To achieve the ballast-free concept, HMD gave careful consideration to the special hull form with dead-rise, forward ‘engine room and deckhouse’ and a twin propulsion system with azimuth thrusters, in order for the vessel to retain its damage stability and control the trim and heel without ballasting.
Another key feature of this ship is the twin propulsion system with two azimuth thrusters. The smaller diameter of propellers fitted in the azimuth thrusters enables the vessel to achieve full immersion in all operational conditions.
LNG will be stored in two independent IMO type C tanks which are designed to contain the LNG with a minimum temperature of minus 165° C and maximum vapour pressure of 3.75 bar(g), and can be transferred to an LNG-fueled vessel at the rate of about 1,250m³/hour through the cryogenic flexible hoses without ballasting and/or de-ballasting operation. Additionally, the natural vaporising gas from the bunkering vessel and the returned boil-off gas from the LNG-fuelled vessel will be compressed up to 220 bar(g), stored in two sets of 40 feet container and used for propulsion fuel and electric.
As the vessel will incorporate a ballast-free design, it will not need to install a ballast water treatment system and it also doesn't have to comply with the Performance Standard for Protective Coatings for ballast tanks and related regulation, enabling maintenance costs savings.