Germanischer Lloyd (GL) gathered a group of clients together in Hamburg for a Forum to examine the latest developments in container stowage and transport. The Forum, one of many held by GL on a regular basis around the world, looked at how, in a time where the market is especially tight, added flexibility in container stowage could help to keep operators competitive.

Throughout the maritime industry there is an increasing recognition that “off the rack”, whether in ship design and operation or the management of a fleet, is no longer the only option. Being able to tailor individual vessels and plans to optimise their flexibility is essential to continuing profitability. Through the presentations and discussion at the Forum, GL showed the attendees how with GL they could re-examine standard practices and maximise their ability to respond to the demands of the market.

More than 50 representatives from the container industry met with GL experts at the Container Ship Forum, to hear several presentations and participate in the ensuing discussion session. The speakers were introduced by GL’s Hans-Günther Albers, who introduced the themes for the event and Jan-Olaf Probst, GL’s Executive Vice President and Global Ship Type Director, moderated the Forum and led the discussion round.

GL was the first classification society to introduce rules for container stowage and lashing, noted Holger Jefferies, GL’s Head of Research & Rule Development – recently returned from some 8 years in Shanghai. Those rules have been continually updated since their introduction, most recently in 2012, and are the subject of a yearly examination by a technical committee. Mr Jeffries laid out some of the relevant rules, both from GL and international organisations, and looked to the current challenges for the container industry. Over capacity, high fuel prices, and the cascading effect of extremely large vessels entering the market, meant that ensuring maximizing capacity while maintaining loading flexibility, were essential to staying competitive.

Castle-, or blind sector-, stowage is a method of utilizing permitted blind sectors in the navigational field of vision for extra storage. The regulatory picture at an international level was vague and uneven and the ramifications of using the technique in terms of its acceptance from port state control administrations also unclear, said Michael Oberländer, from GL’s Department of Safety and Stability. A growing trend in Asian markets, the discussion at the Forum was an ideal way to gauge the interest of the attendees in the practice. An interesting exchange occurred with both GL experts and the industry invitees emphasising the importance of safety in navigation and offering several suggestions for the development of the field of vision, including the more widespread use of cameras.

The presentations at the Forum were designed to link together, emphasising the search for flexibility in stowage while ensuring safety levels based on a sound technical basis. Helge Rathje, from GL’s Department of Rule Development, looked at wind loads on stacked containers and how an analysis of these loads might enable more flexible stowage and higher intake levels for operators if the area as well as season will be considered. Mr Rathje set out the conditions for GL’s review of its rule loads on 40’ unshielded containers and the wind loads based on 30 and 40m/s wind speed acting on 7 and 8 container high stacks at 0 and 18 degrees roll, carried on a 48.2m wide vessel. Computational fluid dynamic (CFD) analysis revealed the GL’s wind loads corresponded to speeds of 121 km/h, equivalent to 12 on the Beaufort scale. Notably, Mr Rathje demonstrated that the rule loads were realistic, but were for containers on the recessed top tiers somewhat high. This suggested the potential for tailoring stowage plans to the route and wind conditions faced by individual vessels.

In his second presentation Mr Rathje elaborated on the idea of route specific lashing of containers. By examining the wave loads of a typical Asia to Europe route for a megaboxer vessel, Mr Rathje showed how a departure from the rule load for unrestricted service could allow for not only more flexible weight distribution, but the potential addition of a 10th tier. This could result in an additional nominal 182 FEU on 14 bays aft of accommodation or an additional nominal 338 TEU and nominal 13 FEU aft of accommodation, while also resulting in better weight distribution in the container stack itself. Another option is a better weight distribution in the container stack itself, which could result in a larger number of loadable containers and reduce the number of empty containers.

Both after the presentation and in the discussion period the idea of route specific trade yield and container lashing and storage provoked a great deal of interest and a spirited discussion between the attendees and GL experts. GL is currently considering the development of class notations for route dependent container lashing and storage, with the possibility that in the future lashing might also be adapted to reflect route and season. Having a second load plan on board would not prevent operators from reverting to the standard plan if the circumstances so required, but would allow additional flexibility when the opportunity presented.

A spate of container lock failures in 2005 and 2006 led experts at GL to launch an ongoing investigation of the causes of such incidents. The investigation resulted in the development of the first ever guideline for the testing procedure of fully automatic locks (FALs). Daniel Abt from GL’s Department of Loading Gear and Outfitting presented the results of GL’s analysis, which included the first finite element analysis of the locks’ bearing capacity. GL has also been carrying out tests to validate the results, he said, which had resulted in the new test procedure for FALs – published in the latest edition of the GL Rules. Mr Abt also showed how function testing of FALs took place on a single Drehtainer jig to insure consistency.

To end the presentations, GL’s Viktor Wolf, examined the growing use of flexitanks in sea transport. Flexitanks are flexible plastic tanks designed to enable the transport of bulk liquids inside standard 20ft containers. Both the number of flexitank movements and the filling levels of those tanks were increasing, he said. In the absence of permissible filling criteria, there was potential for damage not only to the container enclosing the flexitank but the goods transported alongside. Buckling of the side wall of the enclosing container could result in the collapse of stacked containers, due to the weakening if the container frame. Mr Wolf set out GL’s calculations for the maximum permissible loads based on the positioning of the container on board and the length of the vessel. The results indicated that, even in the best case scenarios, filling levels have to be considered carefully.