First, an overview of early propulsion propellers propeller with blades molded into one, the propeller pitch angle i98s constant. 1908 SEFELE company researching and manufacturing the first variable-pitch propeller, its blades are manufactured separately from the shell, blade screws installed on the shell casing and on the oar rotation. This is what today we use the variable-pitch propeller, variable pitch propellers for short, also called controllable pitch propellers.  

Compared with ordinary fixed-pitch propeller, the main advantage of variable pitch propellers can be summarized as follows: 1. simplifies host and the whole power structure. Variable pitch propeller engines can save a reverse gear, or turbo engines can save them back level, and increase power to reverse it. In addition, variable pitch propellers provided conditions for constant speed engines operating. 2. improving the manoeuvrability of the ship. Variable pitch propeller is easy to realize remote control, need to change speeds, only need a remote control device to change the pitch angle, can be realized from between zero and maximum speed stepless speed regulation, and in the case of hostnon-stop without reversing, you can easily hang. 3. improved the ship's maneuverability. Using the variable pitch propeller, you can host without stopping any super low speed navigation, and if necessary, you can also make propellers worked alternately to the ahead or astern to ensure efficiency. In addition, variable pitch propellers improved the ship's wind performance.