Green feeder ship concept from Denmark

The vessel’s main dimensions have been optimised for calling in Bangkok, but the design features are said to offer benefits on any route. The hull design and propulsion configuration together are claimed to offer fuel economy some 15%-25% per TEU better than equivalent existing vessels, with reduced environmental impact, less water ballast, slow-steaming potential,flexible transit speeds, loading flexibility and a high container capacity for its size, including higher than usual reefer capacity.

The key to the increased propulsion efficiency is said to be the use of an electrically driven counter rotating ABB Azipod unit, which also enhances manoeuvrability. The ship makes us of ABB’s onboard DC grid system. Total capacity is 2,116TEU

The counter rotating ABB Azipod is fitted behind the directly driven main propeller. The power balance between the main propeller and the Azipod is approximately 65/35 %, and as the Azipod is fully azimuthing, the vessel will have a high level of manoeuvrability, to reduce the need for tug assistance. Compared to a vessel with a conventional diesel-direct propulsion system the main engine can be considerably smaller, and with a correspondingly smaller propeller diameter in combination with a low shaft line, ballast water to submerge the propellers in light loaded conditions is said to be generally not necessary. At 18 knots the main engine, equipped with a shaft generator, will deliver the entire propulsion power including the electrical power for the Azipod unit, the hotel load and the reefer containers. Additional auxiliary power is only necessary if higher speeds (up to 21 knots) are required or if an exceptionally large number of reefer containers are carried.

Three auxiliary engines with a total electrical power output of about 8,000kW are arranged in an auxiliary engine room, which is completely segregated from the main engine room. With the main engine stopped, the vessel is able to navigate with a speed of more than 13 knots on auxiliary power and the Azipod alone, which provides redundancy and ‘return to port’ capability.

The ABB onboard DC grid system enables the engines to run at optimal load at any cruising speed from 2 to 21 knots, enhancing fuel economy and providing the option of highly flexible transit speeds, including slow steaming, which is not the case for the majority of feeder vessels of today.

With an overall length of 172m, beam of 30m, at the Bangkok-max draught of 8.2m deadweight is 18,300dwt, rising to about 28,400dwt at the fully loaded draught of 10.5 m. The narrow deckhouse is positioned midships to provide significantly better vision from the bridge and to allow some 15 % more containers to be carried on deck than on conventional feeder vessels with aft deckhouse. The midships location is said to offer better crew comfort in bad weather than with a forward deckhouse.

With HFO tanks in a simple, square block below the deckhouse, trim compensating ballast water and changes of trim during a voyage are less necessary. Additionally, the tanks are segregated from the sides and the bottom in preparation for Clean Design class notation.

Space in the engine casing will allow fitting of scrubbers or a SCR system so that the vessel can be adapted for navigating in ECAs, while provision for containers holding batteries on the aft deck, which can be connected to the DC grid, means the ship can operate in zero-emission port mode if needed.

Five tiers of high-cube containers can be stacked in the holds and six on the hatches. In the gearless version the vessel will carry up to 1,448TEU on deck and 668TEU in the holds corresponding to a total high-cube capacity of 2,116TEU. As designed, the reefer capacity below deck is 438TEU.

Maersk Broker was also involved in the design, and the company says it is taking on the role as exclusive broker for this containership design. Maersk says that compared to the many traditional designs on the market today, the development of this design has been characterised by real innovative ‘thinking outside the box’, which has produced good results on speed/consumption, stowage flexibility, and transit speed flexibility. The broker believes the concept to be future-proof design, and potentially attractive to both liner operators and tramp owners, who are focused on stowage/speed flexibility and fuel efficiency – and thus a greener profile.