DIY. Trimmer As a Boat Engine.

The idea of ​​a light outboard motor for a small boat, including a rubber one, is interested in many fishers and not only. An engine that could become an alternative to an electric motor with heavy and not cheap batteries and a small power reserve plus the ability to recharge in nature is a dream for many. If you add a relatively low price and versatility, that is, the ability to use for other useful purposes. then the trimmer motor (mowers or lawn mowers. call it what you want). is not a bad option. And if you already have a trimmer, it would not be wrong to use it as an engine for a boat.
Why trim? Light, modern, “low-drinking”, with a built-in tank motor, with ready-made controls: throttle knob, starter. There is even a long “leg”. What else do you need?
But it is necessary to adapt this unit to the boat so that it performs the functions of a boat motor. And here there are various options.

The first, most straightforward, though not the cheapest. we buy the necessary parts.

  • Clamp for attaching a homemade outboard trimmer motor to boat transom

Although it is not necessary to buy ready-made, it is quite possible to make it yourself: a little imagination and straight arms.

  • Propeller screw.

It is a bit more complicated here, but not hopeless. In the first embodiment, buy a ready-made set. Yes, there are such kits for applying trimmer as a boat motor, which can be purchased in the store. The kit includes an adapter to the flexible trimmer shaft. Transitions can be universal, and it pleases. By the way, the clamp often also comes in the kit, so if you buy, you first need to clarify the composition of the package.
The attachment to the trimmer is explained in the instructions and takes no more than 30 minutes, with all the preparatory work.
That’s all. You can experience ready trimmer outboard motor and install on the boat.

Second option.  Improvements mowers for outboard motor.

We do as much as possible with our own hands. It is proposed to consider a specific example of the craftsman Vigovsky I.
Petrol trimmer Weedwacker. (you can use any other with similar characteristics)
Engine: two-stroke, of 25 cm3
Power: about 700 watts.
Weight: 4.5 kg.
With a bent leg.

Alterations trimmer were as follows:

Alteration of a bent shaft.
First of all, I removed a regular nut from the reel with a fishing line. It is a tube of length 20 mm. With internal thread. If you cut it, you get two 🙂
Important. Nuts should be protected, as tricky manufacturers invented their thread: not metric and not inch.
Then he removed and threw out the plastic cover with the gas key.
1. Cone gum (auto parts).
2. Nut (regular).
3. Screw.
4. Nut (regular).
5. Groove sleeve bushing.
6. Bronze bushing (standard).
7. Dural pipe of suitable diameter.
8. Deadwood Shaft.
9. Flexible shaft
10. Plastic flexible shaft protector.
At the end of the bent pipe, there are no roller bearings, and there is a usual bronze bushing (plain bearing). This sleeve should be carefully cut. To do this, remember to remove the flexible metal shaft from the pipe, unscrew the nut, and remove the stern shaft
After removing the bronze bushing, we knock out the plastic protector of the flexible shaft from the metal bent pipe and throw the pipe away because it is steel and all attempts to straighten it have nothing to do.
Instead of a standard pipe, I picked up a duralumin one with approximately the same internal diameter. A bronze bushing was pre-pierced into it (the tube had a slightly smaller inner diameter) and pressed it along the groove with a hammer, but gently and gently, so as not to damage the bronze bushing.
The plastic protector slightly trimmed in diameter and firmly inserted into the tube. If the outer diameter of the tube is large, and will not crawl into the mounting hole to the motor head, then it must be machined to size.
If you want, you can make the shaft longer than the standard flex. It is necessary to take the pipe of the desired length and install the steel bar of the desired length in place of the flexible shaft. So the shaft is ready.

Making a screw.

No need to adapt to the mower screw from “Salute” or, God forbid, from the “Whirlwind” they do not fit. You can do much easier.
Take a strip of 2 mm. dural size 100×30 mm. and we process according to the drawing. Edge sharping.
The pitch of the screw is about 10 mm., That is, if you put the plate on the table, then you need to bend the blade to a height of 10 mm., Then bend the second blade.
The screw is easy to adjust. If the rotations are not high, you can cut the blades or adjust the pitch of the screw, using a joint with preliminary annealing of duralumin.
Fasten the screw with the nut and hold it tightly — no need to key. If the screw touches anything, the motor stops.
Attention: you can and you need to make a ring nozzle, as you can accidentally screw the cylinders of the boat with a screw.

Gas Strip.

Native plastic lining on the pipe with the gas key was ruthlessly thrown out. Instead, I bought a bicycle gearshift and installed it on the body.
And one more thing: in the future, I plan to change the direction of exhaust gas emission towards the screw.

Fastening the shaft to the motor.

Made from 20 mm. Laminated plywood are two pads that are attached to the head of the motor and clamp the shaft with four screws. The shaft can be separated during transportation.

Results of operation:

The motor was operated for one season, that is, all summer on Saturdays-Sundays and one long hike for 25 days. During this time, 15 litres were burned. 92 gasoline.
Engine run-in should be made on a mixture of gasoline to oil 1:40 (as in the passport). For running, it is enough to burn one tank (0.5 litres). Then you can dilute the gasoline with oil in the ratio of 1: 100.
It is tested and does not affect the condition of the motor.
On one tank (0.5l.), In calm, you can drive about 10 km.

Speed ​​under the motor for the boat from the mower (measured by GPS):

The catamaran of the “Prostor” type weighing 120 kg., In calm, with one person on board. 7.9 km / h.
The catamaran of the “Expanse” type weighing 120 kg. with one person and junk on board catamaran “Albatross” with two people and trash, in tow. 5.6 km / h.
Use the trimmer not only for its intended purpose but also as an excellent alternative to the outboard engine.