Factors affecting future container liner dimensions
N our November 2005 issue, we reported on the planned new design for a twin-screw 13,000TEU container liner conceived by Hyundai Heavy Industries in conjunction with class society Germanischer Lloyd. Some of the important influences on the determining features of this mammoth - which could probably offer transport costs reductions over smaller designs of around 13% - and the likely advances ahead were revealed by GL in Hamburg at the end of November. Jan-Olof Probst, manager for the container sector, gave a timely reminder, for those who had forgotten, of the very large percentage of containers that today are carried on deck - around 50%. This compares with only 35% on the high-sided liners of the early 1970s when the same figure was 35%, and has been made possible only by a wider mid-body and broader fore and aft sections.
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It is interesting to record that today, post- Panamax liners are able to dispense with most ballast water in the fully loaded condition - many smaller vessels still have to sail with up to 10,000tonnes of ballast to ensure sufficient stability. At the same time, an 8000TEU (post- Panamax) ship can actually only carry around 6000TEU if they are all loaded to the industry- average 14tonnes weight. GL's largest vessel in service is MSC Pamela, first of nine 9200TEU liners ordered by German owner Claus-Peter Offen from the Samsung yard in Korea; she was delivered in July 2005. A further four ships have been ordered by the Mediterranean Shipping Co (MSC), which is also today the owner of MSC Pamela. At the time of writing, this is the largest container ship ever in service; it is however interesting to record that she was originally planned to be (and ordered as) a 8200TEU design but at the end of 2003, capacity was hoisted and the hull re-modelled in anticipation of a boom in freight. Expansion was achieved by increasing the breadth from 42.80m to 45.60m, allowing for 16 rows in the holds and 18 on deck. Since the moulded depth was also increased to 27.20m, a more satisfactory hold/deck ratio was also achieved with more than 50% of the boxes now stowed in the holds - in 10 tiers, with a further seven on deck. Sockets are provided for 700FEU boxes.
Important influences on future container designs will be the introduction by August 1, 2007 of mandatory positioning of fuel tanks inside double skins (already being achieved by some owners by placing most of these tanks transversely between holds), and an expectation by GL that average container weight will grow. Forward-thinking owners are already building in design margins so that a maximum 15.00m scantling draught can be maintained. As revealed on the GL/Hyundai 13,000TEU proposal, the wheelhouse and accommodation block is most likely to be placed well forward. From a naval architect's perspective, this is good news, since it will help to restrict hull
THE NAVALARCHITECT FEBRUARY 2006
The largest yet:MSC Pamela, capable of loading around 9200TEU/9500TEU and the first of a series of 13, was completed last year by Samsung for Mediterranean Shipping Co. When the next jump is made to 12,000TEU or 13,000TEU, it is likely that the deckhouse will be shifted forward, and twin propellers will be specified.
Proposed cross-section of a GL-classed 12,500TEU twin-screw container ship, with a breadth of 54.20m but still with a scantling draught of 15.00m, as on a 9500TEU ship.
deflections and limit stress. Navigating officers will also have a much improved forward view. Some questions have been raised over the positioning of the main fuel tanks under this deckhouse but since any fuel there is unlikely to be heated to any great degree, the risk of fire is minimal. GL believes that this ship concept could be expanded to accommodate 15,000TEU, if an owner required such a figure. Although a single main engine and propeller are in theory perfectly possible for giants of this size, draught restrictions might make such a propeller less desirable. A most interesting alternative could be the
ABB/Samsung proposal of a single main engine and propeller
supported by an electrically driven Azipod behind (The Naval Architect October 2001, page 6), however, quite of lot of extra cost would probably be involved. Twin screws - as Hyundai proposes - represent a good, well proven compromise, providing a high degree of redundancy. The Naval Architect is additionally informed that large engine builders, such as Hyundai, which have tooled up their works for a maximum diesel engine bore of 980mm, are not very interested in investing in additional equipment to build only a few engines with bores beyond 1000mm. Of course, the gas turbine is still waiting in the wings!
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