Ore-bulk-oil carrier

An ore-bulk-oil carrier, also called a combination carrier or OBO, is a ship that carries wet or dry cargo. The idea is to reduce the number of empty voyages in which large ships carry cargo one way and are empty for another.
OBO carriers are today not as common as in the 1970s and 1980s.
One of the most famous OBO carriers is the "Derbyshire". It sank during a typhoon in 1980 in the Pacific.