Sailing World November 2003
YACHT DESIGNER JUAN KOUYOUMDJIAN (koo-yoom-JOHN) is best known for the IMS 50 Krazy K-Yote Two. The French boat showed up at the 1999 Admiral's Cup with a radical unstayed wing mast that made opponents nervous and had measurers simultaneously scratching their heads and flipping through their IMS rulebooks.
The boat was issued an IMS certificate, but the rating was changed at the eleventh hour and owner Ortwin Kandler withdrew from the competition in protest.
That disappointment reinforced to Kouyoumdjian, who was 27 at the time, that significant progress in yacht design would come from outside sailing's restrictive rating rules. To make a living, he still toils in the mainstream he was employed by Prada during the 2003·America's Cup and Le Defi in the two previous campaigns - but he also takes ample time to think outside the box. His latest project is ·a 116-foot monohull with a canting keel and a canting mast. It should do 30. knots, easy. For Kouyoumdjian, that's just a start.
Tell us a little about this new boat?
It's 116 feet and it will be launched the 48th of September the Malaysian Prime Minster. The name of the boat is Maiden Hong Kong and the owner of the boat is. Frank Pong. [Ed's note: At press time, last minute changes.delayed the launch.] What sort of a initial design brief were you given by Mr. Pong?
He said that he wanted to go very fast. His idea was to do something no smaller than 100 feet and not bigger than 130 feet.
It has some radical features, especially for a boat of that size.
We have a combination of things. The rig is a wing mast that rotates and cants. We have a canting keel with a tungsten bulb, which have been used by the French for quite aw hile, but not in this size. [Ed's note: Tungsten is 70 percent denser than lead, but is extremely expensive, difficult to work w.ith, and illegal under many rating and box rules.] It's a bunch of things that have been used and proven to be really fast, but never combined on a monohull.
How do you ensure the package will perform as expected?
First of all, I surrounded myself with people who have done it before. I must underline in particular the help of Laurent Bourgnon. He spent a lot of time on the rig. What scares me about this project is that we might have pushed the limit too far. At the dock, with the mast and the keel and ballast all to one side, the boat heels 35 degrees. I'm kind of scared that when you're going out there and hitting high winds, it's going to be a difficult thing to control.
What sort of considerations did you take in determining the size?
The most time we spent was trying to find what was the biggest size of the boat that would allow us to sail faster. When you get to a certain size, sailing faster doesn't mean more length. We thought that a boat that size would be long enough to do a good average speed, but small enough, if may I say that, to handle sails going up and down without any problems.
This boat uses a canting keel system and has both a forward and, aft foil for steering. How does this system work?
We have an aft rudder that's separate from [not linked to] the forward foil. I'm calling it a foil because it really isn't a rudder. Imagine a foil with a trim tab. In the most recent Cup campaign we tried to link the aft rudder with the bow rudder and it didn't work.
So what is the role of the forward foil?
The forward foil provides part of the side force of the boat. The rate at which you load the forward foil is dependent on the limit [angle of attack at max helm] you don't want to go over on the, aft one. Having said that, you want to load the forward foil as much as you can because, as well as providing the necessary side force, what you're doing is lifting the bow up and I believe it's very important on fast ocean going boats.
The mast is impressive as well. How will it work?
The mast will cant 7 degrees that number is limited by the beam of the boat. The advantage is dual. One, you're using the weight of the mast, which in this case is just over a ton, in your favor. You're using that cant to reduce the heeling of the boat.
The second is an aerodynamic advantage; for every 2 degrees you cant the wing mast, there is almost a quarter of a degree increase in the apparent wind angle. So at 7 degrees, there is a 1.5- to 2-degree increase in apparent-wind angle. It doesn't sound like much, but when you're out there sailing, it makes a huge difference.
How is the mast constructed?
We spent a lot of hours deciding what would be the best balance between stiffness and weight. We compared solid laminates against sandwich laminates. In the end we decided a single skin would be more reasonable even though it was a little heavier.
There are still peculiar things that happen when a mast is a sandwich that myself and none of the engineers working with me could understand. The carbon we used is a little bit out of the ordinary because it's a high-modulus fiber. We're using a fiber called M46J, which is made by Mitsubishi in Japan. It's actually the same fiber I used for Krazy KYote Two in 1999. It's not used much in the world of sailing, mostly because the rules don't allow it.
OK, so let's get down to some numhers. How fast is this boat going to go?
With 20 knots of true wind, the boat will be hitting 30 knots at between 48 and 52 degrees apparent-wind angle. It's interesting that the biggest apparent wind angle this boat will see is 60 degrees. Within the region of 25 to 30 knots windspeed, the boat will never see a bigger apparent wind angle than 55 degrees.
So I guess that means you won't be packing along any spinnakers?
You don't have any downwind sails. The only time a spinnaker would be interesting would be in 35 knots or more, in which case you would be crazy to put it up. Your design is now a few years old have you thought how to improve it? The skipper, Laurent Bourgnon, and Frank Pong have taken the project very intelligently, they're already planning some modifications in the future. Obviously they will go in the direction of lightening the boat and putting in a carbon fiber fin. One of the other possible modifications is morphing foils.
What are morphing foils?
When you get to a certain speed and you're asking a foil to create lift-one side has high pressure and one side has low pressure-the pressures get so low on the windward side the water might boil at 60 degrees. When you get to the certain speed, the water simply boils and the foil cavitates and suddenly luffs the boat up or bears it away. This has been known before with propellers. But we're now in an era where we're seeing sailboats hitting that wall. You can shape a foil to cavitate a little later, but the problem is those shapes are very bad for going at lower speeds. If you start with that shape you don't get to high speed in the first place. Therefore, the idea of having to start with something that can then morph into something else. By using morphing foils you can gain 4, 5, 6 knots extra. It's not something that will help you to keep high averages, but when you're sailing at 25 or 30 knots, if you can have that thing that allows you to go four or fives knots extra on occasion, it's a good idea.
So how do you make the foil change shape? Is it mechanical or material?
It's a little bit of both. Fortunately, nature is on our side here. The overall pressure of the water on the foil is pushing things in the direction you want. There is a combination of an elastic material, like a soft rubber, with a mechanical device that simply, when instructed to do so, stops resisting the pressure and lets itself be deformed by the pressure around it.
This is some pretty radical stuff. How sure are you it will work?
There's a lot of question marks. The fact of cavitation is more than theory, but how to make things like this work is purely theory. I'm sure the first, second, and third attempts will fail and by the fourth we'll get it right. But for sure somebody has to start doing it.
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