While underway in fog, if you hear a signal ahead and a risk of collision exists, what must you do?

• A. Stop and reverse
• B. Turn to starboard immediately
• C. Increase speed to pass ahead
• D. Slow to bare steerageway and navigate with caution

Answer: (D)

The key idea is acting at safe speed when visibility is limited and there’s a potential risk of collision. In fog, you can’t rely on sight to judge distances or other vessels’ actions, so you must ensure you can take early and effective action. Slowing to bare steerageway means reducing speed to the minimum level at which you still have steering control and maneuverability. From that point, you can adjust course or stop if needed, and you can do so well in advance of any potential conflict with the other vessel you’ve heard signals from. This cautious approach minimizes the chance of collision because you have time to respond and can see, hear, or feel changes in the situation.

Other actions, like stopping and reversing, speeding up to pass ahead, or turning abruptly, would either not provide the necessary time to react, could create new risks for you or others, or simply violate the principle of proceeding at a safe speed to allow proper action. The recommended approach balances control, reaction time, and safety in restricted visibility.