Skewing the blade changes the angle of its leading edge and face so pressure changes are spread more favorably through the rotation. The resulting reduction in cavitation and radiated noise is especially valuable to submarines that must combine speed with acoustic discretion. The Los Angeles class and Type 212 are cited as examples. Their screws also mark a stage before the wider move toward shrouded thrusters and impeller-like systems made exposed blade geometry less visible.
Notable Point · 25:07-26:09
Skewback propellers for fast, quiet submarines
Swept blade geometry helps submarine screws limit cavitation and propeller noise while sustaining high speed.