What is a single deck and what is a double deck?

Simply put, a single-deck ship is only one all-access deck, and a double-deck ship has one or at least two decks in the cargo area. In fact, there are three-decked ships and multi-decked ships, such as roll-on/roll-off ships, passenger ships and so on. Two or more decks are mainly needed for loading cargo. Because some cargoes are stacked too high and will crush the lower cargoes, multiple decks are needed for loading. General grocery ship or multi-purpose ship, the deck height should not exceed 7 m. So some larger grocery ships have three decks. However, with the process of ship specialization and containerization, there are fewer and fewer general cargo ships. Everyone will see less double or multi-deck cargo ships. Roll-on/roll-off ships and passenger ships set up multi-deck, there is no need to say why.