Larger than life
Alex Hughes explains that stowage is key to effective handling of ultra large containerships
Despite the naysayers, the deployment of ultra large containerships has not completely absorbed quayside lift capacity or kept smaller ships waiting for berths at every port capable of handling them. Indeed, according to Medcenter Container Terminal (MCT) managing director Domenico Bagala, the exact opposite may well be true.
“Mega-hub operations must never forget 'smaller' vessels. Irrespective of size, these remain part of the whole network and have to be efficiently handled, too,” he says. “However, terminal efficiency does actually increase as a consequence of better shift utilisation when handling ULCSs, since there are a lower number of vessel calls and a reduced number of manoeuvres in port.” Therefore, he argues, overall productivity rises since quay cranes don't have to be moved quite so often, leaving more than sufficient capacity in the system to also handle smaller ships.
However, he concedes that the potential is still there for bottlenecks to occur when handling these larger ladies. Indeed, Mr Bagala suggests that ensuring a constant flow of boxes between the quay and the yard is crucial to efficiently manage really large volume exchanges.
“At MCT, where the majority of traffic is both in the form of transhipment between deep sea and feeder vessels, and also relay between main strings interchanging volumes, berthing plan arrangements are crucial if the terminal is to operate efficiently. To achieve this, we prefer to use, where possible, a fixed berth scheme by service,” he says. “Furthermore, information accuracy and the reliability of nominated transhipment connections is crucial to ensure the correct and efficient management of yard-side tasks.”
In the Middle East, Angelo de Jong, procurement manager at Khalifa Port Container Terminal (KPCT) is convinced that, while a role still exists for smaller vessels, the future lays with ULCSs.
Although smaller vessels can invariably be turned around much faster, on a cost per teu basis it's proven that larger vessels give much higher benefits, despite the fact that they are in port for much longer periods of time, he says. In addition, customers save berthing time. So, even though it might be faster to turn around two smaller container vessels with a combined box exchange equal to that of a much larger vessel, both fuel consumption per teu and even the running cost of the vessel itself remain so much more competitive on larger vessels.
But in terms of overall productivity, there are still arguments to be made for and against larger ships.
“It's generally agreed that deploying eight gantry cranes is the limit in terms of current vessel size. Berth productivity in these types of situation is high, simply because you have more cranes. However, subject to the actual crane split, moves-per-hour for individual cranes are likely to be lower, because it's so congested underneath the cranes; a tunnel effect is basically created as ground transport cannot easily exit from beneath the cranes. Clearly, on smaller vessels, using fewer cranes, crane production could be higher,” says Mr de Jong.
Nevertheless, there are many variables that determine berth production, the most important of which is stowage. Other key variables are the ability of the yard to keep a continuous flow of boxes to and from the stacking yard and determining how many straddle carriers, terminal tractors or RTGs are deployed.
“The amount of equipment that you dedicate has a really big impact,” he says. With so many variables, Mr de Jong cannot give a definitive answer to the question of whether productivity is better or worse with ULCSs than with smaller vessels.
Significantly, the use of ULCSs may well drive more automation if the experience of the semi-automated nature of KPCT's operations are anything to go by.
“The reduced dependency on manual operation at KPCT has boosted productivity, while distances between the quay and the stacking yard are also much shorter compared to an RTG terminal. The fact we use straddle carriers - which decouple the crane from the ground transport system - also helps to cut out the need for trucks to queue to either pick up or offload containers. When a terminal relies on terminal tractors, cranes may have to wait for containers to arrive, whereas in our terminal, if no straddle carrier is available, the crane can simply put the box on the ground and then continue operating. So, we can handle very large ships at around 40 moves per hour using five or six cranes, which is quite good,” says Mr de Jong.
He points out that this is ultimately driven by the ability of the yard to keep up with the required supply of boxes, something which is helped by the fact that the stacking area has been designed to generate short cycle times, given the close proximity of the yard to the quay.
Meanwhile, neither Mr Bagala nor Mr de Jong are concerned by the inevitable longer cycle times implied by using the longer outreach cranes required by ULCSs. Mr Bagala, for example, points out that the technological solutions offered by manufacturers and the very high performance achievable by the latest generation of gantry cranes - combined with the ability of skilled drivers - easily offset the longer travel distances required to operate on ULCSs.
Mr de Jong adds that longer cycle times are a fact of life and that while productivity could fall, there are fixes.
“At Khalifa, on future cranes, we are aiming to increase the speed and acceleration of the trolley and hoist to counter this. Although it will help, it is not the ultimate solution. If shipping lines do want to ensure maximum productivity and the shortest possible turnaround times, they will have to optimise their stowage, because this ultimately dictates whether you have short cycle times or long ones,” he says.
As an example, he cites an operation concentrated on emptying the centre hatch, where there would be containers on both the port and starboard side of the ship, forcing the crane operator to dig down into the centre.
“This means having to hoist all the way up and trolley down. In that type of stowage, there can be a tremendous impact on production,” says Mr de Jong.
Worse still, the overall height of the largest gantry means that the operator is often seated 50 metres above the vessels he is working. In most cases, there will be no visual aids or cameras, making operations a real challenge and a real driver for automation.
“There is a clear limit to manual operation, so bigger ships could be said to be driving automation of quay cranes. There is a compelling financial argument, too,” he says, noting that cost per teu declines as vessel size grows.
Looking for the containership size ceiling
Can terminals continue to accommodate ever larger ULCSs? MCT's Domenico Bagala suggests that there could very well be a financial challenge, since huge investment would be required to adjust the infrastructure and equipment that is currently being designed to operate on vessels with an upper limit of 20,000 teu.
KPCT's Angelo de Jong notes that in the 1980s and 1990s it was said that there would be an upper limit to the size of both vessels and cranes; in spite of this, both have increased in size.
“People are again questioning whether we haven't reached that upper limit, but we still cannot say with any certainty that vessel sizes will not continue to grow. In fact, I believe we will see longer, wider and taller vessels,” says Mr de Jong, who is a naval architect by profession.
He points out that projected 23,000 teu vessels will be over 50 metres longer than the biggest ships today and have 25 rows of deck-stowed containers. Nevertheless, he points out that the number of containers that can be stacked does have a practical limit.
“Go any higher than eight, nine or ten containers and the stack will eventually collapse. There is also a restriction on the strength of the vessel given high degrees of torquing and large bending moments. As a result, I estimate that ULCSs will not exceed 500 metres in length, because it would be difficult to make them strong enough. However, people have said that before…”
He also recalls that, in the mid-1990s, VLCCs and bulk carriers grew enormously, sometimes up to 700,000 dwt, but then began shrinking again, prompting him to suggest that maybe ULCSs will, indeed, eventually hit a ceiling.
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