Do-it-yourself water cannon for a boat with your own hands: drawing, instruction

Creating a high - quality water-jet engine is associated with a number of research and design works. However, creating an elementary water cannon for a boat with your own hands will not be a problem. Consider the features and types of such motors.

Design Features

The main elements of a home-made unit include an internal combustion engine and a screw, as in factory models. The propeller in this case is located inside the pipe placed along the body of the floating means. A water conduit is not just a pipe, but a unit, which includes the following parts:

1. A water intake located at the front and used to supply water to the screw.
2. Also, the design of a water cannon for a boat, created with his own hands, includes a rectifying device. Its purpose is to transform a swirling water stream into a linear action.
3. The nozzle block, which closes the pipe, serves to eject fluid outward.
4. Steering gear reversible type. It allows you to change direction and reverse.

Screw types

There are several types of impellers with blades, which are also called impellers. Among them:

• Axial modifications. They are the easiest to manufacture, but give a low efficiency and work effectively only at low speeds due to high cavitation.
• Diagonal axial variations. They are well aggregated with power plants of medium speed and have a higher efficiency than the previous elements.
• Diagonal and screw type screws. They are more difficult to manufacture, however, they are varieties with the highest efficiency and can interact with motors at high speeds.

It is worth noting that in the manufacture of a water cannon do-it-yourself screws are especially difficult in terms of production. For this, a precision casting method with further grinding is used. Experts do not recommend the use of impellers, the blades of which are welded to the hub, since they often have an imbalance, which leads to their deformation when operating at high speeds.

Advantages and disadvantages

A homemade boat water cannon gives the owner of a boat a number of advantages, namely:

• Security and camouflage of the screw in a special pipe, which prevents the propeller from contacting with algae, increasing the maneuverability of the swimming means.
• Screw impacts to the bottom are excluded. This allows you to navigate in shallow water bodies and close to the coast.
• DIY water cannons for boats of this type do not pose a threat to bathers and fish.
• Unlike conventional rowing counterparts, modern water-jet structures are reliably protected from the negative effects of cavitation.

There were also minuses. These include the following aspects:

• With the same power of the power unit, the craft will move more slowly.
• The quality of handling suffers.
• The mass of the boat increases due to the additional weight of the water entering the water cannon.

How does the device work?

The unit in question ejects water at high speed, creating a jet propulsion, leading to the movement of the swimming means. If we consider this process in detail, we can note the following points:

1. The liquid is supplied to the water intake of a water cannon for a boat, made in advance by yourself. It is equipped with a special grid that eliminates garbage and algae. When creating a water intake, pay attention to the possibility of a laminar flow of water in it, since the additional turbulence and turbulence at the screw significantly worsen the characteristics of the motor.
2. In the next stage, the impeller forces the water back. It enters the narrowing chamber, so that its speed increases.
3. The straightening device further increases the speed by transforming the swirling motion into a rectilinear position. The blades of this apparatus are shaped to provide a minimum resistance to moving fluid. Manufacturers apply a variety of straightener configurations. One of the most popular options is the preloading of the scapular type, which guarantees the use of this element also as a nozzle.
4. At the final stage, the flow through the nozzle is converted with increasing speed.
5. To give optimal performance to the fixture, it is important to fit the nozzle portion in the correct profile.

DIY homemade water cannon for a boat, created on the basis of a centrifugal pump

Consider a design based on a Pacer Pumps 200GPM. Its body is made of durable plastic, weight is 18 kg. The pumping force is created thanks to the Intek power unit, with a capacity of five horsepower. The device is equipped with two-inch suction and discharge nozzles, the pressure force is about 35 meters.

The pump is placed on the boat, and then connected to a suitable pipe made of PVC material. It is discharged through an opening in the nose compartment of the bottom into the water. Additionally, the design is equipped with a strainer and performs the function of a water intake.

By means of a threaded fastening, a high-pressure fitting with an outlet with a diameter of 24 mm is screwed onto the nozzle. You can take a modification of vinyl, which is available at specialized stores. A PVC pipe will also act as a nozzle part. The fitting with the nozzle is connected via a rubber hose. Do-it-yourself water cannons for boats of this type have a jet thrust value that directly depends on the total length of the suction and discharge lines.

Exploitation

Given that the hydraulic force increases with decreasing pipe size, it makes sense to install the pump as close to the stern as possible. This will make it possible to optimize the length of the nozzle and increase the speed of the fluid in the line.

The engine type considered above has been tested on a 3500 mm long swimming craft with a suction pipe of 3000 mm. In such conditions, a water cannon on a PVC boat, created with his own hands, developed about 20 meters of a water column (about two atmospheres). This allowed to reach speeds of up to 8 km / h. When testing this kind of motors should be prepared for trouble. The fact is that the pressure fitting can unscrew freely under the flow of water. Additional glue treatment does not give the desired result. It is recommended to use additional fastening or flanges.

How to make a water cannon for a boat with your own hands on the basis of a boat engine?

As prototypes, you can use the units "Veterok 12", "Moscow", "Arrow", SM and others, suitable in power and size. It is permissible to place the water conduit inside or outside the swimming facility. The first option is more popular, because when placed externally, the hydrodynamic resistance increases. Water conduit elements are made of pipes and stainless steel sheets of suitable thickness.

First you need to create a drawing of a water cannon for a boat with your own hands, which will allow you to calculate the position and connection of all used parts. Billets of the desired configuration are made using a manual mandrel or a bending roller machine. The blades of the screw are also cut from a similar material. Then they must be profiled and welded to the hub. At the project stage, the drainage model can be made from papier-mâché. After cutting it in half, you get a pattern for the final harvest. Torque from the motor will be implemented through a standard gearbox. It is mounted on the main deadwood using a special flange.

Finally

Above were considered options for creating a water cannon for a boat with your own hands. How to make drawings correctly? Firstly, it will be necessary to take into account the dimensions and technical parameters of the swimming means. Secondly, you need to choose the right motor, calculate the length of the conduit. If there is no experience in such a matter, it is better to consult a specialist. This will allow you to work as efficiently as possible without being distracted by multiple alterations.