A boat propeller is a type of fan that relays power by transforming rotational motion into thrust. Most boat propellers are made up of three or more blades usually spinning around a central shaft hence creating dynamics that match a rotating screw. The correct choice of propeller for your boat usually gives you the advantage of having a clean hull and a well-tuned engine. Propeller blades may vary from three blade to four blade and even to five blade propellers. There are various classes of propellers and most are the ground-adjustable propellers and the fixed- pitch propellers.
There are also marine propellers which are of different types and more information about them can be read here. There is the skewback propeller whose blade tips are swept back against the rotational direction. The blades are then tilted backwards along the longitudinal axis. This enables the propeller adopt a cup-shaped appearance therefore maintaining the efficiency of thrust and at the same time reducing cavitation. Cavitation is the process whereby vapor bubbles are formed in water close to a propeller blade in motion in regions of low pressure. It mostly occurs when the propeller is operating at a very high speed thus wasting power, creating vibrations, causing wear and tear ultimately damaging the propeller. There are two common types of cavitation; tip vortex cavitation and suction side cavitation.
Tip vortex cavitation is mainly brought about by low pressure forming at the core of the tip vortex usually brought about by fluid wrapping itself around the tip of the propeller. Suction side surface cavitation comes about when the propeller operates at high rotational speeds or alternatively when the load is heavy. Then there is the voith Schneider propeller which makes use of usually four straight blades which turn around a vertical axis. These blades usually provide thrust in any direction at any given time. Then there is the controllable-pitch propeller. This propeller comes with several positives associated with it such as enabling a sea vessel move backwards, ensuring least drag based on the speed employed and providing the ability to employ the vane stance which ensures the least water resistance when for instance the sails are used in place of the propeller. You can check out Propeller Depot to learn more about marine accessories now.
There is also the modular propeller which enables one have more influence over the performance of their boat in differing altitudes and when cruising. When choosing the right propeller one must consider the size which is mostly expressed in diameter and pitch whereby the diameter is twice the distance from the center of the hub to the tip of a blade while pitch is the forward distance a propeller travels during one revolution. Learn what to look out for when buying a boat here: https://www.huffingtonpost.com/internationallivingcom/buying-a-yacht_b_5983612.html.