Self-Unloading Bulk Carrier
The bulk carrier discharging by conveyor and boom rather than by grab: hopper holds, gate systems, belt and bucket elevators, and where the type pays.
A self-unloading bulk carrier discharges cargo through its own conveyor system rather than by grab, delivering it ashore over a slewing boom. Cargo flows by gravity from sloped hopper-shaped holds through controlled gates onto a tunnel conveyor beneath the holds, then up an elevator to the boom conveyor. Discharge is continuous rather than cyclic, and the rate does not depend on the receiving port having any equipment at all.
The full article will cover the arrangement and its trade-offs. The hopper geometry and the gate system cost cargo cubic and deadweight against a conventional box hold, the machinery adds capital cost and maintenance, and the system is sensitive to cargo that does not flow: wet, sticky, frozen or heavily degraded cargoes bridge over the gates. What the type buys is discharge rate and port independence, which is why it dominates short-sea aggregate, coal and cement trades and the Great Lakes.
It will treat the elevator types, the boom and its slewing and luffing arrangement, dust control and the environmental constraints that increasingly shape the trade, and the comparison against a geared bulk carrier working the same cargo with grabs.