The hull had four levels separated by three decks. The terminology for these in the 16th century was still not standardised so the terms used here are those that were applied by the Mary Rose Trust. The "hold" lay furthest down in the ship, right above the bottom planking below the waterline. This is where the kitchen, or galley, was situated and the food was cooked. Directly aft of the galley was the mast step, a rebate in the centre-most timber of the keelson, right above the keel, which supported the main mast, and next to it the main bilge pump. To increase the stability of the ship, the hold was where the ballast was placed and much of the supplies were kept. Right above the hold was the "orlop", the lowest deck. Like the hold it was partitioned and was also used as a storage area for everything from food to spare sails.