Approaching Limits in Ship Size Development

The shipping industry is slowly approaching limits in ship size development, DNV GL Business Director Jost Bergmann said while speaking at DNV GL’s latest Container Ship Forum and Bulk Carrier Forum in Hamburg.

The forums looked at a broad spectrum of topics including environmental regulations, trends in ship design as well as the new DNV GL rule set, attracting some 150 representatives from the container and bulk industry.

In the near future it would be possible to build ultra-large containerships with a capacity of 24,000 TEU. Based on a current 19,000 TEU vessel design, these ships could be one hold longer, two rows wider, and one hold tier higher, Bergmann added.

“Due to stability factors and steel thickness requirements, it is easier to increase the beam than to increase the length. But besides coping with higher acceleration and gravitational forces, ultra-large wide-beam vessels would also be constrained by port and seaways limitations, such as crane outreach and drafts,” he went on to say.

According to Bergmann, in the Suez Canal, for example, restrictions for the ship’s cross-sectional area are leading to a permissible draft of only 15 meter for a 65 meter beam. This may be an acceptable design draft, Bergmann explained, but the scantling draft would be higher. Further height constraints could apply due to bridges in ports such as Hong Kong, Hamburg or Osaka.

Other topics covered during the forum included Route Specific Container Stowage (RSCS), overview of new low sulphur fuel products that have recently entered the market, ballast water management (BWM) and vetting schemes for dry cargo vessels.

DNV GL has also issued a new publication entitled “Sulphur Limits 2015 – Guidelines to ensure Compliance”, in which DNV GL experts provide a general overview of the regulatory background, describe potential difficulties associated with the fuel change-over procedure and discuss which technologies can best help vessels fulfil the new requirements.

It has developed a ship-specific Fuel Change-Over Calculator (FCO) to help shipowners and operators determine the ideal parameters for their vessel’s fuel change-over.

“Taking into account variables such as a vessel’s fuel system layout, any constraints on temperature and the variable sulphur content of fuels, the FCO Calculator can significantly reduce the risk of human error during the preparation of the change-over process,” says Jörg Lampe, Senior Project Engineer Risk & Safety, Systems Engineering at DNV GL.

The software uses a complex numerical simulation that is more accurate than previous linear models and delivers insight into the optimised lead time for the change-over process, its costs and the maximum hourly consumption to meet constraints.

Press Release