Which instruction describes moving propulsion on both engines in opposite directions?

Which instruction describes moving propulsion on both engines in opposite directions?

• A. All ahead, all back
• B. Port/Stbd ahead
• C. All stop
• D. Neutral

Answer: (A)

Moving propulsion on both engines in opposite directions creates a turning moment that rotates the vessel about its centerline rather than driving it straight ahead or backward. When one engine pushes ahead and the other pushes astern, the thrusts act on opposite sides of the hull, producing yaw while minimizing forward or backward translation. This is the maneuver used to reorient quickly in tight spaces or when a sharp turn in place is needed. All ahead or all back would drive the ship forward or backward as a whole, without creating the yaw needed for rotation. Neutral or stopping propulsion produces no thrust, so there’s no turning moment either.

Moving propulsion on both engines in opposite directions creates a turning moment that rotates the vessel about its centerline rather than driving it straight ahead or backward. When one engine pushes ahead and the other pushes astern, the thrusts act on opposite sides of the hull, producing yaw while minimizing forward or backward translation. This is the maneuver used to reorient quickly in tight spaces or when a sharp turn in place is needed.

All ahead or all back would drive the ship forward or backward as a whole, without creating the yaw needed for rotation. Neutral or stopping propulsion produces no thrust, so there’s no turning moment either.