Bulk Carrier

Bulk carriers, often simply called bulkers, are the workhorses of the dry-cargo trades. They carry commodities that are shipped loose in enormous quantities: iron ore and coal for industry and power, grain to feed populations, and materials such as bauxite, phosphate, cement and steel. Their design is dictated by the need to load and discharge these cargoes quickly and to keep the ship's structure sound while doing so. A typical bulker has a single deck, a series of large box-shaped cargo holds, and wide hatch openings closed by steel hatch covers that allow grabs, conveyors and shore loaders to reach the cargo directly.

Inside the holds, sloping hopper tanks at the bottom and topside tanks at the corners help the cargo settle toward the centre and self-trim, and they double as ballast tanks. Bulk carriers are described by size classes that correspond to the trades and ports they can serve: handysize and handymax or supramax for smaller ports and varied cargoes, panamax for vessels sized to transit the Panama Canal locks, and capesize for the largest ships, which are too big for the canal and must sail around the capes on the iron ore and coal routes.

Bulk carrier operations carry particular hazards that shape their regulation. Loading and discharging very heavy cargoes rapidly imposes large stresses on the hull, so loading must follow a sequence that keeps bending and shear forces within limits. Some cargoes can shift or liquefy when wet, threatening stability, and others can emit dangerous gases or deplete oxygen in the holds. The industry's loss record led to strengthened structural rules and to the IMSBC Code, which governs the safe carriage of solid bulk cargoes, their moisture limits and their stowage.