During which situation is the tug considered to have a larger lever effect on the stern movement?

• A. All stop
• B. Slow speed
• C. Astern bell
• D. Ship at rest

Answer: (C)

The tug is considered to have a larger lever effect on the stern movement during an astern bell situation. When a vessel receives an astern command, it is essentially directed to move in reverse, which can increase the effectiveness of the tug’s force on the vessel's stern. The tug's towing line exerts a pull at a distance from the pivot point of the ship, creating a larger lever arm.

This lever arm is crucial when attempting to maneuver the vessel, especially in tight quarters or during specific movements, as it amplifies the turning force applied by the tug. In contrast, during situations like all stop, slow speed, or ship at rest, the dynamics of motion and the influence of the tug are not utilized to the same degree. The tug's effectiveness diminishes when the ship is stationary or moving slowly, as the ship's momentum and situational factors play a reduced role in the lever effect that the tug can impart on the stern movement.