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Is this the world’s best ship design? The Austal 102 trimaran

By

August 6, 2009

Capable of speeds of 39 nautical miles per hour, the Austal 102 will provide smooth sailin...

Capable of speeds of 39 nautical miles per hour, the Austal 102 will provide smooth sailing in even the heaviest seas

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Shipbuilder Austal first came to Gizmag’s attention in 2005 with the launch of the world’s largest aluminum vessel, the 127 meter Benchijigua Express. The company then started building Littoral Combat Ships (LCS) for the US Navy, based on the same trimaran design. And, now, Austal is launching an even more refined version that improves sea-keeping, passenger comfort and fuel efficiency. This week, Tony Armstrong, Austal’s head of R&D, spoke exclusively to Gizmag about potentially building 20% of the US Navy fleet, how they reduced fuel consumption by a quarter, what sick bags can tell you, and much more.

The Benchijigua Express was the world’s first high-speed trimaran, capable of moving 1350 passengers, 340 cars and over 400 freight lane meters at a rate of 40 knots. Constructed for Spanish ferry operator, Fred. Olsen, S.A., the Benchijigua operates long, arduous routes around the Canary Islands.

Austal are now approaching completion of their next generation trimaran, the Auto Express 102. Now in week 18 of construction, the 102 meter boat is due to launch in October. The bald facts are interesting – it will carry 1165 passengers, 245 cars and 190 lane meters for trucks, travel at 39 knots, and has a 630 nautical mile range – but the story behind the ship is fascinating. Our first question was, why trimarans?

Monohull v catamaran v trimaran. A primer

To achieve real speed and comfort in a ship, the aim is, as Tony Armstrong puts it, “long and thin. But the problem with long and thin is they tend to fall over. They lack what naval architects call stability, which is the ability to come upright. Catamarans get around that beautifully, of course, by putting two long thin hulls side-by-side. And even though there are two, they still have less drag than the equivalent monohull.”

The inherent stability of a catamaran is, however, also its biggest drawback – it rolls very quickly and uncomfortably. “If you’re not careful with the design of the catamaran, the roll period becomes very similar to the pitch period and then the boat tends to operate like a corkscrew as it goes along, which is most uncomfortable.”

“The trimaran is a slightly different approach in that it’s long and thin but to stop it from falling over we’ve put two training wheels on the side like a kid’s bicycle. You’re very slippy in the water with low drag, but you don’t have the high roll accelerations that a catamaran would have. It combines the wave cutting ability of a mono-hull with the stability of a multi-hull.”

The unexpected pleasures of the trimaran

In developing the trimaran, Austal discovered a number of unexpected pluses along the way. “It’s got greater speed for the same cargo weight and the same power compared to a monohull and a catamaran. It’s got better passenger comfort, by which I mean less sea-sickness. It’s got a better sea-keeping ability – able to operate in higher sea states without something breaking.”

Austal also found the trimaran could operate at high speed in much higher wave heights. ”When you go out in waves as opposed to a flat, calm water it’s better than a catamaran, “ says Tony. “And, of course, that’s a practical application because, in reality, most boats are operating in waves.”

There also proved to be less slamming – water hitting the hull – which causes huge loads on a catamaran’s structure and leads to a very noticeable ‘bang’ and the whole structure vibrating. “It’s just not an issue on a trimaran because we don’t have that cross-structure.”

Curiously, the trimaran turned out to produce very little wash. “The waves that it makes – which, of course, impacts on the environment when they come into shore – were fractions of those made by a catamaran. Maybe one-third, one-quarter, something like that. So it’s got that big environmental advantage.”

Tony can think of only one disadvantage to the trimaran: “It’s a little more complex shape to build which, of course, reflects in an increased cost. We’re talking five percent more to build it.”

Learning from the Benchijigua Express

When Austal delivered the world’s fastest and largest aluminum boat to the Canary Islands in 2005, the work didn’t stop there. Benchijigua operated for over a year with a lot of instrumentation on board, gathering data. And, fortunately, the same operator runs two catamarans in the same area, so Austal could make direct comparisons.

“Now, you’ve got to appreciate that Austal sell both, but we found that power consumption is reduced about 20% when operating in a seaway compared to a catamaran in that area. And reduced by as much as 50% when compared with a monohull operating in waves. Which is substantial, because all those power reductions equate directly to fuel consumption reductions.

“We found the vertical accelerations, which are related to motion sickness, reduced about 30% over a monohull. And this one is a sort of non-scientific comparison but one that I’m sure the general public can identify with – the general store of the ship operator issues only one tenth of the sick-bags to the trimaran that it does to the catamaran.”

A perfect platform for going to war

According to Tony, the attack on the USS Cole in the Yemeni port of Aden in 2000 led the US Navy to seriously rethink their priorities. Eschewing traditional warships, which are sitting ducks in foreign ports, they decided to pursue the idea of Littoral Combat Ships (LCS) – fast, maneuvrable and relatively small craft that can operate close to shore. Austal’s trimaran platform was an obvious choice.

“It’s about a three meter draft and you’re talking ten meters plus for a military warship usually, so it’s a huge advantage there,” Tony explains, but that’s just the start. “On the LCS, although it’s only 120 meter in length, quite small compared to other vessels in the US Navy, it nevertheless has the largest helicopter deck of any US warship. It also has the highest helicopter deck above the waterline of any US warship and that’s important because you don’t want to ingest spray in to the helicopter engines.”

In the long term, the US Navy wants 55 of these vessels. On top of that, Austal has an order for two JHSV catamaran troop carriers. “If they build all of the boats that they’re promising to build, by 2014 we will have built 20% of the US Navy’s fleet,” says Tony, “Which is quite astonishing for a West Australian company.”

