This is part of the description of the cargo-carrying capacity of the ship. It is sometimes termed “Grain space capacity” or “Grain space”. If the ship is to carry dry bulk cargo, in granular or particle form, the cargo compartments for the cargo must be described in such a way that it can be calculated how many tonnes the ship can carry. The stowage factor of the commodity would be used in such a calculation. The volume of the cargo compartments is measured from side to side, even between the ship’s frames, because that is the manner in which a dry-bulk cargo will flow when loaded into the ship. Even the hatchways are included in the measurement. The grain capacity is the cubic volume in either cubic metres (“cu.m.”) or “cubic feet” (“cu.ft.”).
The grain capacity is larger than the “bale capacity” of a ship, which can carry mixed, general cargoes, and the ship’s sides and frames are separated from the cargo by side-battens and other forms of dunnage.