The bulk of the manufacturers of motors complements their own production screws. Such a solution seems appropriate, since the development of the rowing facility in accordance with the parameters of the engine makes it possible to convert power to a high, proportional speed of movement. However, it is often necessary to pick up the propeller screw separately. Let's try to sort out this issue.
Nowadays, rowing propellers made of plastic are extremely common on the market. Such options differ primarily in budget cost. It is obvious that the disadvantages here are strength, resistance to shock loads, as well as the duration of service.
More reliable in comparison with the previous version is the aluminum propeller screw. Such a solution is in demand because of its low cost. Among other things, the aluminum propeller does not lose blades when hitting the bottom. The latter simply bend without catastrophic consequences.
As for steel screws that have a stainless steel coating, this option is the most expensive, but it adds speed considerably. Since the steel is extremely durable, if the blades are inadvertently in contact with hard surfaces during movement, you can easily lose the gearbox of the boat engine. The latter circumstance is a minus of this decision.
To correctly select the effective propeller screw, it is worth understanding a few concepts:
- Screw diameter - defines the circle described when the blades move.
- Slippage is the difference between the actual progress of the boat and the pitch of the propeller. Arises due to runoff from the blades of water.
- The pitch is the distance that the swimmer will cover in one turn of the screw, not taking into account the effect of slipping.
- Disk ratio is the ratio of the area of a circle described by a screw to the area of its blades.
The most important quality, which determines how effective the propeller screw will be in operation, is the step indicator. Understand what kind of characteristic is possible by example. Thus, a step of 10 indicates the passage of the craft during one complete turn of the propeller a distance of about 0.3 m. By purchasing a propeller with a high step rate, the boat speed can be significantly increased, spending less time to overcome the required distances.
The circumference, which is described during the rotation, is reflected in the movement parameters. However, manufacturers have long manufactured screws with parameters that most closely match the torque and power of the engines. In most cases, the smaller the screw diameter, the higher the pitch and vice versa.
- In the case of lower revolutions, reduce the screw pitch. Here it is worthwhile to take into account the fact that reducing the indicator by 1 inch will increase the speed by 200. With the increased cycle, it is necessary to perform the above actions with exactly the opposite.
- It is recommended to choose a screw with a high disk ratio, which will maintain a stable speed at maximum speed.
- Use better stainless propeller. The price of products of this category starts from 4000 rubles. Their installation will allow to slightly increase the speed.
Before proceeding directly to the acquisition of the outboard propeller, it is worth understanding the distinctive features of the model range of the affordable price category. It is no secret that most types of products that are supplied to the domestic market are made in China. However, there are also defining differences in the quality of screw manufacture by individual plants. The huge role played by the materials used, the build quality, the nature of the outer coating. Naturally, these figures differ from budget manufacturers and manufacturers of premium products.