What phenomenon occurs when the stern of a vessel moves laterally due to propeller side force?

• A. Bow effect
• B. Pulsation effect
• C. Passing ship effect
• D. Propeller lift

Answer: (C)

The situation described involves the lateral movement of the stern of a vessel primarily due to the influence of propeller side force. This force occurs when a vessel moves through the water, and as the propeller rotates, it creates a lateral thrust that can cause the stern to move sideways.

The correct answer focuses on the phenomenon known as the "passing ship effect." This effect specifically pertains to the behavior observed when a vessel is operating in close proximity to another vessel, causing changes in the flow dynamics around both ships due to their respective propeller actions and hull designs. When one vessel passes another, the water can be disturbed, leading to unexpected lateral movements.

When considering the other options:

• The "bow effect" refers more to the tendency for the bow of the vessel to rise or fall as the speed changes or as a result of hull shapes, rather than lateral movement of the stern.

• "Pulsation effect" typically relates to the changes in pressure or water flow resulting from various factors but is not specifically aligned with the lateral stern movement caused by propeller side force.

• "Propeller lift" generally refers to vertical forces generated by the propeller but does not encapsulate the lateral movement phenomena from propeller influence.

Understanding these dynamics