Different Types of Boat Propellers
A boat propeller is a mechanical device that propels or pushes the boat through the water. It consists of revolving shafts, which are typically powered by boat motors, and blades, which are responsible for biting or gripping into the water. Boat props can be categorized according to the style and amount of blades they used, their pitch measurement and diameter, as well as the type of materials they’re made from.
A three-blade propeller is the most common type of propeller, and it is also usually the fastest (the exception being that on other high performance boats, a four-blade propeller allows for greater speeds). The propeller’s three, curved blades spiral around a central device called a hole shot, which connects the propeller to the boat’s engine. The curves help improve the propeller’s traction, or bite in the water.
A four-blade propeller allows a boat to stay on plane while the engine runs at low levels of rotations per minute (RPMs). This means that this type of propeller is better than its three-bladed counterpart at keeping a steady or even cruising speed. This is good both for trolling, a type of fishing in which you drag baits/lures behind a steady-moving boat. Also, a four-bladed propeller can be adjusted or trimmed to increase the transom height, which helps increase the speed of the boat.
A cupped blade can be integrated into four-blade and three-blade propeller designs. This type of blade has curved lips, which allow for better grip or bite in the water (while a blade on a three-blade propeller is already curved throughout, “cupped” specifically refers to curved outer edges). When the propeller is positioned so that it operates close to the surface of the water, a cupped blade will help increase the overall speed of a boat.
Pitch and Diameter
Propellers are also classified according to their pitches and diameters. The pitch is the theoretical distance that a boat will be able to travel per propeller rotation, while the diameter is the distance across the circular device that the blades are typically attached to. Nevertheless, while increasing the propeller’s pitch will increase the boat’s top-end or overall speed, you will decrease or lose the acceleration.
Boat propellers are usually made from one of two materials: stainless steel or aluminum. While the more-popular aluminum propeller is less expensive, it is also more prone to damage. A stainless steel propeller is more durable and much stronger than its aluminum counterpart, and can also be heat-treated for increased protection from dings and scratches.