A combined vessel is a ship which can carry both wet and dry bulk cargoes.
About 20 years ago the fleet of combined vessels comprised about 400 units equalling about 45 mill. tons deadweight. However, during the last decade most of the larger oil companies imposed an age limit of maximum 15 years on combined vessels which in effect stopped the contracting of such tonnage and thus the renewal of the fleet.
Although the possibility exists to extend beyond the 15 years with upto 5 years more through the classification societies' Conditions Assessment Programme (CAP), the tankers and gas carriers by comparison enjoy a 20 years' age limit plus a CAP of upto 10 years. As a result, the fleet of combined vessels today comprises 150 units only or about 15 mill. tons deadweight. During the last 15 years the Bulk Sea Transportation (wet and dry) has increased by an average of about 60% per ton/mile basis - crude and oil products alone by as much as 90% per ton/mile basis. many combined vessels lost their trading grounds of PROBLEMS/WEAKNESSES OF THE PAST the past and entered into "new trades" with bad The age limitation imposed was very much performance. a result of elderly, substandard operated and At the same time, i.e. the early 1990'ies, maintained 2nd and 3rd generation combined vessels many oil companies experienced stability problems performing poorly at loading terminals in the North with tankers and combined vessels and demanded a Sea and discharging terminals in the USA. For centreline bulkhead in tankers to be chartered for example, with the collapse of the Soviet Union, period business. The 39 new 4th generation OBOs 283 OPTIMUM 2000 delivered during the 90'ies did not meet this SAFER AND STRONGER SHIP - TECHNICAL centreline bulkhead requirement either. Thus the IMPROVEMENTS general objection from oil companies to charter The last two generations of combined OBOs has been the lack of stability compared to the vessels are of the double hull/double bottom centrelined tanker together with some distrust as to construction. The double bottom is strengthened to the tightness of vessels' hatches. Most new tankers carry heavy cargoes such as iron ore and to facilitate delivered during 1980'ies were built without discharging of dry bulk cargoes by large grabs etc. In centreline bulkheads as well. addition, the introduction of the centreline bulkhead increases the strength of the vessel's hull and provides a stiff support for the deck and hatch coamings. All known technical and operational weaknesses of the combined vessels of the past have been rectified in the OPTIMUM 2000 design. The OPTIMUM 2000 is therefore of a stronger and safer construction than any other combined vessel, bulk carrier, or double hull/double bottom tanker.
OPTIMUM 2000 - midship section 284 OPTIMUM 2000 OPTIMUM 2000 - hatch c