According to NAM Roger's book The Wooden World, An Anatomy of the Georgian Navy, the weekly ration of a British sailor in the 18th century was:

7lb of bread, 7 gallons of beer 4lb of beef 2lb of pork 2 pints of peas 3 pints of oatmeal 6 oz of butter 12 oz of cheese.

The "bread" was normal when in port, but issued as biscuits at sea. Stockfish (dried fish) was occasionally issued. Vegetables and fruit were eaten in port, but not at sea as they were hard to preserve.

The food was generally of high quality and carefully packed in barrels, so it would last as long as the preservation techniques of the time would allow - thanks to the miasma theory of disease at the time - the idea it was caused by bad smells, it was widely thought the smell of rotting food would directly cause disease so a lot of effort went into the preservation of food. It seems cheese was the hardest item to preserve, so not popular with crews, who disliked the taste, and captains (who thought the smell of it might cause disease).

Which navy?

Sorry for the delay to answering this. I wrote an article (it's only the first half, there's so much material) that exactly answers your question: Salt Pork, Ship's Biscuit, and Burgoo: Sea Provisions for Common Sailors and Pirates, Part 1