In fog with no targets on radar, but you hear a fog signal apparently forward of your beam, what action should you take to avoid collision?

• A. Reduce speed to minimum to keep on course, and if necessary take all way off and navigate with extreme caution until danger of collision is over
• B. Tune radar to detect targets more reliably
• C. Maintain your present speed and proceed on course
• D. Turn away from the signal and accelerate to pass by quickly

Answer: (A)

When fog signals indicate a vessel ahead even though you don’t see it on radar, you must act early and decisively to avoid a collision. The safest course is to reduce speed to the minimum practical speed and, if needed, bring the vessel to a stop and proceed with extreme caution until the danger is over. Slowing down lowers the relative closing speed, buys you time to detect the other vessel visually or on radar if it becomes detectable, and gives you a better chance to adjust course or speed smoothly as the situation develops. This approach reflects the obligation to take early action to avoid a collision and to maintain safe maneuvering in restricted visibility.

Tuning the radar won’t help if there are no detectable targets, continuing at current speed keeps you at higher risk, and turning away with acceleration could create a crossing or head-on scenario and still leave you with insufficient time to react if the other vessel is closer than expected.