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what is it?

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We think it's one of them new fangled cat-o-morans. What do you think?

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Guest multitranslation

It's a C-Class, what else I don't know.

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A C-class flying cat to dethrone Cammas and his gang?

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a new and exciting one design class catamaran, that will appeal to thoroughbred racers, and family racers alike. With the low cost to entry and the easy maintenance, this class is sure to get a good following. To make this class successful, we have collaborated with used the input of major designers and sailors. Have a look at the foils for example, which are a development of the ones used in the america's cup. Competing on a level playing field with the best in the world means you can focus on tactics and strategy, just like the current AC. Don't be fooled by its simple looks, this is a racemachine sure to bring you an ear-to-ear grin.

Feel like an America's Cup sailor and buy one today!!

 

Quotes from famous people:

 

Juan K: this boat will definitely stay in one piece

Frank C: it has green elements, just like mine

VPLP: we used a new construction technique making it stiffer and lighter. just like our latest IMOCA 60's

Peter Burling: it's a good cat

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a new and exciting one design class catamaran, that will appeal to thoroughbred racers, and family racers alike. With the low cost to entry and the easy maintenance, this class is sure to get a good following. To make this class successful, we have collaborated with used the input of major designers and sailors. Have a look at the foils for example, which are a development of the ones used in the america's cup. Competing on a level playing field with the best in the world means you can focus on tactics and strategy, just like the current AC. Don't be fooled by its simple looks, this is a racemachine sure to bring you an ear-to-ear grin.

Feel like an America's Cup sailor and buy one today!!

 

Quotes from famous people:

 

Juan K: this boat will definitely stay in one piece

Frank C: it has green elements, just like mine

VPLP: we used a new construction technique making it stiffer and lighter. just like our latest IMOCA 60's

Peter Burling: it's a good cat

HA

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Well we know its not Portugese, the Dolphin striker is way too long

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Yup it’s our current C-Class development, following on from my thesis a couple of years ago when everyone went batty about the things…

 

It’s not quite as out there as Norman and the Gang are, but I think we have a fresh approach and feel we have some good concepts.

 

With a bit of push on with the aero of the platform, the rudders mounted on moth esq gantry’s to increase foil separation with an aim of reducing induced drag.

 

Lima: fuck knows what I was what I was thinking with the green but not so sure about the orange neva…

JMOD: you’ve cracked me up, let’s make this happen!

 

Check out the link… and let rip!

 

https://www.facebook.com/BRYachtingDevelopments/posts/1023319411041325

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So 12 hrs that could be a record for the whats it quiz? I could say "Well Done" sept your the designer of that hot little thang!

 

Thats not fair its your boat, your new here, learn the the rules, buy an add, till then just Fuck Off.

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Welcome BRYD,

 

A 2011 Thesis from Manchester University "C-Class Catamaran Wing Optimization" written by Nils Haack is available on the web

 

Please could you disclose what was the subject of yours ?

 

Cheers

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BRYD, looks like a great boat. Do you have to shorten the hulls to use the gantry ,or is it legal? I know Rocker used a similar gantry based on a tube extension but I don't remember the rule detail. Best of luck!

 

2crqe5l.jpg

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This is what Steve Killing said about rudder gantry's in his analysis of Rocker:

 

To gain adequate separation between the underwater
foils we added carbon “exhaust pipes” out the transom – a
stretch of the class rules, but technically legal as we read
them. Since the rudders hang off the back end of these
extensions they had to be stiff in bending and torsion.

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Driftw00d: Copy that, My Bad..



Catnewbie: Thanks! My Uni project was based more on the global design of the cat, which is the general theme for the final year projects at Southampton Solent. It was at the time that these things started flying so was keen to get my head around it all, so I developed a rudimentary VPP based on 3d foil theory, and spent a fair amount of time on the structures. But it’s fair to say we have moved on a bit from there, but happy to share if you wanna take a gander.. Pm me



The Design side of the project is actually collaboration between myself and my good friend who is also batty about the C’s and a very talented systems engineer. The plan for us is to also to use an optimisation approach on the wing and other areas but its based more on methods Andrew mason developed for Alinghi, using Neural nets to map the design space and a GA method to home in on the ideal. I think this is generally the method the AC teams use, though granted there may be a bit of a gap on the resources side!



