Stowage Factors

This is an all important area as much of the structure of commercial ship trading depends on the amount of cargo a vessel can carry, and the ‘freight’ a carrier will receive or a shipper pay for the transportation of that cargo.Gradually the international shipping market has moved away from traditional methods of cargo measurement based heavily on ‘imperial’ or ‘local’ units, towards the all-embracing metric system. Thus nowadays it is more usual to encounter ‘metric tonnes’ rather than ‘long tons’ or ‘short tons’ to describe the weight of a bulk commodity, or measurement in ‘metres’ rather than in ‘feet’. The one exception to this drift towards metrication is that of ‘stowage factors’, which is the amount of space occupied by a given quantity of any dry commodity whatever its mode of carriage, whether it be ‘loose’ (e.g. ‘in bulk’) or ‘contained’ (e.g. in bags or on pallets). It is usual nowadays to describe the stowage factor of a commodity as ‘per metric tonne’ rather than as ‘per long ton’, but the stowage factor itself is usually described in terms of ‘cubic feet per tonne’ instead of ‘cubic metres per tonne’, mainly because it is so much easier for practitioners to remember stowage factors of particular commodities in terms of cubic feet rather than in terms of cubic metres. Some cargoes (like iron ore) stow heavily and others (like coke) stow lightly. In fact, reference to ‘Cargoes’ will reveal that iron ore will stow around 13 cubic feet per tonne, whilst coke requires around 80 cubic feet per tonne. That means that a given space can contain around six times more tonnes of iron ore than of coke. In terms of ships, imagine you are operating a bulkcarrier of 55,000 tonnes deadweight cargo capacity (dwcc), with a cubic capacity in her cargo holds of two million cubic feet.