Decks: The number of decks depends entirely on the trade and cargo for which the ship is designed. On some liner trades she may have three or four; passenger ships will have many more. Ships designed to carry cars may have several portable decks. On the other hand, tramp vessels carrying bulk cargoes may only have one deck.
Deep Tanks: These are holds with facilities such as wash plates, pipelines and oil-tight hatches so that they can be used for the carriage of liquid cargoes or water ballast.