a hell of a lot of holes for purging, all of them will blow water into the shaft bearing area

There’s grease stuffed in there and that’s it, the gearbox has wintered well, checked the other day, everything spins and doesn’t whistle.

The stern tube goes straight to the shaft bearing? I understand it prevents water from getting in that way. I have a gearbox from a 230 angle grinder and there’s a bearing just in tandem with the water will grind (the upper primary shaft)

Ready to use nozzle kit

Now they sell special attachments for converting the grass trimmer into a boat motor. This attachment includes everything you need to attach it to the gasoline mower motor. The control handle and the on/off button are mounted on the shaft. The gas 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 unit on a boat. The grass trimmer attachment is easy to assemble, it has a simple design. To assemble it you need to attach the throttle cable to the engine and then fix the muffler cable. The nozzle costs about 5 thousand in a specialized store. rubles.

Motor for a boat with their own hands

You can make a homemade boat motor from a grass trimmer. First you should prepare the materials and tools:

• Grass trimmer with a capacity of 3 liters.с.;
• 2 mm thick steel plate for the propeller;
• welding machine;
• fasteners;
• a clamp to install the motor on board the boat;
• angle grinder;
• drill.

Before the work, you need to create drawings showing all the dimensions, necessary parts and assemblies for the work, 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 should be borne in mind that a propeller with dimensions 3×10 cm, mounted on the engine, can carry a boat with passengers with a total weight of up to 120 kg.

Stages of work to make a motor from a gasoline mower:

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

Rebuilding a bent shaft

First you need to redo the bent shaft. To do this take a 2cm high cylinder shaped nut with a groove on the inside. Retain the nuts and bolts that have been unscrewed because their threads are not standardized. Then rework the rod with a rigid shaft. Pull the flexible shaft out of the rod by removing the nut.

The end of the rod has no bearings, the sleeve replaces them, so it must be cut out. Remove the tread. Since the metal pipe is bent, it is difficult to straighten it, so it will not be used. Instead you need to find a dural tube of the same diameter, or smaller than the diameter of the sleeve.

Install the bronze sleeve in the tube. To do this you need to slightly bore the tube. The bushing should then be carefully pressed into the groove using a hammer. Do not force the bushing so that it does not deteriorate. Cut tread to desired diameter and install in boom. 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 necessary size.

Instead of a flexible shaft, take a steel bar and connect it to the motor shaft. Then a screw is screwed onto the shaft and secured with a nut. Then you must fix the rod with the inner shaft to the motor using adapters. These must be made in a lathe workshop. Different mower models may have peculiarities that must be taken into account.

Using the gearbox from an angle grinder

To create a boat engine on the basis of a haymaker often use the reducer from an angle grinder. It needs to be reworked. The shaft with the pinion must be replaced with a longer one, which will fit the rod. The end of the shaft is made by analogy with the extracted short shaft in order to be able to apply the same bearings.

In the places where the bearing is installed, mount the gasket, which will protect the bevel gear from water ingress. The gearbox housing is twisted with sealant. Pour grease into the gearbox to cover the gears.

Propeller making

To make the propeller you need a strip of dural, 100 mm long and 30 mm wide. If you put the screw on the table, then from it to the blade should be 10 mm. The angle of the propeller blades should be adjusted with a pair of pliers. Before this, anneal the dural. You can make screws with 2 or 3 blades, different sizes. The dimensions of the propeller should be selected individually.

A motor for a boat with his own hands

You can make a homemade boat motor from a grass trimmer. First you should prepare the materials and tools:

• Grass trimmer with a capacity of 3 liters.с.;
• 2 mm thick steel plate for the propeller
• welding machine;
• fasteners;
• a screw clamp to mount the engine on board the boat;
• angle grinder;
• drill.

Before the work, you must create drawings showing all the dimensions, parts and assemblies required for the work, as well as the scheme and order of installation.

You need to find out the size of the propeller, which depends on the power and weight of the boat with cargo. Keep in mind that the propeller size 3×10 cm, mounted on the engine can carry a boat with passengers with a total weight of up to 120 kg.

