Growing the ships and the fleet

New orders for ever-larger containerships look set to elevate Seaspan?s global position.

Director of Vancouver-based Seaspan Container Lines (SCL), Graham Porter, says “Among the main limiting factors in building container ships over 10,000 TEU is the thickness of the steel plate and the existing welding techniques.”

He speaks with some authority, having recently worked with his firm to place orders for five 4,250 TEU ships for delivery in 2005, five 8,100 TEU ships for delivery in 2004, and eight 9,600 TEU ships for delivery in 2006/2007 on behalf of Seaspan and its partners China Shipping and Danaos Shipping of Greece. These ships will join five 4,250 TEU ships that Seaspan took delivery of in 2002. All of these ships will go under charter to China Shipping Lines. Seaspan also has on order nine 4,250 TEU ships for delivery in 2006 and ?07 with charter arrangements in place for CP Ships.

When delivered, these ships will catapult SCL into the major league of container ship owners. “We have great confidence in the people at Samsung Heavy Industries in Korea. Of their approximately 10,000 employees something like 2,000 are engineers/naval architects. Their engineering and design capabilities are superb,” explains Porter.

Recognised as world leaders in the building of container ships, there is little doubt that when ships with larger than 10,000 TEU capacities are ordered, they will be built in Korea. But, as Porter explains, they will be built with significantly different technologies. The 9,600 TEU ships currently on order have grown within the same technological envelop as that developed for the 8,100 TEU ships. “With some more tweaking of the design, we could take it to 10,000 but that will be the limit of the current 90 mm hull plating and engine sizes,” he says. “To go larger than that would require heavier framing and plate which, by weight alone, would cancel out the increased cargo capacity.”

Porter sees a continuing role for the 4,250 TEU ships in dedicated runs between smaller ports such as Pusan Korea to Vancouver B.C. They can also transit the Panama Canal to take cargo from Asia and deliver by the all-water route to various ports on the US east coast. He calls these the 737s of the shipping industry in reference to that work horse of the airline feeder routes. He explains that the challenge for many shipping lines that took delivery of larger Panamax 5,500 TEU ships in the late 1990s, will be that these ships had very large capital costs that will continue to bear on their operating costs. “The capital cost of our 8,100 TEUs are about $80 million each, but a 5,500 ordered in the late 1990s would have a similar cost of about $70 million,” adds Porter. That means that larger vessels can take on a short cargo for a back haul across the Pacific to Asia and transport it with no loss. They are then in position to take full loads from Asia to America at competitive prices while maintaining profitability.

Container cranes

With most major ports installing container cranes that will reach to 20 or even 22 containers stowed across a ship, the beam stacking of containers is not an issue. A 4,200 TEU ship has a length of 259.8 metres and a beam of 32.25 metres with 14 rows of containers across. The 8,100 TEU ships have a length of 334 metres and a beam of 42.8 metres supporting 17 rows of containers across. The 9,600 TEU ships will be just slightly longer at 337 metres but their beam is increased to 45.6 metres permitting them to take 18 rows of containers across. Porter understands that the big ship?s design will allow for the addition of another 80 feet of length and still accommodate the resulting torsional forces in order to take two more container bays and bring the total capacity to about 10,200 TEU.

These ships are the 747-400s of the marine world taking on huge cargoes between ports such as Shanghai and Long Beach or East Asia and Northern Europe. While the container trade is growing only marginally, the efficiencies of the larger ships will allow them to compete effectively on the heavier-volume cargo routes.

When China Shipping began developing its new facility in Los Angeles, the port worked with both the shipping line and Samsung to design the port modifications to meet the requirements for depth alongside to accommodate a 13-metre loaded draught and turning basins of the new larger ships.

Both the 8,100 and 9,600 TEU ships will use the same MAN B&W 12 cylinder 68,520kW main engines but the extra beam will cost the larger ship about one knot in speed off the 8,100 TEU ship?s 25.2 knots. The 4,250 TEU ships use MAN B&W 8-cylinder 36,502kW49,680 HP engines and single 1,600kW bow thrusters. Both the larger vessels will have single 3,000kW bow thrusters. Porter says that the growth in ship size involves two related factors ? the hull form and the propulsion package. Some speculation on container ships larger than 10,000 TEUs predicts twin-engine configurations to drive the larger ships. It is such thinking that holds Seaspan back from committing to those ships. “We felt safe with the hull designs at 9,600 TEUs and we could use the same proven engine, but going up in engine size from that brings on some less proven technology and greater potential problems,” he explained.

The effect of the increased beam on the ship?s GM is of considerable significance for sea keeping and cargo safety. The big 42.8 and 45.6-metre beams and greater lift on the bilge chine on the post Panamax 8,100 and 9,600 TEU ships will cause a faster roll. This will, in turn, add to the stress on the container lashings and the container stow itself. “We are working with the people at MacGREGOR, to develop lashing systems that will handle this motion,” says Porter.

He says that on the smaller 4,250 TEU ships, they try to get heavier containers lower in the hold to reduce the rolling arc, but on these larger ships they will want some weight up higher in the stack to shift the GM and slow the shorter snappier roll. This brings him to a concern regarding the disconnect between the agents, trucks, container cranes and the ship in tracking the weight of individual containers. “We don?t know what the deadweight of a cargo is until we see our marks after the ship is loaded. Even then the crew may not know where the heavies are to add lashings. This remains a concern. There is no lack of technology to address this tracking interface, but there is a lack of will on the part of some people in the chain,” he says.

On larger ships, the location of the heavy containers will matter for the proper cargo care. But the number of heavies is not a concern as the ship?s deadweight on Ts for the 8,100s is 99,500 tonnes and for the 9,600s it will be 102,200. This exceeds the maximum potential even if each of the containers loaded aboard was of maximum weight since the volume of these huge ships prevents them from getting down on their marks. All of which brings one back to Porter?s confidence in the design and engineering expertise of Samsung. Whether the market demands will be there for this tonnage as it comes into service over the next few years is less predictable.

seaspan 10,000TEU container vessel

Length o.a./b.p. 350.0/319.0 m

Breadth moulded 45.6m

Depth moulded 27.2m

Draught, designed/scantling 13.0/14.5m

Deadweight on Td abt. 83,700 tonnes

Deadweight on Ts abt. 102,200 tonnes

Service Speed abt. 25.1 kn

(at 90% MCR with 15% sea margin at design draught)

Air draught 62.0 m

MAIN ENGINE

MAN B&W 12K98MC-C

MCR 68,520kW/ 104RPM

Fixed-pitch propeller 6 blades

Bow thruster CPP 1 X 3,000kW