The increase in the number of specialist combination ships, such as ore-oil carriers, or OBO carriers, can only to some extent, or in a limited number of specific cases, be accounted for by the better utilisation of the cargo-carrying capacity (ore one way, oil back).
Ukukhula kwinani leenqanawa ezidibanisa ubuhule obubodwa, njengeenqanawa ezithutha i-oyile ekrwada, okanye izithuthi iOBO, zingafane okwexeshana okanye kwinani eliqingqiweyo zeziganeko ezikhethekileyo, ziqwalaselwe ngokusetyenziswa ngcono kwezithuthi ezithwala umthwalo (i-oyile ekrwada ukuya, i-oyile ekrwada ukubuya).