Stages of work to make a motor from a gasoline mower:

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

Redoing the Bent Shaft

First you need to rebuild the bent shaft. To do this, you need to take a nut 2 cm high in the form of a cylinder with a notch inside. Unscrewed nuts and bolts must be saved, because they have a non-standard thread. Then remake the boom with a rigid shaft. Remove the flexible shaft from the rod by removing the nut.

The end of the boom 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. Instead of it, you should pick up a dural tube of the same diameter or smaller than the diameter of the hub.

A bronze sleeve is placed in the tube. To do this you have to bore the tube slightly. Then carefully press the bushing into the groove with a hammer. It is not advisable to apply force so that the sleeve does not deteriorate. The tread is cut to the desired diameter and placed in the rod. If the tube has a large diameter and it is difficult to put it in the hole of the ICE head, 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 it on the shaft and secure it with a nut. Then it is necessary to fix the rod with the inner shaft to the engine by means of adapters. They must be made in a lathe workshop. Different mower models may have peculiarities that must be taken into account.

Using the gearbox from an angle grinder

To create a boat engine on the basis of a haymaker often use the gearbox from an angle grinder. It needs to be refined. The shaft with the pinion must be replaced with a longer one, which will fit the boom. The shaft end is designed in the same way as the removed short shaft, so that the same bearings can be used.

At the bearing locations, mount a gasket that will protect the bevel gear from water. The gear case should be twisted with sealant. Pour grease into the gearbox to cover the gears.

Making the screw

To make the propeller you need a dural strip 100 mm long and 30 mm wide. If you put the propeller on the table, there should be 10 mm from the propeller to the blade. The angle of the propeller blades must be adjusted with the pliers. Beforehand, the dural is annealed. It is possible to make screws with 2 or 3 blades, different sizes. Propeller dimensions must be selected individually.

Features of the homemade engine

When re-equipping the motor, you should take into account that they were developed for different functions. trimmer for grass functions at high revolutions and a small torque, and a boat motor must do the opposite. Therefore, redesigning the device requires special tools and even a drawing.

Engine from a trimmer for grass is more convenient and easier to construct, since it has a number of necessary component mechanisms:

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

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

a grass trimmer operates at high revolutions and low torque, and a boat motor must do the opposite

What can be made

There are several possible refinements to the grass trimmer under the motor for the swimmer.

Make it a rule that on every fishing trip, the first thing to do is to.

A very simple method, but one that requires an additional financial outlay.

It will be necessary to purchase such parts:

• A clamp to secure the unit to the boat transom.
• Propeller. You can buy a ready-made kit online, as stores such products can not be. The set includes a special drive made of stainless steel, as well as universal adapters for flexible shaft trimmer for the grass, which allows not to bother with the fact that they fit your model of lawnmower or not.

The drawing of the attachment to the trimmer is in the manual. For installation, you will need about half an hour.

For modification we will need an angle reducer from an angle grinder, a screw, which can be cut from a sheet of stainless steel, as well as seals and bearings for fixing. This method allows you to get maximum revolutions despite the small pitch of the propeller. In the field, the device requires additional adjustment, which is carried out with a pair 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 capacity of 25 cm3. A device that weighs 4.5 kg and has a power of 700 W, equipped with a bent leg. Grass trimmer with such power allows you to move the boat at a speed of about 5-7 km/h.

For modification you will 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

What will be needed

You will need materials as well as tools to make it:

• weed trimmer.
• Duralumin with a thickness of 2 mm. It is needed for the propeller.
• Screw clamps or any other device for attaching the unit to the boat.
• Welding machine.
• Fixing elements.
• Additional tools for work.

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

Instructions for making one

To make a boat engine out of a regular grass trimmer you will need to do the following:

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

Rebuild a bent shaft. To do this, you need to take out the regular nut, which is located in the spool with the line. It looks like a small tube that is 2 cm long and has internal threads. It can be split into two complete nuts. Tip! Never throw away or lose the nuts, because the companies developers use their own type of thread, which is not metric or inch. Next, you must remove the plastic overlay that is on the gas button. At the end of the bent rod there are no roller bearings, instead there is an ordinary sleeve made of bronze, also known as a plain bearing, it must be removed. To do this it is necessary to carefully cut it out by first unscrewing the nut and removing the metal and stern shaft from the tube. 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, as it will not be aligned. Instead of it we use a duralumin tube with the appropriate diameter. Mount the bronze sleeve in the duralumin tube and carefully press it along the chamfer with a hammer. Then take the plastic protector, trim it a little in diameter and mount it tightly in the tube. 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 turn it to the right size. If necessary you can build a longer shaft using a tube of desired length and install a steel bar instead of a flexible shaft of desired length.

