We have seen it and heard it all before. Economy of scale is necessary to make shipping lines more profitable. Transporting more containers in one-go is cheaper and good for the environment, but is it a really good thing for the port or terminal operator? My last visit to DP World Southampton was back in December 2012 as it marked another milestone when the world’s largest container vessel – the CMA CGM Marco Polo – made its European maiden call to the port. The new vessel, which was only commissioned the month before, has a capacity of 16,020 TEU and is 54m wide and 396m long, making it 51m longer than the Queen Mary 2, a cruise ship that calls regularly at Southampton. The Marco Polo is the largest vessel in the CMA CGM fleet and currently the world’s biggest containership by container capacity and tonnage. It is also the first of six sister vessels coming in service from 2013.
Bigger and better
The Marco Polo might be the largest container vessel at the moment but not for long as plans for a 22,000 TEU vessel are already on the drawing-board. STX of South Korea and Germanischer Lloyd (GL) have already completed a study on such a vessel concluding that such a size could be built without any problems. This would have a major influence on the planning for cranes and [port] infrastructure as such vessels need an outreach of 72m (25-row wide) and a lift height of 52m above rail. Although such cranes can run on the ‘standard’ 100ft gauge, the larger cranes will challenge designers as they have to overcome stiffness, corner loads, weight, and operational issues. Weight will be a major consideration as often the infrastructure will not allow [much] extra weight. Apart from adding extra wheels to distribute the load of the crane, designers will look at reducing the weight of the crane – they can achieve this by for example reducing the weight of the crane trolley, a reduction of weight of 5 tonnes can reduce the overall total crane weight by 50 tonnes. With regards to the operational issues they do not only include higher handling speeds, improved performance and better visibility but in addition the larger crane will also consume more power – 2500 KVA compared to a standard 22-row crane which uses 2200 kVA – so the infrastructure has to be correct.
Market view
For many crane manufacturers it is very simple – the construction of the container cranes continues to follow the trend of the ‘growing’ vessels. In this context, the increase in height and waterside outreach are the dominant criteria. According to Ireland-based Liebherr Container Cranes (LCC) the present continued drive for larger vessels and the demands for increased turnaround times from shippers are driving crane developments. This is leading to an inevitable march towards larger automated/semi-automated cranes in larger ports or green-field sites. With the larger ports achieving increased productivity, smaller ports will have to follow suit to stay competitive say Liebherr. This has led to manufacturers incorporating a number of different technologies, such as semi-automation, remote diagnostics, positioning systems and perhaps even remote control to allow the necessary improvements that increase productivity. Furthermore landside operations will have to adapt to keep up, so optimisation is essential. As a result LCC expects that sharing of information between the STS cranes, the TOS systems and landside equipment and optimisation software is sure to be at the forefront of developments in the coming years.The arrival of larger vessels will of course necessitate larger cranes, but companies such as Liebherr Container Cranes are capable of developing innovative new products such as the double boom STS cranes recently commissioned in Aliaga, Turkey, and they are sure to continue to innovate in developing the container crane industry.
Similar answers come from Uwe Pietryga, Managing Director at Kocks Krane. “The trend – in our opinion – is going towards a specialisation of Ship-to-Shore (STS) cranes which are especially designed and optimised for different tasks,” he said. “On the one hand, cranes should be equipped with many technical extras, such as automatic modes, safety devices, cameras, monitors, remote operation, etc. On the other hand, there are also a number of projects where the only focus is on having a cost-effective crane.” A couple of years ago, Kocks Krane successfully developed their Power Damper to [counter] combat the movement of the crane during operations and high wind. They used simulation to assess the impact on the steel supporting structure under dynamic aspects, which resulted in their conclusions on the vibration behavior, crane life and also on the well-being of the crane operator. Another important point Pietryga touches on is the total cost of ownership (TCO). According to Pietryga both energy efficiency and TCO considerations are becoming increasingly important in product evaluation and for this reason Kocks Krane sees some positive aspects in the market and increasing opportunities for European crane suppliers. “Even basic concept considerations, such as machinery house trolley or semi-rope trolley are no longer just decided by corner loads but seen in the context complete TCO considerations,” Pietryga said. “Basic statements about the disadvantage of a machinery house design are untenable, weight disadvantages of the past are compensated by modern constructions. We would like to express that we see clear advantages for small STS cranes with semi-rope trolley for lengths up to 80m because of the possibility of using a simple system without catenary trolleys.”
Shine a new light
One of the responses we received came from Michael Jordan at California-based Liftech Consultants. Jordan addresses some of the issues of concern to the crane designer and he is only speculating based on h
is experience and concepts Liftech has studied but addresses our question of what to expect over the next ten years. According to Jordan computer controls will dominate. Nearly all motions will be automated. The operator will not be on the crane, but instead in a remote location. The ship trolley will transfer containers to and from the vessel, the traditional way. The on-deck containers pause at a deconing platform on the crane. The motions that cause lateral displacements will be coordinated with the structural response of the crane. This will control sway. The position and speeds of the hoist, trolley, and gantry travel will be continuously monitored and altered to suit the dynamic response of the structure to the particular demands – lifted load, wind, vertical and lateral inertia forces.
Structural problems will be detected and corrected before their consequences are serious. Eventually, fatigue crack initiation in critical members will be monitored by acoustical or ultra-sonic measurements. This will allow the structures to be lighter and more reliable. Additionally, an acceptable risk approach will be accepted by the industry. Jordan believes the cost of failure needs to be balanced against the cost of the wharf and structure. The integration of machinery motions and structural response is long overdue says Jordan. Cranes are still designed to control the structure’s response to nearly arbitrary mechanical forces. In his view this wastes materials and increases the cost of not only the crane structure, but the wharf as well. The cooperation of the structural designer and the drive control designer will reduce cost and increase production says Jordan. Not only should crane designer and the control designer cooperate, but the wharf designer and crane designer should cooperate. A balance between the costs of the crane and the cost of the wharf should be reached. Often a relatively small increase in the wharf cost would allow significant savings in the crane cost. Of course, part of reason for the less than economic solution is: one party often owns the wharf and another owns the cranes. Since an economic solution is best for all the stakeholders, Jordan expects cooperation will eventually evolve. Jordan also continues to look at new crane developments within the market place and possible solutions but perhaps more importantly looks back at some of the concepts that have been proposed but not made the grade or are still looking for investment. We will include his full article on the evolution of ship-to-shore cranes in our Container Crane & Components Supplement published in May.