Ore Bulk Oil Carriers (OBO) are vessels that can load various types of bulk goods, such as grains, ores or oil products.
However, this can never be done simultaneously. When after having been unloaded, a different type of bulk good is loaded the holds must be thoroughly cleaned first. Hence most of such vessels continue to carry the same type of cargo for long periods of time. A different trade will be opted for, depending on the demands of the market situation.