First,the function of the propeller

The function of the propeller is to turn the power of the ship's main engine into the power of the ship's forward (or retreat).

The various mechanisms that propel the ship forward are collectively referred to as ship propellers. The ship propeller has propeller, water jet propeller, rotary propeller, round wheel and Z-shaped propeller. Among them, the propeller structure is simple, light weight, high efficiency, reliable, is currently the most widely used ship propulsion.

A propeller is a reaction-type propulsion device in which the propeller rotates backwards (or forwards) and thrusts against the water (ie, backward) thrust when the propeller rotates.

Second,the structure of the propeller

The propeller consists of a blade and a hub, as shown in Figure 8-2. A paddle is a component of a propeller that produces thrust, usually with three and four lobes. The hub is the connecting member of the paddle and the paddle shaft. Some propellers are also equipped with a shroud (streamlined paddle), so that the propeller tail linear smooth, reduce the propeller work resistance.

1.foliage and leaf back
The side of the blade seen from the stern to the bow is called the leaf and the other side is called the leaf.

2.led edge and with the side
Propeller forward when the blade first into the water side called the edge, after the side of the water called the side.

3.leaves and leaves slightly
The blade is connected to the hub at the blade root, and the end of the hub is called the leaf tip. Usually thick roots and thinner leaves.

4.the right propeller and the left propeller
The propeller is spinning the clockwise propeller called the right propeller, and the forward rotation is counterclockwise. The propeller is called the left propeller.

5.external rotation and internal rotation
For the paddle boat, the left-hander left-handed, right-hander called outside the spin; In order to avoid entrainment of floating objects and damage to the blade, the ship generally use more external propeller.

Third,the common defects of the propeller

Common defects in the propeller are corrosion, wear, cracks, bending and breaking.