An Articulating Hinge for a 50,000-TEU Container Ship

The recent forecast by McKinsey Consulting Group that container ships could eventually reach 50,000-TEUs capacity has prompted some technical evaluation of the concept. One possible option could involve the installation of an articulating hinge.

A long-term evolving trend has occurred in the container ship transportation sector and prompted by increased trade among distant nations. The size and capacity of container ships has steadily increased over the years from 800-TEUs during the late 1950’s to the present 22,000-TEUs vessels that have recently entered service. Some maritime researchers have identified numerous constraints that could delay the development of larger, higher capacity container ships. However, developments are underway that could pave the way for the introduction of a small number of slightly wider (66.5 meters), deeper (18 meters draft), higher (83 meters, 65 meters above water) and longer ships (450 meters).

Evolving Developments

The Suez Canal expansion involves parallel northbound and southbound channels that could allow for larger vessels being able to transit between Gulf of Suez and Mediterranean Sea. The future prospect of competition from a seasonal navigable arctic passage for mega-size ships could encourage the Suez Canal Authority to consider increasing the submerged vessel cross-section from the present 1,006m2 to 1,200m2 (18-meter draft x 66.5-meter beam). Deep water terminals are under development in Southern India (Vizhinjam, Kerala), Eastern Canada (Melford, Nova Scotia) and Southern USA (LIGTT – Louisiana International Gulf Transfer Terminal) that will all provide 18-meter draft.

The larger ship could theoretically carry 28,000-TEUs and sail between Southern India and North America. There may be scope for innovative developments in crane technology to accommodate the additional 10 meter height by 7.5 meter width of the larger vessel. Suitable container transshipment terminals are still being developed in Southern India and North America, allowing scope to dredge the port of Vizhinjam to 20 meters and develop crane technology to serve larger ships that would sail between these future companion ports that connect to numerous other ports in their respective regions. Suez Canal Authority would decide the future of this possibility.

Available Companion Ports

The Port of Vizhinjam would serve as the transshipment terminal for smaller ships that connect to ports elsewhere around India, Bangladesh, Myanmar, Western Thailand, Western Malaysia, Western Indonesia and Western Australia. Melford Terminal in Nova Scotia in Eastern Canada would connect to ports located along the American east coast as well as along the St Lawrence River and Seaway, extending to the Great Lakes. In the Southern U.S., Louisiana International Gulf Transfer would connect to the American inland waterway system as well as to ports in Western Florida, Texas, Eastern Mexico, several Caribbean ports.

The possible future volume of container shipment business that could move between the Southern Indian and transshipment terminals in Eastern Canada could warrant the development of five-mega-size ships that would sail at 19 knots over the 7,700 nautical mile distance within 17 days on weekly departures. Mega-ships sailing at just over 20 knots between Southern India and the Southern U.S. (LIGTT) could cover the 9,720 nautical mile distance within 20 days, allowing a fleet of six vessels to provide weekly departures including a 24-hour layover at LIGTT.

The Articulated Ship Option

While lengthening ships incurs greater structural stresses on the hull, the installation of articulation couplings between short sections of ship promises to reduce structural stresses on extended-length ships. American designers have offered designs of articulated ship that include a single coupling and also multiple couplings. The design of the articulation coupling could provide both relative vertical movement and relative roll between a 350-meter forward section and 200-meter rear section. Computer controlled bow thruster and side thruster placed near the coupling would assist stern rudder and stern propeller to maintain directional control.

The American Sea Snake design involves a multi-section, ocean capable concept ship with couplings designed to allow relative roll among up to five sections of 150 meters to 200 meters each. Either concept ship could be built to the 15.5-meter draft and 59-meter beam of the largest present day container mega-ships, with potential for 18-meter draft by 66.5-meter beam if the Suez Canal Authority were willing. While a two-section ship could be built to 500-meter to 550-meter length (35,000 TEUs), a multi-section concept could be built to 600-meter to 1,000-meter length (50,000 TEUs) when assembled in preparation for departure.

Articulated Ship Development

Present day articulated and integrated tug barges that sail along inland waterways and also ocean coastal service could serve as the basis for future articulated ship development. The concept of the two-section coupled ship involving a longer forward section and shorter trailing section originated at the University of Michigan and intended for future service on the Upper Great Lakes. A two-section concept ship could be developed from older ships and placed into domestic container transportation service between an east coast Canadian transshipment terminal and Montreal, for sailing across the Gulf of St Lawrence and Lower St Lawrence River.

Following some refinement and upgrading, it could subsequently be re-assigned to sail through rougher seas located between the same transshipment terminal and an east coast American port. It would become the basis upon which to develop a much larger trans-oceanic two-section ship. The development of multi-section ships would be based on precedents developed of tug barges and a two-section ship. Several years ago, European researchers suggested the development of articulated/coupled ships for service through the comparatively shallow draft along Russian side of the Arctic, on voyages between Eastern Asian and Western European ports. 

Trans-Arctic Transport

While small container ships have sailed through the Russian side of the Arctic region, sailing conditions dictate a relative narrow and shallow vessel built with the draft and beam of Seaway-max ships. Reinforced ships’ hulls would be essential to contend with Arctic Ocean conditions at the beginning and end of the navigation season. An extended length version of the ship would greatly increase carrying capacity, offer greater versatility in terms of propulsion and incur improved transportation economics. The Sea Snake design could serve as the basis by which to couple five 150-meter sections into a commercial vessel.
 
The design could incorporate retractable propulsion units such as forward azipods or counter-rotating Voith-Schneider vertical-axis propulsion technology installed near the structurally reinforced ice-breaker bow. Extended vessel length would allow for multiple (retractable) propellers that could be deployed to increase low-speed propulsive thrust to push through snow and ice. Such vessels could to Western European ports and if the Canadian side of the Arctic remains closed to commercial shipping, such vessels could sail from Eastern Asia via the Russian Arctic and through Denmark Strait to the St Lawrence River and Montreal, with tugs pushing sections of vessel to upstream ports.

Conclusions

The increasing demand for greater carrying capacity aboard container ships could lead to the development of articulated ocean going ships. Articulated tug-barge vessels that carry bulk freight are already operating in American coastal service.

Research and design has already been undertaken on possible workable designs of future coupled ships. The Russian side of the Arctic represents a market for articulated, extended length coupled ship technology. South Korean or Japanese ship yards may be interested in developing such technology for Chinese – European trade that sails via the Russian Arctic.

There is scope to build larger single-unit container ships of up to 28,000 TEUs that could become available after the twinning of the Suez Canal. The design could form the basis of extended length articulated versions. Terminals able to accommodate the 18-meter draft of such ships are under development in Southern India, Southern U.S. and Eastern Canada.