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Ship speed debate Permanent slow-down?


Ship speed has become a key concern of shipping’s customers recently. Container shippers and cargo owners have been intent on shortening supply lines and cutting inventories. But a growing number of senior industry figures believe it’s time for a re-think.


knots is like producing pineapples in Norway,’ he says. ‘You can do it but it’s a rich man’s commodity.’ In a compelling piece of recent economic analysis, Stopford demonstrates the relationship between the cost of ships’ time, and therefore sailing speed, and the cost of bunkers. In his model, based on a 5,000 mile voyage and various other assumptions, the optimum ship speed at a fuel price of $200 a tonne is 22 knots, but at $1,500 a tonne, it is just 11 knots.


C


larkson director Martin Stopford is one of them. ‘Carrying containers at 25


techniques like cost-benefit analysis’. This, he says, would help us to re- examine the value of time and to quantify costs and benefits not picked up by market price.


Martin Stopford –Clarkson’s


Of course, economic models cannot take into account all variables and Stopford concedes that in focusing on the market price of oil, this particular model excludes other factors including the environment, the future price of oil, the true value of having goods arrive earlier, and the future needs of mankind. But he also points out that oil has been plentiful for a century and, in 2009 dollars, cost an average of just $26 a barrel over this period.


‘But that does not mean oil was


only worth $26 a barrel. Is propelling 100,000 tonnes of cargo at 25 knots the best use of the finite reserves of this finite commodity?’ he asks. In conclusion, Stopford suggests that ‘we should dust off old


Stopford’s arguments may be based on a clever model but his suggestion that shipping needs to slow down is already evident across a range of sectors, and not just because of eye-watering fuel prices. Container lines, whose owners generally pay for their own fuel, were first to implement slow- steaming. The roughly cubic relationship between speed and power is the principal reason, but running ships at reduced speeds also helps to absorb surplus capacity. And for those companies with ambitious environmental targets to meet – an issue which is increasingly falling under the scrutiny of shippers – slower speeds mean reduced emissions. Lloyd’s Register’s David Tozer, head of container ship business, believes box ships could well continue to increase in size but are unlikely to resume trading at 24-25 knots, even when the market is better balanced. Sailing at 18-19 knots instead of 24 knots could cut fuel consumption by 40% or more, and new vessels under construction are already being designed for lower speeds. Maersk’s Triple E-class are the best example. Incorporating a wide range of green features, the twin-


engined ships will have a design speed of 19 knots and, the company claims, will have emissions 50% lower than other vessels on the Asia Europe route, and 20% lower than Emma Maersk and her E-class sisters. Tozer thinks service speeds could fall to less than 20 knots across the board but suggests that more speed flexibility will be required in future.


T


ommy Thomassen –Maersk T


ankers


Ships still need an appropriate safety margin – to catch a Suez convoy, for example, or maintain sufficient headway in heavy weather. The requirement, therefore, will be for increasingly flexible engines capable of efficient operation over a range of loads and speeds. The box sector may have been first to embrace a general slow- down but there are similar moves afoot in the bulk markets too. Tommy Thomassen is a senior director at Maersk Tankers. Largely based on sister company Maersk Line’s findings on running container ships with large slow-speed diesels at part load, the tanker company has implemented slow-steaming and super-slow-steaming – engine loads of 40% or less – across a number of tankers in its fleet.


David Tozer –Lloyd’s Register


Its 300,000dwt Nautilus-class vessels, equipped with electronically controlled Wärtsilä 7RTFlex84T engines, can operate at engine loads as low as 9%, he says. Cutting a VLCC speed from 15 to 10 knots can typically halve fuel consumption. However, since the cost of bunkers is usually for charterers’ account, the chief motivation is to reduce ship emissions, Thomassen explains, but the company is in dialogue with a number of its charterers on a joint approach to this whole issue. 


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