The ocean carriers’ key phrase these days seems to be the cliché ‘Bigger is Better.’ The economics of carrying more containers on fewer ships regardless of the infrastructure consequences has kept ports on a seemingly never-ending path of ‘catch up.’ Port authorities and terminal operators are caught in the middle of a vise whose jaws are the growing size of ships due to alliances and mergers on one side and on the other side the need to keep container volumes increasing to pay for the requisite infrastructure changes. One thing is obvious in the ocean transportation environment, ship size will continue to drive the size of the cranes necessary to serve them. Figure 1 illustrates the evolution of container ships since their debut in the 60’s.
There is even talk of ships as large as 18,000 TEU sometime in the future. Is there no end to how large a ship could be designed? Aside from physical harbour constraints another impediment that may slow down the size increases of these giants could be propulsion power.
The Emma Maersk requires 109,000 brake horsepower to maintain a transit speed of 25.5 kts. Some experts believe that engine manufacturers will find it difficult to squeeze more power from present propulsion designs. Even so, there is little doubt that vessels beyond the size of the Emma Maersk will eventually materialise.
Improving turnaround time
Ship lines are seemingly in a position to ‘have their cake and eat it too.’ Despite the larger dimensions, almost doubled compared to 40 years ago, they’re demanding fast turnaround times for their vessels since ‘time is money.’ From a terminal operator’s perspective, there are only three ways of improving the turnaround time for a container vessel:
1. Employ more cranes, either on one side of the ship as in most onventional wharves, or work both sides of the ship such as incorporated in the Ceres Paragon ‘Ship in a Slip’ scheme in Amsterdam.
2. Employ tandem or multiple lift cranes such as the one shown in Figure 3.
3. Reduce or maintain the average cycle time of the typical single or twin twenty lift crane in the face of larger ships.
Each of these strategies has it drawbacks. A ‘Ship in a Slip’ approach requires extensive infrastructure capital cost. The tandem lift crane approach requires considerable additional capital cost and potentially higher wharf expense either to build new or modify the existing structure. Based on a capital focused analysis it
would seem preferable for the typical non-hub terminal operator to employ faster single lift cranes, the workhorse of the industry, The key question is: how large and how fast. Let’s look at how size and cost have increased over the years in the race to keep up with the ship size increases.