Years ago, the FCC approved maritime "port operations" on UHF channels with non standard repeater pairs. some of these operations are simplex as well. It is all supposed to be low power.(2 watts) Some of the frequencies are in the GMRS band. It is not unusual for cruise ships to be on these frequencies. If you call the ship on the radio, be polite and simply indicate interference and request the vessel name and or to talk to the captain to get company contact information. Be sure to ID your GMRS station properly. Use simplex, don't use their input frequency! Mostly I would listen for clues as to what ship it is coming from and contact the IT or Telecom director at the Cruise company by writing a letter (and CC your local FCC field office) and simply request the use an alternate tone.