Tweendecker

A tweendecker is a general cargo ship with one or more decks between the weather deck and the bottom of the hold, the tweendeck, which splits the cargo space horizontally. The arrangement lets the crew stack lighter or crushable cargo above heavier goods and keeps incompatible parcels apart, useful in the mixed breakbulk trades the type was built for. Most carry their own cranes or derricks, so they load and discharge in ports without shore gear. Sizes run from small coasters to about 30,000 dwt. Modern hulls use movable tweendecks that fold or stow to free a clear box for containers. Containerization pushed the fixed tweendecker off liner routes, but the layout survives in the multipurpose vessel.