On a single-screw ship, moving ahead with the propeller rotating clockwise, the bow will walk to which side?

• A. Center
• B. Port
• C. Starboard
• D. None

Answer: (B)

Propeller walk is the sideways movement a hull experiences because the propeller swirls the water as it delivers thrust. On a single-screw vessel, the direction of that swirl depends on how the propeller rotates.

When moving ahead and the propeller turns clockwise as seen from the stern, the water behind the propeller is deflected in a way that the reaction on the hull pushes the bow toward the port side (the stern yawing toward starboard). In other words, the propulsion-induced transverse force makes the bow walk to port. If the rotation were reversed, the bow would walk to starboard.

Center or none would imply no lateral motion, which isn’t the case here because the propeller’s rotation always generates a sideways force on a single screw.