There are basically two types of ‘combination carrier‘ capable of transferring successfully from the distinctive dry-bulk market to what might be termed the ‘wet-bulk trades’. Both tend to be large ships in excess of 60,000 tonnes deadweight, frequently more than 100,000 tonnes deadweight. The most common (and usually the smaller) type is the ‘0B0’ (‘Ore/Bulk Oiler’) which unlike the impression given by its name, has sufficient cubic cargo carrying capacity to enable it to carry economically not only heavy, dense ore, but also lighter stowing commodities such as coal and even grains. The distinctive feature of an OBO is that the same cargo compartment that has been used to carry a dry-bulk commodity can be discharged and then prepared for the carriage of a cargo of crude oil. Those Charterers engaged in the dry and wet trades may prefer in ideal circumstances to employ specialised bulkcarriers or tankers, as the case may be, but frequently Owners of an OBO have an in-built freighting advantage over their specialised rivals, in that ballast runs can be reduced because of their vessel’s ability to indulge in two markets instead of just one. Thus, even though the upkeep of these vessels is frequently higher than for a simpler ship specialising in just one market sector, encouraging profits can be achieved from such ships given efficient marketing and voyage planning. Here the reference to ore is accurate, Ore/Oilers having separate small cargo compartments specifically designed for the carriage of heavy ores, the crude oil part of their cargo commitments being carried separately in oil-tanks. Ore/Oilers can carry dry-bulk commodities other than ores, but they would fill their cargo spaces very quickly and be unable to use their full deadweight. Not only that, but because they are not constructed with self-trimming facilities, extra time and expense would be needed to ‘trim’ the cargo surface level. Consequently, it is very unusual for Ore/Oilers to be engaged in the carriage of other than iron-ore or crude oil, and they tend to be in excess of 100,000 tonnes deadweight, this size of cargo being particularly attractive to those engaged in the steel making industry.