Doug: Thanks! Yes the plan is to definitely to go to full 7.62m on the hull with the gantry’s extending beyond as its where the gains are. I think Steve killing is right it’s a bit shady but legal. From what I see the Interpretations are:



“Length does not include the rudder fittings, but if the rudder fittings have a measurable hydrodynamic or hydrostatic effect on the hull they shall be included in the length”



So we might be a bit iffy on the hydrodynamic effect, however this would also make all boats currently racing in class with transom hung T-foil illegal so I think were ok!



Cheers BRYD


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using Neural nets to map the design space and a GA method to home in on the ideal. I think this is generally the method the AC teams use, though granted there may be a bit of a gap on the resources side!

 

Hmmm, I really need to think hard to get my head around the mapping of Neural Nets and GAs to the problem. Sounds interesting. Any published info? (Not grasping how a neural net can map the space, it seems this is one thing that they are exactly the wrong thing for, but it is probably my lack of understanding of the problem space and/or terminology.)

 

Resources are trivial now. Just throw it into the cloud. AWS is perfect. Compute for less than the cost of the power you would pay to run the computers, if you are not in a hurry. It makes big compute problems like this everyday events.

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Francis cheers, The Cloud could be the way to go for us. A good estimator between variables would be a better fit that "mapping" probably.

Cheers BRYD,

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using Neural nets to map the design space and a GA method to home in on the ideal. I think this is generally the method the AC teams use, though granted there may be a bit of a gap on the resources side!

 

Hmmm, I really need to think hard to get my head around the mapping of Neural Nets and GAs to the problem. Sounds interesting. Any published info? (Not grasping how a neural net can map the space, it seems this is one thing that they are exactly the wrong thing for, but it is probably my lack of understanding of the problem space and/or terminology.)

 

Resources are trivial now. Just throw it into the cloud. AWS is perfect. Compute for less than the cost of the power you would pay to run the computers, if you are not in a hurry. It makes big compute problems like this everyday events.

 

 

 

Here you go, a bit of light reading for you:

 

https://www.researchgate.net/publication/259716640_Stochastic_Optimisation_of_America%27s_Cup_Class_Yachts

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Here you go, a bit of light reading for you:

 

Thanks again. A really nice thesis. Has it gone much further? I guess once the AC went mutli-hull it all became a lot weirder.

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....Doug: Thanks! Yes the plan is to definitely to go to full 7.62m on the hull with the gantry’s extending beyond as its where the gains are. I think Steve killing is right it’s a bit shady but legal. From what I see the Interpretations are:

“Length does not include the rudder fittings, but if the rudder fittings have a measurable hydrodynamic or hydrostatic effect on the hull they shall be included in the length”

So we might be a bit iffy on the hydrodynamic effect, however this would also make all boats currently racing in class with transom hung T-foil illegal so I think were ok!

Cheers TIME

 

 

Interesting. The rules seem outdated and now it is time to either allow or close the loophole. Pre-foiling (or possibly only pre-T-rudder) waterline length was important and the rules were written specifically to disallow a sugarscoop gantry to increase waterline.

 

Now with the hulls flying above the water the gantries serve to increase the distance between the foils while by themselves having no hydrodynamic effect. As you say they are intended to bring about such an effect by moving the rudders aft. This seems to me in fitting with the original intention of the rule. Why have gantries at all other than to change the positioning and therefore hydrodynamic forces of the rudder?

 

I am curious if there is a theoretical limit to how long to make the gantries. If it was possible would 5' gantries be faster than the ones you are now planning? In other words does the increased length between foils become slower. Perhaps by moving the CLR too far aft.

 

If there is little benefit to moving the rudders much further aft than you now have them the rule could be left there as is, I think. If lengthening the gantries results in more and more speed, perhaps they should be limited in length so that the C-Class cats continue to look like boats and not bridges.

 

I guess the fundamental question in the gantries in foiling boats is if they change the effective sailing length of the boat, like a sugarscoop would in a non-flying boat.

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Here you go, a bit of light reading for you:

 

Thanks again. A really nice thesis. Has it gone much further? I guess once the AC went mutli-hull it all became a lot weirder.

 

 

Yes, I used the same techniques to optimize the hullshapes of the Oracle cats for the 2013 America's Cup, see this article for more detail.

 

The optimizer predicted that narrower and rounder hullshapes with deeper transoms would be faster, particularly at high lift fractions upwind, and that the fatter, squarer mid-sections of the ETNZ boats would be draggier in those conditions, a result that I think was shown to be true in practice.

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