Stowage Factor

The stowage factor (SF) of a cargo is the volume in cubic metres (or cubic feet in the older imperial notation) occupied by one metric tonne of the commodity when stowed in a cargo hold, including all unavoidable waste space. Low stowage factor cargoes (dense materials such as iron ore or steel) fill the hold by weight before it is full by volume; high stowage factor cargoes (light commodities such as cotton bales or wood pulp) fill the hold by volume before the ship's weight-carrying capacity is exhausted. Published stowage factors are tabulated in cargo reference books and port authority data, though actual values vary with packing and condition. The chief mate uses stowage factors to calculate how many tonnes of each cargo can be loaded into each hold to fill it optimally without exceeding the hold's capacity or the ship's deadweight. Matching cargoes by stowage factor to hold volumes requires experience: a single hold typically contains only one type of cargo, and the planner must choose between filling by weight and filling by volume. The IMSBC Code (for solid bulk cargoes) and the Grain Code both specify individual stowage factors for their respective commodities, which inform hold planning and loading procedures. An incorrect stowage factor assumption can lead to taking more or less cargo than intended, affecting the commercial outturn and the ship's stability.