This ship series was originally designed as a three-deck version (738-741). However the last two ships (BNR 742 and 743) were built with four decks. In order to carry a large number of high-weight containers and Mafis, a corresponding ship deadweight was chosen. To achieve a reasonable speed of 18.5 knots, however, a main engine capacity of only 10,800 Kilowatt could be installed leading to an extremely low fuel consumption. The single screw design can be manoeuvered in port using an additional bow thruster and a stern thrust propeller. The arrangement of the stern ramp, the internal ramp and the loading deck permits fast loading and unloading, so considerably reducing time in port. The addition of the fourth deck increased lane metre capacity by 35%. In this way the converted ship is capable of carrying more large volume cargo without significantly influencing its deadweight or speed.