Ship bale and grain capacity measurements are provided by shipyards for dry cargo ships. Ship bale and grain capacities are used for measuring cargo space availability for bulk or non-bulk cargoes.
Ship bale and grain capacity measurements give the actual volumes available for cargo. Grain capacity is the space that is available for liquid-type cargo, like bulk grain, which can flow into every corner. Bale capacity is the space that is available for bagged or baled cargoes. Generally, a ship’s bale capacity is about 7–10% less than grain capacity.
Ship bale and grain capacity measurements can be expressed in either cubic feet or cubic meters. Reference books such as Lloyd’s Register nowadays use the metric system. However, a large proportion of dry cargo market practitioners still use cubic feet when describing the stowage factor of cargo, and so all involved in this aspect of the shipping industry needs to know that:
1 cubic meter = 35.3158 cubic feet
as conversion calculations from one measurement system to the other will frequently be required.
Ship grain capacity is the capacity of cargo spaces measured laterally to the outside of frames, and vertically from the tank tops to the top of the under weatherdeck beams, including the area contained within a ship’s hatchway coamings. Grain capacity is therefore an indication of space available for any bulk cargo, not just for bulk grain.
Ship bale capacity is the capacity of cargo spaces measured laterally to the inside of frames or of cargo battens and vertically from the tank tops to the underside (or bottom) of the under weatherdeck beams, but again including the area contained within a ship’s hatchway coamings. Bale capacity is therefore an indication of space available for other than a bulk commodity such as bagged or baled goods.
In the shipping business, dry cargo ships are frequently described in different ways. RO/RO tonnage might be referred to in terms of available ‘lane-meters’, or a containership by the number of TEU (Twenty-Foot Equivalent Unit) that it is capable of handling. However, depending upon the cargo, general cargo ships and bulk carriers might be described in terms of summer deadweight (DWT) or grain capacity or, more probably in the case of general cargo ships, in terms of bale capacity.
Ship Bale and Grain Capacity Example:
It might be sufficient just to know a ship’s available deadweight tonnage (DWT) to assess cargo capacity, assuming that no draft limitations anywhere on a voyage.
From the eventual available deadweight tonnage (DWT) must be deducted the ship’s constant weights (stores, freshwater, lubricants, spares, weight of the crew member). A ship’s constant weight is rarely critical but must be accounted for. For a ship around 15,000 DWT – 25,000 DWT (Summer Deadweight Tonnage), the ship’s constant is around 250-350 metric tonnes. For a ship above 35,000 DWT (Summer Deadweight Tonnage), the ship’s constant is around 400-500 metric tonnes
The other important deduction is that of bunkers remaining on board of a ship, and here it may be necessary to obtain appropriate data from the ship’s managers or captain. In the meantime, let us assume we have reached a suitable figure for DWCC (Deadweight Cargo Capacity). Regrettably, this is not the end of the problem. In theory, by dividing a ship’s grain or bale capacity by the stowage factor (SF) of the cargo to be loaded, we reach volume capacity. This maximum amount of cargo that can be carried within available cargo compartment space must then be compared with the available cargo weight. The smaller quantity is the restriction with which the ship’s operators must comply. It is normally the available deadweight which proves to be the limiting factor but, occasionally, a high stowing cargo such as coke or certain agricultural products will restrict tonnage intake. Additionally, it may be necessary to load several grades or types of cargoes, each requiring a separate cargo compartment and possibly causing, therefore, an inability to use all a ship’s cargo space.