How to Make a Trimmer Motor

Many people are wondering if it is possible to convert a rubber boat into a motor boat. To do this, mount the outboard motor from the trimmer on it.

How to Make a Trimmer Motor

Benefits of Using a Trimmer

Consider the advantages of using a trimmer:

  1. Do not have to buy an expensive outboard motor.
  2. An ICE made from a trimmer spends less gasoline than an outboard engine.
  3. The engine from the brushcutter is more compact than the factory engine for the boat.
  4. The engine of the brushcutter has high strength, tight housing, the presence of an integrated tank.
  5. It has all the nodes that are needed to control a homemade motor: starter, gas lever, rod, shaft, fuel tank.

Principle of operation

The motor for the boat from the trimmer has a higher speed of rotation of the blades, which allows you to move faster along the river. When the mower is working while mowing the lawns, its blades are turned in the opposite direction. In the manufacture of a motor for a boat, the engine blades are turned over. Then the engine will work to push the boat. The higher the blades are located to the surface of the water, the faster the speed of revolutions and the higher the speed of the boat.

Ready set of nozzles

Now they sell special nozzles for remaking the trimmer into an outboard motor. Such a prefix includes everything necessary for attaching a mower to the motor. The control handle and the switch button are mounted to the rod. The gas handle is made with the ability to switch speeds and is equipped with a ratchet, which secures the required position.

DIY boat motor

You can make a homemade outboard motor from a trimmer. First you need to prepare materials and tools:

  • 3 hp trimmer;
  • 2 mm thick steel sheet for screw;
  • Welding machine;
  • Fastenings;
  • A clamp for installing the engine on board the boat;
  • Angle Grinder;
  • Drill.

Before work, you need to create drawings indicating all sizes necessary for the operation of parts and assemblies, as well as the layout and installation procedure.

It is necessary to find out the size of the screw, which depends on the power and mass of the boat with the load. It should be borne in mind that a 3×10 cm propeller mounted on the internal combustion engine can carry a boat with passengers with a total weight of up to 120 kg.

Stages of manufacturing a motor from a mower:

  1. To make a motor for a boat, you first need to redo the bent shaft.
  2. Then make a screw.
  3. Replace plastic engine cover with switch.
  4. Attach the shaft to the engine from the mower.

Alteration of a bent shaft

First you need to redo the curved shaft. To do this, take a nut 2 cm high in the form of a cylinder with a thread inside. The unscrewed nuts and bolts must be kept, as they have non-standard threads. Then remake the bar with a rigid shaft. The flexible shaft is pulled out of the rod by removing the nut.

The end of the rod has no bearings, they are replaced by a sleeve, so it needs to be cut. Remove the tread. Since the metal pipe is bent, it is difficult to level it, so it will not be used. Instead, you should choose a dural pipe of the same diameter, or smaller than the diameter of the sleeve.

A bronze bushing is installed in the pipe. To do this, slightly bore the pipe. Then, gently press the sleeve over the groove with a hammer. It is not recommended that efforts be made so that the sleeve does not deteriorate. The tread is cut to the desired diameter and put into the bar. If the tube has a large diameter and it is difficult to put it in the hole in the head of the engine, then grind it to the required size.

Instead of a flexible shaft, take a steel bar and connect it to the motor shaft. Then screw on the shaft and fasten with a nut. Then it is necessary to fix the rod with the internal shaft to the engine using adapters. They need to be done in a turning workshop. Different mower models may have features to consider.

Using gear from angle grinder

To create an engine for a boat on the basis of a mowing machine, a reducer from an angle grinder is often used. It needs to be finalized. The shaft with the gear must be replaced with a longer one, which will correspond to the rod. The end of the shaft is carried out by analogy with the extracted short shaft so that the same bearings can be used.

In places of installation of the bearing, an oil seal is mounted, which will protect the angular gear from water ingress. The gear housing is twisted using sealant. Grease is poured into the gearbox to cover the gears.

Screw making

To create a screw you need a duralumin strip 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 inclination of the propeller blades must be adjusted with pliers. Before this, annealing of duralumin is performed. You can make screws with 2 or 3 blades, of various sizes. The dimensions of the propeller should be selected individually.


Sergey Petrovich, 58 years old, fisherman, Saratov.

Made a motor for a boat from a mower. Noisy slightly, the muffler removes the upper frequencies. I’ve been fishing on this boat for 2 years. The motor works reliably, without interference. I have never done a repair. Satisfied with homemade.

Mikhail, 40 years old, engineer, Tyumen.

Made a boat motor from a lawn mower. I made the design exactly according to the drawings. Installed a new speed switch, made a stainless steel drive, used plain bearings. The device turned out to be quite durable. Installed on a rubber boat. Works great. It is not difficult to make such a design yourself. And this gives great savings, since the factory motor is expensive.

Valentine, 43 years old, fisherman, Engels.

Grigory Ivanovich, 49 years old, carpenter, Petrozavodsk.

In summer, we always relax in the country and fish in a nearby river. Last year I put a motor from a brushcutter on the boat. I had to tinker when disassembling and redoing the structure. But everything turned out fine. The motor works properly and is no worse than an expensive finished engine. True, there is excess noise, but we are already used to it.