Exam Question

Improving rudder efficiency is paramount for enhancing overall propulsive effectiveness, leading to significant fuel savings and improved vessel maneuverability. This is achieved by optimizing the hydrodynamic forces (lift and drag) acting on the rudder, particularly by recovering energy from the propeller's rotational slipstream.
### (a) Rudder Thrust Fins (e.g., Becker Flaps)
**Concept & Principle:**
Rudder thrust fins, also known as Becker flaps, are movable high-lift devices attached to the trailing edge of the main rudder. They function as a post-swirl energy recovery device. The primary principle is to convert a component of the rotational flow (swirl) exiting the propeller into useful axial thrust, while simultaneously increasing the effective camber of the rudder airfoil.