The inner space of a ship between the limber boards of a double bottom and the decks is designed for carrying cargoes. We call this space a hold. Holds have different capacity. Big vessels have cargo holds divided into several separate compartments by watertight bulkheads. Each dry-cargo vessel has four or five holds. The holds have bilges which serve to give way for flowing the water which may condensate on metal bulkheads or collect on wooden flooring. The water collected in the bilges is pumped out by a hold pump. To protect the bilges from corrosion they are covered with cement or special anticorrosion substance, besides they are protected by limber boards.
The double bottom is covered with a removable wooden flooring. Cargo battens or "spar ceiling", as they are often called, comprises portable wooden battens fitted to the inner edges of the frames and so form a sheathing to the ship's side. "Spar ceiling" is made up of boards and arranged either horisontally, or vertically between frames. The purpose of this wooden sheathing is to prevent packages of cargo from damage by moisture which may collect on the side of the ship. The space so formed between the "spar ceiling" and the ship's side helps to provide a complete air space around the cargo and thereby improves ventillation. The "spar ceiling" should al-ways be kept in a good state. Each hold has a hatchway. The hatchway is the rectangular opening in the ship's deck. The vertical plating around the hatchway is called hatchway coaming.