Channel 6: Intership safety communications.
Channel 9: Communications between vessels (commercial and recreational), and ship to coast (calling channel in designated USCG Districts).
Channel 13: Strictly for navigational purposes by commercial, military, and recreational vessels at bridges, locks, and harbors.
Channel 16: Distress and safety calls to Coast Guard and others, and to initiate calls to other vessels; often called the "hailing" channel. (Some regions use other channels as the hailing channel. For example, the Northeast uses Channel 9.) When hailing, contact the other vessel, quickly agree to another channel, and then switch to that channel to continue conversation.
Channel 22: Communications between the Coast Guard and the maritime public, both recreational and commercial. Severe weather warnings, hazards to navigation, and other safety warnings are broadcast on this channel.
Channels 24-28: Public telephone calls (to marine operator).
Channels 68, 69, and 71: Recreational vessel radio channels and ship to coast.
Channel 70: Digital selective calling "alert channel."