The ULCS study, started by LR in 1999, found that the optimum size is 12,500 teu. The latest phase addresses the question that no-one else has yet answered – how to propel the next generation ultra large container ship (ULCS).The ULCS concept

A joint investigation by Lloyd’s Register (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 initial study, Lloyd's Register developed a concept design for the ULCS, looking at structural and performance aspects; hull bending and torsional response considered, together with manoeuvrability aspects. The results, published in March 2000, concluded that there are no insurmountable technical challenges perceived for a vessel of this size, with one exception…how do you propel the ULCS?

How do you propel the ULCS?

Lloyd's Register has pioneered the ULCS initiative from day one, and continues to do so. It launched the second phase of the study, to solve the problem of how to propel the ULCS, in late 2000. To arrive at the solution LR carried out a series of propulsion calculations covering a range of ships from 4,000 to 12,500 teu capacity, at a number of speeds. The power required to propel each of these design options was derived and detailed propeller calculations were carried out to examine such limiting factors as cavitation and propeller-hull interaction vibration.

The 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. The chart overleaf, developed by LR, shows the various power requirements for a range of container ships, including the ULCS. The break in the two upper lines illustrates the limits of single screw propulsion for these leviathans.
Power requirement for the ULCS - Economic Analysis

The results from the detailed propulsion study were then fed into a major economic analysis, and a series of voyage and service cost analyses was developed to identify the vessel costs associated with shipping containers on the principal trades.

The results showed that there is a penalty in going to twin screw – although the ship's productivity increases, so does the capital cost, fuel consumption and daily operating costs. Further study concludes that 12,500 teu vessels potentially offer marginal savings at 25 knots but very significant savings at 23 knots – offering a cost saving of more than 19% over a 8,700 teu vessel at 25 knots – representing a valid option for the very highest volume operators.