A high-speed diesel catamaran, said to be the most powerful of its kind in the world, recently began ferrying passengers between Rochester, New York, and Toronto in Canada.
Developed by Australian boat-builder Austal, the Spirit of Ontario has slashed a five-hour journey in half, and is one of a growing number of similar projects designed to get commuters off the roads and on to the water.
The 284ft ship is equipped with four 20 V Series 8000 engines developed by German engine specialist MTU. These deliver a propulsive power of 44,000HP and give the catamaran a fully-laden top speed of 45 knots (52mph). The craft can carry 774 passengers, 238 cars and 10 trucks.
Daniel Reinhardt, communications manager of MTU, explained that the engine design was based on a novel concept whereby key technologies – common-rail fuel injection, sequential turbocharging and an electronic management system – were fully integrated into the engine rather than being added on later.
The common-rail system, which has become the automotive standard for diesel engines, allows all injection parameters to be determined individually. While the cylinders are fed fuel through a single high-pressure rail, the injection rate and point of injection is controlled by the individual injectors through the engine management system.
Not only does this system enable considerable reduction in both emissions and fuel consumption, but MTU also claimed that the level of structure-borne noise when idling has been decreased in comparison with engines equipped with conventional injection systems.
Reinhardt explained that while the MTU engine was designed with the common rail system in place, other manufacturers typically build the engine before equipping it with the common rail system afterwards. The problem with this, he said, is that it can often result in a less efficient system where the air is not fully taken into the combustion chamber. The more air you push into combustion chamber, said Reinhardt, the better the combustion.
He added that while traditional diesel engines with conventional injection systems are limited by the fact that they can only be set up for one specific power requirement, a common rail system gives greater flexibility and means that an engine can be set up according to different sets of requirements.
While the common-rail technology is at the heart of the catamaran’s high performance, Reinhardt said that without significant use of electronics within the engine itself the common rail system simply would not work. The Series 8000 engines are therefore controlled and monitored by an electronic engine management system.
He explained that this intelligent system does much of the captain’s work, effectively bringing under the control of ‘one lever’ dozens of complicated operations concerning the engine, gearbox, propeller and clutch. ‘The better the integration of all the different components in the propulsion system, the better the captain’s feel for the boat and the greater its efficiency,’ Reinhardt said.
Further efficiency and propulsion gains are made through the use of sequential turbocharging technology. Reinhardt explained that sequential turbocharging enables individual exhaust turbochargers to be switched on and off during operation depending on the engine’s power demand. This contributes towards the engine’s high performance characteristics and helps keep fuel consumption down.
As with the common rail system, the turbocharger has been fully integrated into the engine casing – something that only MTU has done, claimed Reinhardt. He said that this means the outside air can be condensed to 4.5 times its density when it enters the combustion chamber. He added that competitive engines only achieve a density of 1-2.5 times that of the outside air.
Building the turbocharger into the engine also enabled MTU come up with a smaller, more compact design that allows high-power engines to be fitted into a much smaller space. ‘these engines are relatively smaller than engines of comparable output, and the power density is very good,’ he said.
Reinhardt claimed that the new engine attains the best fuel economy in its performance class, with the common-rail injection system and sequential turbocharging especially contributing to this. This results in a fuel consumption below 195g/kWh across a broad power range and less than 190g/kWh at its most economical point, while keeping the Nox emissions below the limits required by the International Maritime Organisation (IMO).
A less immediate benefit of the MTU engine is its low maintenance requirements. The engine block is designed and laid out in such a way that all of the components subject to regular maintenance routines are situated in a particular area of the engine that is easy to access.
While high-speed ferries account for only 10 per cent of the overall US ferry fleet, there’s a general belief in the industry that ships like the Spirit of Ontario and the Lake Express ferry – which recently made its maiden voyage across lake Michigan – may encourage people to use more ferries in metropolitan areas and reduce the amount of traffic on the roads.
But as well as helping to ease commuter woes, the speed and agility of such craft also recommends them to the military. Indeed, with the Spirit of Ontario said to meet all of the US national security demands for a Littoral Combat Ship, the US Marine Corps is particularly interested.