Danish naval architect company KNUD E. HANSEN has revealed three new container feeder vessel designs it has been working on over the recent period.
The first in the series of three designs relates to a 2,000 TEU vessel that was conceived of to specialise in calling at small, narrow, up-river ports, for example the Port of Bangkok, Thailand. Navigating such harbours requires a vessel to have a shallow draught and as a result the vessel is required to have a relatively small diameter propeller.
To cater for this without a loss of power, KNUD E. HANSEN’s designers introduced a special propeller arrangement employing a directly driven main propeller with a diameter of 5.8 m and a counter-rotating Azipod with a 4.7 m propeller.
“The dual arrangement makes up for the relative small diameter of the propellers. The total propeller disk area of the two propellers corresponds to the area of a single propeller with a diameter of approx. 7.4 m and further, the counter-rotating propeller will recover some of the swirl energy produced by the main propeller, which increases the overall efficiency,” explains Jesper Kanstrup, Senior Naval Architect at KNUD E. HANSEN.
A second design foresees a vessel of a 3,800 TEU capacity, fitted out with a larger diameter and a slower-turning propeller that allows for a propulsion efficiency.
The deckhouse of this vessel is positioned slightly forward of amidships to maximize the number of container slots on deck, making the vessel LNG-ready.
“Here, we have a square block below the deckhouse, in which we can either have HFO tanks or LNG tanks. What’s more, the vessel can be built with HFO tanks and easily retrofitted for LNG the day the infrastructure for LNG is sufficiently developed if a dual-fuel engine is installed in the first place.”
The sketch below shows how the vessel can be converted.
The design is being developed in consultation with DNVGL with the aim to achieve an Approval in Principle in order to enable the design easier to market.
The third arrangement sees the application of an innovative hull shape suited for carriage of both partial and full container loads.
The solution proposed by KNUD E. HANSEN is that instead of a conventional hull (sketch A below) you take a hull with inclined sides (B), but mirror the triangular sections in each side (C) to create a trimaran or in better words a “stabilized mono-hull” with a narrow main hull with vertical sides and outrigger hulls with a triangular cross section, but vertical sides towards the quay (D).
This way you have the narrowness associated with low accelerations at partial load, and with the triangular section of the outrigger hulls, increased stability for full loads at deeper draught.
The design features an open top section in the main hull, with 40ft containers stacked in a fixed cell guide system. Because cell guides are not fitted outboard the main hull above the outriggers, the loading flexibility with regard to carrying 20, 45 and 48ft containers has been addressed.
“Many have proposed an open top container vessel, but to prevent water from being shipped over the sides of the vessel and into the open holds when the vessel is rolling in bad weather, the hull depth must be very high. And with a deep hull, the handling time for the containers will be increased because of the increased vertical travelling distance.”
Because the main hull is narrow, the sides of the open-top holds can be lower, and with lower sides, faster container handling.
When the vessel is not heeling, the sides barely touch the surface of the water, meaning little resistance. According to the designer, as a result, the vessels can have a relatively high service speed while maintaining a reasonable fuel consumption per container, per nautical mile.
Image&Video Courtesy: Knud E. Hansen