• Creation of the propeller. For it we use a duralumin strip with the dimensions 10×3 cm and process it according to the drawing, then carefully sharpen the edges. The pitch of the propeller should be about 10 mm, so you should bend each blade up 1 cm. A nut is sufficient for mounting. A key will not be needed, in case the screw touches something, the motor will automatically stop. Adjusting it is very easy with a pair of pliers. If the rpm created by the propeller is low, you can shorten the blades a bit. Tip! Create a special ring attachment so that the propeller does not accidentally catch the cylinders.
• throttle gauge. You can mount a normal bicycle derailleur to the body instead of the original plastic plate. If you wish, you can change the course of the exhaust gases and direct them toward the propeller.
• Shaft fasteners for the motor. From ordinary laminated plywood, you can create two pads, which are needed to attach the motor to the head, and using four screws to properly clamp the shaft. If necessary, the shaft can be disconnected at the time of transport of the unit.

Materials and tools required

To convert the grass trimmer into a boat motor, you need to prepare the following materials:

• Lawn mower with a power of at least 2.2 kW (3 hp.с.);
• Sheet of stainless steel or dural 2 mm thick and with dimensions not less than 10×3 cm;
• steel rod length equal to the length of the straight part of the grass trimmer boom;

• Tapping tap for threading. Diameter must match the diameter of the metal rod;
• handbrake handle from a bicycle
• clamp for securing the grass trimmer to the stern of the boat.

You can use the housing of an old meat grinder as a mounting device. After sawing off the top of the meat grinder, you are left with a sturdy clamp, to which you can easily weld or screw the motor.

Of the tools you will need:

Tapping tap for threading on a steel rod

A welding machine will also come in handy. Most metal connections do not involve further disassembly, so it is faster and more reliable to tack the metal with welding than to drill and fit holes for screw connections.

Advantages of using a grass trimmer

First of all, it is worth considering the main advantages of using a grass trimmer to make a boat motor:

• The cost of grass trimmer is much lower than the cost of a complete motor for the boat;
• Fuel consumption is very economical;
• reliability in operation;
• small weight, which is very important when using a grass trimmer on rubber boats;
• built-in translucent fuel tank, through the walls of which the gasoline level is clearly visible;
• A sufficiently tight construction;
• A rigid shaft is installed in the boom;
• To control the machine there are ready-made elements (starter and gas).

All these qualities of the device put it in the first place, if you take into account other options for remodeling. So, so that the grass trimmer (requires power from 0.7 kW) turned into a full-fledged boat motor, it is necessary to buy a special set of attachments or make them with your own hands.

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

To build a boat motor from a lawnmower, a tool with a straight rod will do. If the grass trimmer boom is curved, you will have to work on its improvement.

Remodeling takes place according to the following algorithm:

First, remove the staff nut (in the drawing below is marked with the number 2). Do not throw it away or lose it, because it is impossible to replace the factory parts with ordinary nuts.

If it is not possible to purchase a ready-made set for the remodel mentioned earlier, the adjustment handle can be taken from a sport bike handle.

You can also make the propeller yourself from a piece of duralumin using the drawing below:

Pitch is the distance from the blade to the horizontal surface. The angle of inclination is adjusted by the pliers. Preheat the workpiece.

To refuel the motor from the grass trimmer on the boat, use only high-quality fuel and lubricants. Dilute petrol with oil in the appropriate proportion. Do not expose the engine to high loads for the first 10 km. this will be the break-in period. Depending on the capacity of the engine, the boat with such a motor can develop a speed of 5 to 8 km / h.

