Explanation: VHF Marine Channel 22A is specifically designated for routine communications with the U.S. Coast Guard, typically after initial contact is made on Channel 16. The regulation ensures that Channel 16, the international distress, safety, and calling channel, remains clear for emergencies and initial contact. Traffic is then shifted to Ch-22A to free up Ch-16 for other urgent calls. Channel 16 is incorrect because it's for distress, safety, and initial calling, not for extended routine conversations. Channel 80 is a private recreational working channel, not for official Coast Guard contact. Channel 13 is a bridge-to-bridge navigation channel used by vessels to communicate for safe maneuvering, not for routine contact with the Coast Guard.