With the starboard screw ahead and the port screw astern, the boat will ______ in a leftward direction.

With the starboard screw ahead and the port screw astern, the boat will ______ in a leftward direction.

• A. Spin
• B. Pivot
• C. Drift
• D. Veer

Answer: (B)

When two propellers push in opposite directions on opposite sides, they create a turning moment about the boat’s vertical axis. This yaw force makes the hull rotate rather than simply move straight ahead or astern. Specifically, with the starboard screw ahead (forward thrust on the starboard side) and the port screw astern (backward thrust on the port side), these opposing forces generate a torque that turns the boat to the left. The result is a pivot around the boat’s center rather than a straight dive forward or backward. This is why pivot is the best description: the vessel rotates about its centerline in place. The other terms describe different motions—drift is movement with external forces like current, veer is a change in direction due to wind or current, and spin implies a more free-form rotation.

When two propellers push in opposite directions on opposite sides, they create a turning moment about the boat’s vertical axis. This yaw force makes the hull rotate rather than simply move straight ahead or astern.

Specifically, with the starboard screw ahead (forward thrust on the starboard side) and the port screw astern (backward thrust on the port side), these opposing forces generate a torque that turns the boat to the left. The result is a pivot around the boat’s center rather than a straight dive forward or backward.

This is why pivot is the best description: the vessel rotates about its centerline in place. The other terms describe different motions—drift is movement with external forces like current, veer is a change in direction due to wind or current, and spin implies a more free-form rotation.