I have had this experience several times and I have heard possible explanation, firstly you must remember that TV sets are designed for use ashore where the power supply consists of one live wire and a Neutral wire which is connected to Earth at the Star point of the supply Transformer. On a ship we have two live wires, and no "Neutral".
The chassis of the TV can be used as an "Earth return" the same as with a car, cheaper than having a 2 wire plus Earth system,(so longer as the chassis is doubly insulated) and another point is that the aerial amplifier system is Earthed.
If the screening cable of the aerial wire is Earthed to the "Neutral" (actually live Phase) chassis in the TV and to a real, Ship's Earth in the aerial amplifier, we have an obvious problem! On a ship, live power from the chassis will be fed into the screening cable and be connected to the real Earth at the amplifier creating a direct path from the "Neutral" to Earth. This is also potentially hazardous.
With signal cabling the screen is only supposed to be Earthed at one end, to prevent current flowing through the screen and inducing a current in the signal wire, which will cause interference to the signal.
If the fault is in the power supply a 1:1 isolating transformer in the power supply will resolve it, if it is in the aerial system an indirect coupler can be fitted in the lead which isolates the Earth and transmits the signal by Capacitive or Inductive coupling, or alternatively the Screening on the aerial wires can be stripped back so that they do not connect to the TV sets.
I am sure that a little experimentation will produce a SAFE fix.
Happy New Year!
It is always better to ask a stupid question than to do a stupid thing.