Aux 1 Unit 10 Q5

Correct Answer: B) By reducing vibration and noise levels, particularly in vessels with higher speeds or in turbulent water conditions

Explanation: A high skew reduces vibration and noise levels by allowing the propeller blades to enter the wake flow more gradually, which is especially beneficial in turbulent water conditions or at higher speeds.

Correct Answer: B) It reduces the likelihood of cavitation by moving the cavitation bubbles further aft, away from the propeller blade roots.

Explanation: Aft rake helps reduce the likelihood of cavitation by moving the cavitation bubbles further aft on the propeller blades. This reduces the stress on the blade roots and lowers the risk of damage from cavitation.

Correct Answer: B) It improves the lifting characteristics of the propeller, enhancing the vessel's maneuverability, especially during acceleration.

Explanation: Aft rake improves the lifting characteristics of the propeller, which enhances the vessel's maneuverability, particularly during acceleration. This characteristic is especially beneficial for vessels that require quick changes in speed or direction.

Correct Answer: B) It allows the propeller to handle changes in water pressure more effectively, reducing the likelihood of damage and maintaining efficiency.

Explanation: High skew enables the propeller to handle changes in water pressure more effectively, which is particularly advantageous in environments with varying water conditions. This reduces the likelihood of damage and helps maintain efficiency.

Correct Answer: B) It improves the propeller's clearance from the hull, reducing the risk of vibration and improving propulsion efficiency.

Explanation: Aft rake improves the propeller's clearance from the hull, which reduces the risk of vibration. This helps improve propulsion efficiency by minimizing the interference of the hull with the propeller's water flow.

Correct Answer: B) It reduces the drag by minimizing the blade area exposed to the hull, which can improve fuel efficiency and performance at high speeds or under heavy loads.

Explanation: Aft rake reduces drag by minimizing the blade area exposed to the hull. This helps improve fuel efficiency and performance, particularly at high speeds or when the vessel is operating under heavy loads.

Correct Answer: B) It minimizes the effects of unsteady forces acting on the blades, improving the overall durability of the propeller.

Explanation: High skew minimizes the effects of unsteady forces, such as those caused by wake or turbulence, acting on the propeller blades. This improves the overall durability and performance of the propeller, especially under challenging operating conditions.

Correct Answer: A) It increases the propeller's resistance to cavitation by reducing the pressure fluctuations on the blades

Explanation: High skew in a propeller helps to distribute the loading more evenly along the blade, which reduces pressure fluctuations that can cause cavitation. This leads to a smoother operation and prolongs the propeller’s lifespan.