Various combinations of derricks, winches and deck cranes are used for the 6. Greater flexibility in loading and unloading, together with cargo segregation and improved stability, are possible using the tween deck spaces. One or more separate decks are fitted in the cargo holds and are known as tween decks. The hatch covers are made watertight and lie upon coamings around the hatch which are set some distance from the upper or weather deck to reduce the risk of flooding in heavy seas.
Hatch covers of wood or steel, as in most modern ships, are used to close the hatch openings when the ship is at sea. Hatches are made as large as strength considerations will allow to reduce horizontal movement of cargo within the ship.
Access to the cargo storage areas or holds is provided by openings in the deck called hatches. The general cargo consists of as large a clear open cargo-carrying space as possible, together with the facilities required for loading and unloading the cargo. The particular features of appearance, construction, layout, size, etc., will be examined for the following ship types: (1) General cargo ships. Khaled Atua Ship Construction 1- Ship Types and Features Several basic ship types are considered.