Coming soon - the new, improved Auto Express 102

A number of refinements will make the 102 an even better ride. Chief among these is the radical use of T-foil stabilizers – horizontal wings on struts that help control pitching – on each “corner “ of the boat. “In effect, we’ve got three underwater wings at the apexes of the boat to give us the greatest control over the ship’s motion. We have sensors on board that sense that one corner’s coming up, so it sends a signal to the wing to provide a force down. All the numbers suggest that that will give a much superior ride compared to even Benchijigua Express, which was good enough.”

Tony and his team also rethought their approach to power. “We’ve got three engines, whereas Benchijigua Express had four, and we’ve done that for reasons of fuel economy. Benchijigua could carry 750 tons with 36mW. The 102 meter can carry a weight of 700 tons and has only three-quarters of the power of Benchijigua, 27mW. So its fuel consumption is less, even though it’s only carrying 50 tons less and it performs in the same area of speed, about 39 knots.”

We’ll soon be able to see the results ourselves, with the 102 due to launch in October. According to marketing, the vessel is already attracting international attention, particularly in China and Taiwan where the trimaran would be well-suited to the challenging sea conditions of the Taiwan Strait.

In the meantime, Tony Armstrong is philosophical about Austal’s relative invisibility. “I get a little frustrated that we do some pretty amazing engineering things here and most of the world doesn’t know about it. But we go on and design the next one and don’t worry about it.”

9 Comments

Regarding whether the new Austal 102 trimaran and Is this the world's best ship design?, probably not. It is already becoming apparent with all of these Austal designs that they rely on fuel inefficient propulsion. Even with the new and improved Austal 102, in a few short years ahead, as the liquid fuel markets go through the roof, it will become apparent that any discretionary service and design such as this that is still so fuel inefficient will become obsolete in the economic environment that lies ahead. As a result it will become apparent that this is actually one of the world's worst ship designs.

Brad Parsons
8th August, 2009 @ 11:50 pm PDT

Brad Parsons seems to be excessively critical about this design. I wonder if he is a boat designer? Anyway, power plants can easily be replaced with more efficient designs as they become available. The main design breakthrough is with the hulls. Perhaps Brad has something better to offer? I somehow doubt it.

windykites1
9th August, 2009 @ 09:33 am PDT

Brad - So what would you propose as an alternative means of powering such a craft?

Rob Irizarry
12th August, 2009 @ 02:38 am PDT

Not quite sure where Brad gets his facts, but the engines used in the Austal 102 are MTU 20V 8000 diesels - by far the most economical form of powerplant to use in fast ocean-going vessels (much more efficient than turbines, and better suited to the high-speed application than diesel-electric). The specific fuel consumption of these motors is some 40% better than ANY equivalent car or truck diesel - at around 190g/KWh at high-speed cruise.

And of course being diesel Brads assertion about liquid fuel is, frankly, total drivel: With minor modifications the motors can even run on gas or agri-fuels.

I happen to work for a company that offers fuel control services for these engines, and they impress the heck out of us with their reliability and performance.

As an aside, IIRC the Littoral Combat Ship actually uses gas turbines alongside the diesels, and must be USN specification, so it is perhaps more pertinent for him to ask his own military why they choose to use less efficient engines...!

snave
13th August, 2009 @ 03:09 pm PDT

I am a student of ccna training program. You are right and on your side on this but what do you think we should do for this?

Matt34
16th August, 2009 @ 11:45 pm PDT

BTW, gas and agri-fuels will not be an answer, snave-ly.

Brad Parsons
29th August, 2009 @ 02:51 pm PDT

Brad, I really dont know where you are going with this... you've eliminated gas (I'm presuming you mean gasoline, or petrol if you prefer), and blanketed all agri-fuels as being bad, so what does that leave? In the category of liquid fuels, this leaves only Diesel, which is already being used... very efficiently.

Ok, maybe you mean gaseous fuels, like natural gas. Oh wait, these are much less energy dense than liquid fuels, meaning that you have to either carry more to go the same distance (which increases load and decreases carrying capacity) or decrease range. Both of these options are counterproductive to making money, which is what ferries are all about. (as an aside, the only places that see a widespread use of natural gases are those that have such an abundance of it [like norway], that it is significantly cheaper to pump it out of the ground than shipping in oil, so much so that it offsets the inefficiency).

might you mean Hydrogen, the so-called "green" fuel? Hydrogen is the smallest element know to man, it is so tiny that it can literally pass right through metal, glass, carbon, basically all known materials. refrigeration is out because it uses more energy keeping it cool than the hydrogen can provide, even when used in a fuel cell (which is about 87% efficient, as opposed to combustion, which is about 40%) So there is no efficient way of storing it. And I'm not going to even get into the problems with making, shipping, and fueling when using hydrogen.

Maybe solar? Can't be that, as solar cant provide a tenth of the power required for a vessel of this size. How about nuclear? Prohibitively expensive to build and maintain, and the eco-hippies will jump all over you like fleas.

So that leaves Diesel, the most energy efficient of all the liquid and gaseous fuels.

Which is why almost all commercial shipping uses it.

Alex Kintz
8th February, 2010 @ 07:55 am PST

also, just an awesome design. the trimaran design is the best of all worlds, and has remarkable seakeeping and efficiency characteristics.

Alex Kintz
8th February, 2010 @ 07:58 am PST

Austal's trimaran is quite an achievement for a hull form that started life as "the world's fastest cruise ship" back in 2001.

After the 14m test model, the original design was 160m long, with more than 300 luxury cabins, most with private balconies.

Ah well... it seemed like a good idea at the time.

Ian Biner
1st July, 2010 @ 10:44 pm PDT
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