Commercial vessel

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Commercial vessel
Two modern container ships in San Francisco

Commercial vessels or merchant ships can be divided into three broad categories: cargo ships, passenger ships, and special-purpose ships.[43] Cargo ships transport dry and liquid cargo. Dry cargo can be transported in bulk by bulk carriers, packed directly onto a general cargo ship in break-bulk, packed in intermodal containers as aboard a container ship, or driven aboard as in roll-on roll-off ships. Liquid cargo is generally carried in bulk aboard tankers, such as oil tankers, chemical tankers and LNG tankers, although smaller shipments may be carried on container ships in tank containers.

Passenger ships range in size from small river ferries to giant cruise ships. This type of vessel includes ferries, which move passengers and vehicles on short trips; ocean liners, which carry passengers on one-way trips; and cruise ships, which typically transport passengers on round-trip voyages promoting leisure activities aboard and in the ports they visit.

Special-purpose vessels are not used for transport but are designed to perform other specific tasks. Examples include tugboats, pilot boats, rescue boats, cable ships, research vessels, survey vessels, and ice breakers.

Most commercial vessels have full hull-forms to maximize cargo capacity.[citation needed] Hulls are usually made of steel, although aluminum can be used on faster craft, and fiberglass on the smallest service vessels.[citation needed] Commercial vessels generally have a crew headed by a captain, with deck officers and marine engineers on larger vessels. Special-purpose vessels often have specialized crew if necessary, for example scientists aboard research vessels. Commercial vessels are typically powered by a single propeller driven by a diesel engine.[citation needed] Vessels which operate at the higher end of the speed spectrum may use pump-jet engines or sometimes gas turbine engines.[c

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