Below is a video that demonstrates the work of such a unit:

Making an attachment for mounting the motor on the boat

To install a homemade boat motor from a lawnmower, you can use a ready-made clamp. But if you’ve got an old meat grinder in the garage, it shouldn’t be too difficult to make an engine mount that can be used to mount it to the transom:

• Use an angle grinder to cut the bottom of the blade and drill a hole with a diameter of 12 mm in the transverse plane of the body.
• The stud with a diameter of 12 mm and a length of 100 mm flatten one end and drill a hole with a diameter of 6 mm in the resulting plane.
• Insert into the resulting hole a bolt with a suitable cross-sectional diameter. The ring of the grass trimmer will be mounted on it, which was originally intended for fixing the belt.
• Now you can connect the homemade mount to the boat transom with a stud and a nut. Install the motor and secure it with the appropriate nut.

Making a fastener for mounting the motor on the ship

You can install a homemade boat motor from a lawnmower with a ready-made clamp. But if you have an old hand grinder in the garage, it shouldn’t be too hard to make an engine mount to mount it to the transom:

• Use an angle grinder to cut the bottom of the grinder and drill a 12 mm diameter hole in the transverse plane of the hull.
• At a stud with a cross section diameter of 12 mm and a length of 100 mm to flatten one end and drill in the resulting plane hole diameter of 6 mm.
• Insert the bolt with the appropriate diameter into the hole you’ve made. The grass trimmer ring will be mounted on it, originally intended for belt attachment.
• Now you can connect the fixture to the boat transom with a stud and a nut. Install the motor and secure it with the appropriate nut.

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

To assemble the motor from the grass trimmer on the boat, the manufacturer will need to prepare the following equipment and materials:

• household lawnmower;
• clamp. If it is not available, you can use any other mount to secure the motor to the boat;
• sheet of duralumin, which thickness should not be less than 2 mm;
• welding machine;
• a set of fasteners;
• a set of screwdrivers and a wrench.

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

it is necessary to remember that the lower power of used drive and boat weight is, the smaller blades should be. For example, for a boat with a maximum weight of 120 kg a propeller with blades 10×3 cm will do.

After preparing the equipment and a thorough study of the drawings, you can begin assembling the self-made.

The work algorithm should look as follows:

• First of all, the maker will need to finalize the bent shaft. First you need to dismantle the factory nut, placed in a reel with pre-wound fishing line. The nut itself is shaped like a small 2-centimeter tube with an internal thread. If necessary, it can be divided into 2 small complete nuts. When removing the fasteners you must be extremely careful not to lose them. If this happens, it is no longer possible to find another suitable fastener;
• After removing the nut you will need to remove the plastic cover located on the throttle button. There are no roller bearings on the end of the bent rod. They are replaced by an ordinary bronze sleeve, which is often called a plain bearing. It must be carefully removed. Before this, it is necessary to unscrew the nut, as well as to remove the stern and metal shafts from the tube;
• Then you need to proceed to knock out the plastic tread located on the flexible shaft. Afterwards you can throw the steel tube away, because you will not be able to straighten it out by improvised means. It can be replaced with a duralumin tube of the same diameter. You will need to install a bronze sleeve, which will need to be moved along the ledge with a hammer. Next, you need to take a pre-cut to the diameter of the plastic protector, and install it on the tube;
• The next step is to make a screw. For this you need to cut duralumin blades and sharpen their edges. After that, each blade will need to bend upwards by 1 cm, so that the propeller pitch is at least 10 cm. You can fasten the finished fixture with a nut;
• Next, you need to install a bicycle gear shifter on the brushcutter boat motor, which will replace the standard plastic overlay. After that, you will need to install a muffler, which will divert the engine exhaust away from the boat driver;
• To secure the boat motor from the lawnmower, you need to use two sheets of plywood. After that, it will be left to clamp the shaft, using 4 screws for this purpose. During the transportation of the boat motor from the grass trimmer, the shaft can be removed.

After the homemade nozzle will be ready, it will need to be run-in. To do this, you need to prepare a fuel mixture of fresh gasoline and motor oil in a ratio of 40:1. After that, you will need to pour the ready mixture into the regular tank of the boat engine, start it up, and let it work out 1 full tank of fuel at idle speed. After the run-in homemade boat motor from the trimmer for grass will be fully ready to work.