FCC Marine Radio Operator Permit
To operate a radio on board a commercial vessel, you must have a Marine Radio Operator Permit (MROP) issued by the Federal Communications Commission (FCC).
To obtain the permit you will need to pass the MROP exam which can be done at the Captain School USVI on most Mondays and Wednesdays or by appointment.
The study guide is available here by clicking the link.
The permit is issued for life. There is a one time fee of $125.