Split–hull hopper barge or split hopper barge, a self-propelled cargo vessel with a large open hold between two hull halves. The hull is hinged at the deck and held together by hydraulics. When unloading, it splits apart, letting its cargo drop straight down. Each hull holds enough air to support the weight—even when the middle opens and cargo drops. It usually carries Sediment and dredged material, sand, silt, mud, gravel from waterways and channels. It also carries rock, concrete, construction

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The Barge Guide - Different Types and Functions - Pile Buck Magazine