Propulsion Options for Ultra Large Container Ships

Lloyd's Register (LR) has completed a study to find the optimum solution to the question that no-one else has yet answered - how to propel the next generation ultra large container ship (ULCS). A joint investigation by LR and shipping economists Ocean Shipping Consultants (OSC) found that the optimum ULCS that can potentially be supported by the current and forecast global container trade and ports network is a 12,500 teu vessel. This investigation, started in mid-1999, aimed to identify the potential for even bigger vessels and subsequently determine possible structural problems that might be encountered.

Leading on from this study, Lloyd's Register developed a concept design for the ULCS, looking at structural and performance aspects; midship scantlings were developed and hull girder bending and torsional response considered, together with maneuverability aspects. The result was that there are no insurmountable technical challenges perceived for a vessel of this size, with one exception…how do you propel the ULCS?

Lloyd's Register launched another ULCS study to solve this problem. Results show that a single screw 12,500 teu ULCS can achieve about 23.5 knots, but for ships over 10,000 teu, it would be necessary to go to twin screw if 25 knots service speed is required. But there is a penalty in going to twin screw - although the ship's productivity increases, so does the capital cost, the fuel consumption and the daily operating costs increase. Further study concludes that it is clear that 12,500 teu vessels offer marginal savings at 25 knots but very significant potential savings at 23 knots, representing a valid option for the very highest volume operators.

David Tozer, container ship segment manager at Lloyd's Register said "The container shipping industry may well be looking, within the next five to ten years, for ships with a capacity of around 12,500 teu - the ULCS. It is only a matter of time before such ships are built."