Feature 3 | FAST PASSENGER AND FREIGHT FERRIES
However, he says LNG is proving to be a
very safe fuel. While some might think that because it is a gas this is not the case “that has now been proved to be wrong. Te LNG industry has an extremely good safety record, largely because the fuel can only burn at a very small window. As a liquid it doesn’t burn at all, but when expanded to a gas it has to have almost exactly the right mixture of gas to oxygen or it doesn’t ignite, so it is proving to be very safe. “It doesn’t easily ignite in the engine, so 1% of distillate is included to fire it. It does have negatives, Clifford says,
because it typically produces a little less power for the same size engine, which means that for fast ferries, slower speeds are required, typically under 30knots, compared to 35knots before that. For the future, speeds can be reduced still
further to 15 to 20knots with smaller engines because the ship at that point, although going no faster than a conventional ferry is only half the weight, so it is burning half the fuel. “Te future is not so much fast, but fuel
economy,” Clifford believes. There have been issues relating to the
placement of LNG tanks and their proximity to passengers. In a catamaran the tanks are located in the hulls which are isolated from the rest of the ship. “Admittedly the passengers are above them but they are two more decks above them”. Incat and DNV have been working together on the issue. Te Viking Line ship being built at the
moment has LNG tanks based on the stern of the ship, nowhere near the passengers. “If necessary we could do that as well, but we don’t believe it is necessary. “We and DNV are satisfied that the tanks within the catamaran hulls are perfectly safe. Even if they get damaged by a collision the fuel will only pour out. One of the other aspects in our favour is that aluminium does not suffer in cold temperatures, steel does”. He does not buy the concept of fire risk for aluminium and says it is a “huge misconception. It is not a fire risk material”. Light weight vessels in the oil industry
are much in demand and pose their own challenges, particularly as the oil industry is getting further offshore. For example in Brazil some of the rigs are 100 miles away from the coast and beyond the range of helicopters. “Te oil and gas industry is a very strong candidate for aluminium ships in the future,” Clifford says.
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Fast ferry initiatives with freight have not
been so successful so far, largely because ships have to be large enough. “We are getting there,” Clifford believes. Incat’s I30m prototype “is a ship that will carry a large quantity of freight on the main deck and cars on the upper deck, with bow and stern loading. Te payload is getting bigger as the ships get bigger. Fast freight is definitely not far away. “ In the past few weeks Incat has contracted
a ship on the straits of Taiwan, which has taken some experimental cargo with a target of 400tonnes a sailing from October carrying containers. “Freight is on its way, but with freight you have to be careful with the economics. Te economics of going faster mean you get another sailing in,” he explains. Te Far East offers opportunities and
they are progressing quickly. “We believe the industry is going to be expanding very quickly on the water, there are a number of places where that is going to be happening, but an obvious place is the Straits of Taiwan because of those who have relatives living in China.” Tere are a lot of new ferries required for
Japan also and Korea has taken a number of second hand Incat catamarans. “Korea will need new boats,” he says. “Te future is definitely in Asia, we are not going to write off Europe, but we are not going to wait around while they make up their mind what they are doing”. Te Caribbean is also a buoyant market
and there are now about six or seven fast ferries there, Clifford says. “Two of ours are operating in Trinidad and Tobago and they will need replacing with gas powered versions. Trinidad fortunately has plenty of gas”. Buquebus’s 50knot newbuild will be gas powered. “Te future’s gas, the future’s freight, the
future’s multi-use vessels and generally bigger and slower vessels focusing on economy. Quite oſten you can carry 50% more freight with only a 10% increase in power and that sort of ratio is working as we get bigger and bigger”. With Incat’s new eco-ship design cargo capacity grows as the ship grows. Hydrofoils and hovercraſt all reached a
plateau aſter which they could not get any bigger, he explains, but with the eco ship, the cargo capacity gets bigger as the ship gets bigger. “Tere is no reason to believe a 150m ship wouldn’t be bigger again, particularly if
Gas power for Buquebus ferry
Incat’s 99metre LNG powered passenger and car vessel for Buquebus is due to be delivered in November this year. While the company says that freight operators may not find the turbine solution used by Buquebus attractive, as they do not need the very high speed the turbines provide. However, the switch to LNG does solve a number of issues not least those relating to the introduction of new emissions legislation, and the advent of emission control areas in the US and North America, the North Sea and the Baltic. According to Incat, for passenger services where high speed is essential, gas turbines are a smaller and lighter engine option. The General Electric LM2500 engine being fitted to the newbuild has been adapted to operate on LNG or distillate fuels. The power plant is fuelled by distillate to start, but after ten minutes when the heat exchangers have produced enough gas from the liquefied gas in the main tanks the engine is changed over to gas fuel. On arrival in port, the engine reverts to distillate fuel burning for the manoeuvring process. The LM2500 is a single rotor gas turbine with an aero- dynamically coupled power turbine.
we go a bit slower. Efficiency is working in our favour”. The only way ships will get more fuel
efficient he says is if they displace less water. The Incat Wing project has been under development for a number of years. The ship which looks like a combination of ship and aeroplane largely liſts out of the water on a column of air while the propulsion and steering of the vessel remain in the water in wave piercing hulls. Liſting the ship and supporting its weight on a column of thin air he believes is the answer to lowering the ship’s total resistance and lower resistance
The Naval Architect September 2012
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