Hopper (bulk carrier)

A hopper, in a bulk carrier, is the sloped tank structure in the lower wing of the hold, running between the inner bottom (tank top) and the side shell, that angles the cargo hold boundary so dry bulk self-trims toward the centerline and drains to the hatch for grab discharge. The matching upper wing (topside) tank slopes inward from the deck, so the cargo cross-section is an octagon that limits free-surface shift of grain and concentrates the cargo over the double bottom. The hopper and topside tanks double as water-ballast tanks for ballast capacity and trim control. Their slope angles, near the angle of repose of the cargo, let cargo flow clear during discharge with minimal hand-trimming.