If a coxswain doesn't stand a night watch for 30 days, what must they undergo?

When a coxswain does not stand a night watch for 30 days, they are required to undergo Required Familiarization Training. This training is essential to ensure that personnel remain proficient and familiar with the operational duties and responsibilities associated with their roles on the water, particularly the specific skills needed for night operations.

The purpose of this training is to refresh the coxswain's knowledge of navigation, safety protocols, and any changes in procedures or equipment that may have occurred during their absence from active duty. It helps maintain operational readiness, ensuring that the coxswain can effectively respond to any situations that may arise during their watch.

The other options, such as refresher safety training, advanced tactical training, or operational readiness review, serve different purposes and contexts within the Navy's training framework. However, for the specific circumstance described—where the coxswain is returning to duty after not standing night watch—the required familiarization training is the correct response to address their readiness and competency for the role.