What is the primary reason a ship would need to set a watch on VHF-FM Channel 16?

Setting a watch on VHF-FM Channel 16 is essential primarily for listening for emergency announcements. Channel 16 is designated as the international distress, safety, and calling frequency. This means that vessels must keep a listening watch on this channel to ensure that they can receive urgent distress calls from other vessels, alerts of emergencies, and important safety information.

In maritime operations, safety and immediate responsiveness are critical. If someone is in distress or if there is an urgent announcement related to maritime safety, it is vital for vessels nearby to be aware and able to respond quickly. Thus, maintaining a watch on this channel helps ensure that calls for help can be heard and that appropriate action can be taken.

While other channels or activities may involve communications, the primary and most critical function of monitoring Channel 16 is to stay updated on emergency situations, which directly aligns with safety protocols in maritime operations.