A marine propeller is the core component of a ship's propulsion system, an impeller-type mechanical device that propels a ship forward/backward in water by rotating to agitate the water and generate a reaction force. Core Points: 1. It relies on the rotation of airfoil-shaped blades to create a water pressure difference between the two sides of the blades, generating an axial thrust that is transmitted to the hull.​2. It is commonly designed with a 3-6 blade structure to adapt to ships of different speeds and displacements, and is mostly made of corrosion-resistant and high-strength materials such as copper alloys and stainless steel.​3. Connected to the ship's main engine (diesel engine, electric motor, etc.) through a shafting system, its rotational speed and direction control the ship's speed and forward/backward movement.