Coast Guard

Welcome to BoatUS - MMSI Registration

Take the Search out of Search and Rescue! Your VHF radio equipped with Digital Selective Calling (DSC) is the single most important piece of safety equipment you can have on board your vessel. DSC allows the radio to transfer information digitally, not just by voice, and to instantly send a digital distress alert to the Coast Guard. Part of that alert is a nine-digit Maritime Mobile Service Identity (MMSI) number that identifies your boat. The MMSI number is a bit like a phone number for your boat, and you should use the same MMSI number for all radios carried aboard and for some other emergency signaling devices. If you sell your boat, the MMSI number is normally transferred with it.

DSC-equipped VHF radios must have an MMSI number to function. That number must be registered in a database that is relayed to the Coast Guard for use in Search and Rescue. BoatUS has been authorized by both the Federal Communications Commission (FCC) and the U.S. Coast Guard to assign MMSI numbers only to vessels that meet the following criteria:

  • Used for recreation only
  • Not required by law to carry a radio
  • Do not make international voyages or communications

If your vessel is required to carry a radio on board (“compulsory equipped”) or if you ever intend to take your vessel out of US waters, then you need to obtain a Ship Station License and an MMSI from the FCC. Failure to do so may result in miscommunication or confusion in the event of an emergency that could delay a rescue.