Why does my radio in my ship keep cutting out when I turn up

Why does my radio in my ship keep cutting out when I turn up the volume?
when I turn up the volume, the radio "shuts off" then turns back on and keeps doing this till I turn down the volume

it is common in boats for the voltage source at the radio to be weak. Thin wiring and corroded connections create resistance in the power wiring, which results in a voltage drop when the deck's amplifier requires more current. The problem is made worse by the fact that there is no metal chassis like in a car, so more voltage drops are presented into the ground wiring.

The simplest fix is to run a new power and ground wire straight to the battery from your radio. based on the length, some 14 gauge or 16 gauge speaker wire should do nicely. Connect the deck's black wire to your battery's negative terminal, and the yellow wire to the positive terminal. Put a ten amp fuse on the wire near the positive terminal.

If your deck is wired to turn on and off through a key switch or accessory switch, then leave the deck's red wire connected as it's now, it does not require any important current. Otherwise you may be able to add the red wire with the yellow wire and connect both to the positive terminal.

MECP certified car audio installer with ship experience
I've had to fix this problem in some number of boats.

Your radio watts isn't strong enough.. you are overloading your radio.. you will need a after market amp.

clearly it is possessed.

Could be your major speaker has small crack . when you deliver more amps the small crack opens up cutting the volume off.