In a move to clamp down on alcohol-fuelled behaviour, the Navy has banned drinking during work hours and curtailed the availability of alcohol on ships.
The new rules ban duty-free alcohol on board and increase the price for drinks at clubs on board.
Chief Rear Admiral Jack Steer said they are not about making the Navy alcohol-free, but managing sailors' drinking.
"Every now and then there's some inappropriate behaviour and our sailors get themselves into trouble, and generally it's related to alcohol.
"The change is long overdue, I believe. Our ships are hi-tech environments, we need everyone to be at their best."
Rear Admiral Steer said most people have taken the rule changes in a positive way.