CONTAINERSHIPS


was attended by a most useful number of delegates from leading Japanese and South Korean companies, it was disappointing to note that none from that country most likely to be building such giants in the future – mainland China – was represented. Emma Maersk – the newly completed and


largest container liner yet built (by the Odense Steel Shipyard, in Denmark) with a nominal 11,000TEU but probably capable of carrying more – featured in several papers. A trio of authors from ABS, the society that classed Emma Maersk, discussed some of the technical challenges that arose with hulls of this size and similar designs, pointing out along the way that the enlarged Panama Canal will enable ships up to 48.80m wide (and 366m length) to navigate that waterway. This could give rise to a new breed of vessel. Interestingly, Emma Maersk, when she called at Felixstowe on her maiden voyage, was moored in only 45 minutes compared with an anticipated 1.5 hours.


New breed large hulls Meanwhile, Jan-Olaf Probst, Germanischer Lloyd’s containership expert, gave an interesting exposé on the proposed 13,400TEU design, conceived jointly with Hyundai Heavy Industries (The Naval Architect November 2005, page 4). More than one author noted that these new very large breeds of hull (397m x 56m for Emma Maersk) meant that the lessons of the late 1960s/early 1970s, when the prototype epoch-making cellular container fleet was being created, are having to be re-learned. Such ships included Sea-Land’s 33-knot


twin-screw steam-turbine SL7 class - still in operation today with the US Military Sea Lift Command - and, although not mentioned, also Overseas Containers’ Encounter Bay class designed by Marshall Meek and his team. If the planned 18,000TEU Malaccamax ships come to pass, even more midnight oil will have to be burned. Elsewhere in this issue and on another


subject (podded propulsion, page 35), we report on the dangers of not learning from


the past when too large steps are taken too rapidly. At this conference, Jan-Olaf Probst also carefully told his audience that the container itself is actually the limiting factor on ship size; although the current test load on a standard TEU box is 96tonnes, many early weaker boxes are still in service, and it will be 10-15 years before pictures of collapsed container stacks can be eliminated. As reported in our November 2006 issue,


Japanese steelmaker Nippon Steel, in association with ClassNK, has developed a new YP47 grade of steel (47kgf/mm2


) for use


primarily in the hatch coaming structures of very large new containerships. This material, designed to overcome the loss of toughness in ever-thicker plates, was presented in an interesting paper by Y Yamaguchi and T Matsumoto, from ClassNK and H Yajima, from Nagasaki Institute of Applied Science; it discussed innovative grades designed to avoid moving beyond current thickness levels of 70mm (YP40 grade). Some graphic and startling full-scale tests


on steel plates were shown to the audience, as the high-tensile material was stressed to breaking point to develop a composition that would avoid brittle fracture, and particularly catastrophic brittle cracks. The authors noted that correct welding was a key element of YP47’s use. Mitsubishi’s Nagasaki yard is the first to apply the new steel. As important a factor to parallel hatch


coaming strength is proper design of the bow area of a large containership, and L Zhu, from Lloyd’s Register, discussed on-going work to improve structure design to avoid the continuing problems of forecastle stiffener and web buckling in heavy seas. Further examples of this unfortunate phenomenon, which once again illustrate the huge power of the sea, were revealed by the author. Some interesting work by the Finnish


consultancy Napa was discussed by C M Ridgewell, J Furustam, and A Metsä, concerning the development of a useful new technique, using well-established NAPA software, for creating a 3D model of


a containership prior to contract stage. The object is to generate a model that can be used for fast and reliable assessment of the key details needed before a contract. It is noteworthy that the method starts off


with individual containers and builds on from that point rather than using a hull structure or rough general arrangement. By starting there, many useful factors can be ascertained early on – maybe including some useful safety features for stevedores! Remarkably, Napa claims that a new design with all results can be generated within one man-day.


Reducing resistance A further evolution in the forward march of ship design was the InSAC concept of the German Friendship Systems suite, presented by Stefan Harries. This most interesting philosophy aims to reduce resistance while still increasing payload. InSAC is an acronym for ‘innovative sectional area curve’; its main feature is a delicate ‘pinching-in’ of the underwater forebody. This new hull line is already being employed on a series of 3400TEU/3700TEU ships being built by the German shipbuilder Thyssen Nordseewerke. Possibly even more evolutionary is the


inclined-keel concept proposed by three authors from the University of Newcastle. This unusual format for a large ship could, the trio claimed, allow an 11% larger propeller to be fitted; the propeller could turn at a 17.5% slower speed to give a 2% power saving, without any adverse penalties. It is indeed good news that enquiring brains are still at work around the world – partly driven today by the urgent need to contain fuel costs. We have come a long way since Malcolm McLean first launched the container revolution but by the looks of it, there is still a long way to go. Perhaps if somewhere along the line, more effort on safety could be inserted, we might reach the ultimate containership.


* Design and Operation of Containerships, held on November 22-23, 2006, in London, and organised by The Royal Institution of Naval Architects.


THE NAVAL ARCHITECT FEBRUARY 2007


59


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