Which instruction corresponds to adjusting speed on both engines?

• A. Port/Stbd ahead
• B. Adjust speed on both engines
• C. All ahead, all back
• D. Steady as she goes

Answer: (B)

The main idea is controlling propulsion in a way that changes speed without pulling the ship off course. When you adjust speed on both engines, you change thrust on both propellers evenly. This smooths speed changes and keeps the vessel headed where you want, since there’s no differential thrust to create a turning moment.

If you only move one engine, you introduce unequal thrust, which can yaw or push the ship to one side. That’s not desirable when you’re trying to change speed while maintaining direction. Other commands either push one engine in a different direction (affecting steering), command both engines to full ahead or full astern (extreme changes rather than gradual speed control), or tell you to maintain the current speed and course. So the instruction to adjust speed on both engines directly matches the goal of changing speed symmetrically.