Little America's Cup 2010-C CLass-the real one..

Little America's Cup-design

More about how a wing works with neat links: http://www.sailingworld.com/blogs/racing/americas-cup/out-on-a-wing


Summary of all available video from SA,including interviews:

 

Little America's Cup 2010-Oh Canada!

Congratulations on an impressive defence to Team Canada! I have mixed feelings, though, because I was sure looking for a tough series between Aethon and Canaan. Canaans wing is mighty impressive-the best looking C Class wing I've ever seen and most impressive in light air.
Ashby and Spithill fought hard and had a chance when the wind was up...
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Now, its time for a 25' C Class Monofoiler.......
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Match racing? http://www.boatdesign.net/forums/multihulls/heh-heh-34222-2.html#post393272 post #23

 

Hi there, I have been reading with interest and this will be my first post...

After reading Steve Killing's paper on Alfa and looking at the pics of the current boats I am wandering why the hull shape uses a semi circular design.
My understanding is that as Fn increases past 0.35 the optimum catamaran hull becomes more eliptical as the trade off Friction Drag vs Wave Drag shifts.
Offshore multis seem to validate this observation so what is different for a C class?

 

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Welcome to the thread,Stephane*. I'd like to read the paper you are referring to-it would be potentially enlightening. As best I can tell, the rationale for a semi-circular hull has been to keep wetted surface low. But some of the research in the Moth class has suggested that a square or rectangular section with a narrower beam and higher L/B ratio is better in the real world of low speed Moth sailing(which is almost a thing of the past now) as well as helping with early liftoff.
You may already be familiar with Leo Lazauskas, but if not, he has done a great deal of research in this area-here is his profile: http://www.boatdesign.net/forums/profile/leo-lazauskas.html

* misspelling corrected 8/31/10

 

Thanks for the welcome.

The paper can be found at the following: http://www.stevekilling.com/SteveKilling_CSYS2009.pdf

 

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Thanks but I meant the paper or source for your information on the ellipitical hull shape being favored above .35 Froude number. I wasn't clear-I apologise....

 

I see, this is based on some research I did in University using Michelet.
I'll have to dig it out from my files...

This being said, look at most multis, their B/D is not 1 appart from the C class.
So I was curious why.

 

Wouldn't Beam divided by Depth of a section be 2 if it was semicircular-or have I misunderstood?

Interesting article with hull sections compared(displ. hulls only): http://www.multihulldynamics.com/news_article.asp?articleID=208


F18 Wildcat hull:

 

yes, my mistake...

 

I bought some old copies of of 'Yachting World' magazine whilst in New Zealand 6 months ago and thought an article on the LAC from the October 1968 edition might be of interest. Just hope its legible!

 

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Thanks very much ,RHP-that was a good read!

 

Little America's Cup 2010

SA wrapup-lists all edited videos:
NOTE: some of the "music" is trully obnoxious, at least one link is "malformed", but there is some good stuff....


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A wing you can stand on while its in the water?
http://www.boatdesign.net/forums/sailboats/moth-foils-30-7-knots-35-3-mph-11209-75.html#post398527


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Some newly posted shots of Canaans wing with controls at http://lesburn1.blogspot.com

Les

 

More destruction -just yesterday-Aethon broken,another wing gone

From Magnus Clarke on SA:

Cat-astrophe….
Following the I4C aka LAC in Newport last month everybody was left with one big question, “What would have happened if Steve and Oliver had competed?”
We were certainly curious about this question on our team as was Steve. So it was agreed a few weeks after the event that we would get together for a little sailing session to put these issues to bed. It was agreed that Steve would bring his platform to Toronto and Fred would lend them a wing for the session. Aethon would use our 2007 wing which was on Orion for the last event and we used to win in 2007, and Fred and I would sail Canaan in her Current configuration. So on Sunday evening Steve and Oliver arrived in Toronto with Aethon in tow at about the same time Fredo was taking his son the emergency room with a broken arm from a playground fall. Steve came to characterize this event as “The Closure Tour”.

Monday was spent setting up the boat and fitting the Canuck wing to her. Likewise Fred obviously had family things to attend to. The plan was some Tuesday sailing, Fred was not going to make it for Tuesday, but would be on board for the planned Wednesday and Thursday sailing.

So following lunch yesterday we saddled up to go out for a short afternoon spin in the lake. We had been watching the weather carefully as on Lake Erie it was blowing 20 and on Georgian bay it was 20 it was more than 100 KM in either direction of us and we were in a lot less breeze in between, but caution nevertheless. So we drifted through the harbor in 6 knots of breeze, turned the corner and found 10-12 right away. We sailed up the channel (Yes THAT channel) through some chop and headed out onto the lake.

