On Limitation of Deadweight Gained by Enlargement Conversions of Tankers

Abstract

A large number of enlargement conversions has been effected hitherto and is likely to be increased more and more. In order to meet with this trend, MHI has made a serious study on a suitable type of ships to be enlarged by conversion and on a presumable limit to increase deadweight tonnage by means of the so-called "3 dimensional conversion" especially for tankers in view of both technical and commercial aspects. As the result, it has been proved that the tankers of 30,000-90,000 DWT built before 1965 are the expected type at present to be most economical for enlargement conversions. For instance, to take 50,000 DWT tankers, about 100% increase of deadweight is assumed to be the limit of enlargement conversions technically and about 70-80% increase to be most advantageous commercially, but from the viewpoint of the overall returns of the enlargement conversions it has been clarified from this study that about 100% or more increase shall be gained, depending upon the freight market of course. With regard to the larger tankers of more than 90,000 DWT, further investigation shall be made from various angles. And, this problem should be taken up for scrious study by both shipping and shipbuilding fields viewing of worldwide shortage of tanker tonnage, and of the tendency of rapid increase of tanker size.