A ship may sail in international waters only under the flag of one state and is subject to the exclusive jurisdiction of that state.
This is the reason why almost all shipborne offshore radio stations flew the flag of a country which was nowhere near the area they were broadcasting to or from and they, generally, found a flag state whose rules of inspection were not as rigidly enforced as those of other nations.
These so called Flag States (for example Panama, Honduras or Liberia) operated such lax rules at the time in order to attract to their register as many ships as possible and consequently secure large incomes from the registration fees payable by ship owners.
Offshore broadcasters generally had to ensure that their transmitting equipment was located in the hold of their ships so that, particularly in the case of Panama, they could be legally classed as cargo and not broadcasting equipment.
HOLD Noun - cavity in a ship below deck where cargo is stowed. Also the area used to house transmitters on many radio ships.