For GMDSS, when may a compulsory vessel not be allowed to leave port?

Correct Answer: Option A — When the vessel has replaced a required piece of GMDSS-related equipment but its performance has not been verified or logged

Under 47 CFR Part 80 and SOLAS, a vessel cannot depart port if newly installed or replacement GMDSS equipment performance has not been formally verified, tested, and recorded in the station log to ensure system integrity.