The vessel is required to have a ships station licence and at least one person on board is required to have the appropriate operators licence.
some countries have stricter requirements. I have the Marine
Radio Operators Certificate of Proficiency (MROCP) from Australia
, which allows me to operate VHF
anywhere in the world. I also pay my annual spectrum usage fee of $45. I also have my Ham licence. Nobody has ever asked to see any of them.
There is little enforcement of these requirements and in an emergency
anyone is allowed to use any broadcast transceiver to request help. However if you are caught and prosecuted for misuse the penalties can be severe. Jamming, hindering priority radio traffic or illegal eaves dropping are where you might run into trouble.
Having good radio etiquette is the key. Having a licence generally implies you might be better in this regard. Listening to the dic#heads calling mayday because they're drunk and their beer
fridge is broken is comical and annoying. Also dealing with idiots that dont know radio procedure, the phonetic alphabet, words twice, over OR out and not over AND out makes it very difficult to communicate.
The purpose of the licensing and spectrum fees
are an attempt to ensure all can use these rf emitting devices without interfering with each other. This international system has worked well for over a century and through two world wars.