Both boats tacked off of the beach and headed offshore, looking for some slightly flatter water. As Fred was not there I was driving Canaan and had Lawn Boy on the wing, so we were being extra cautious about everything, certainly not sailing at full bore. The breeze was now 12-14 with the odd puff higher than that. The breeze didn’t concern me all that much, it was the chop. It was running at 2-3’ and was stacked up pretty close fighting a slow current on this part of the lake.

As soon as the tender said it was blowing 15 steady, I said, “OK we’re all heading in”. If more breeze came in we would be running down in big short chop with the wrong guy on the back end of the boat so I was being careful. I figured we’ll manage the risk on the basis of the weak link, and that was me driving, not Steve and Ollie, a fully trained and well paired crew. We bore away, burned off some distance, did a chicken gybe and started the long run for home on a broad reach. Looking back upwind we saw Aethon stopped and doing some work. A few minutes later Rob spotted them about a half a mile or more behind us at pace. The tender was with them at the back of the pack herding us all to shore.
We were soon approaching the beach and had to do two more gybes to make the channel safely. Needless to say I had visions of our last crash there, in these conditions, firmly planted in my head so we talked it up on every wave. I commented on my empathy for Fred in these boats as when you are driving, you actually only have a very limited input as to the outcome of any wave. The guy on the sheet has all the control, it was utterly nerve racking driving the boat.

We were just about into the channel with one more gybe to pull off, we watched a huge Police RIB tear out of the harbor, as they so frequently do and they were heading straight to about where we last saw Steve. At this point we were speculating that Steve had tipped it in. A flat spot opened up in a puff, so we snapped in one last gybe and tore off into the safety of some flat water. We backed right off and started looking upwind, knowing it was probably futile. We took our time in the harbor hoping to see them come around the corner. The breeze started to pick up so I made the decision just to get the boat in, what ever had happened to them was done and our job was to get this rig on the beach. We punched the throttle and were doing 17 knots upwind in the harbor.

We got the boat out and the wing in the shed, (Thanks Rossi), I had to run for my kids as my wife was out on the RIB. As I hopped on the launch in the other direction I watched the Police RIB motor past to the club with one Aethon Hull onboard and the other towed behind, it’s beams dragging in the smooth water of the harbor.

Fred and I always characterize a main beam strap failure as our worst case scenario. If it goes, both beams will go instantly, and the wing will crater into the water as the wreckage of the boat runs over it. You will essentially blow the whole show. So seeing the hulls not flying in formation was a very bad sign. Lawnboy and I talked on the phone and confirmed the wing was indeed a write off.

Aethon had headed in after correcting a rudder issue and had been running down wind on a broad reach like us navigating the steep chop. Steve and Ollie were both on the trampoline when a beam broke, followed instantly by the other and the whole show crumpled folding them into the trampoline like a taco. They don’t know which beam broke first.

Big Show, Hogan and Nautichic made a valiant effort to save boat, people and wing. They called up reinforcements quickly but it was all for not. The police got there and gathered up the platform and Steve and Ollie. When they finally got the wing onto the rib it was already in rough shape. Half way in it flipped over right on top of them in a gust, all of them poking through the Clysar film between the ribs. In the short chop the ends of the wing were dragging in the water making steering almost impossible. Eventually they had to unload the whole thing on a beach in crashing surf, or risk a crash into a sea wall in crashing surf, which was the smart thing to do. Sadly however, following all the abuse, the wing was totally dead, a broken spar is the end for these wings.

A few phone calls later and Fred had the full update on the program. As always he was gracious and level headed about things. True to Fred’s nature he also wanted to know how we had been going upwind against the Yanks. They were going great, very well, they pulled out about 50 yards on us over a few miles. to be fair, I think with Fred and I sailing in our normal spots, the outcome would have been different, us faster then them, I cannot say, but not giving up what we were.

So for the balance of Tuesday evening there was discussion, there was analysis, there were more than a few moments of silence for our fallen friends, there were pints and Orange whips.

The “Closure Tour”, well, not quite yet….
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From Big Show on SA:

The aft beam broke first. Steve and Oliver were gone in an instant and when the forward beam snapped it almost looked like it released the wing or flicked it a bit. It was a ghastly look. You can't blame the wing for wanting to get away from that noisy and aweful splash of a wreck.

Darn shrouds.

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And a bit more from Magnus:

Well I have been downloading and analyzing the data from yesterday.

When Steve crashed he had hit his top speed for the day of 20 knots, he was just 900 meters behind us when it happened. We didn't see it because we were bearing away following a gybe and kind of busy.

On the first upwind run, Canaan was slightly faster, perhaps 1% and they were about even on VMG at first glance.

I have not looked at the second segment.

On the third segment we start out very even for 1.5 km, then SHC pulls out somewhat, ending the whole 2.5 segment 100M further down the track, so call it 4% faster and a bit higher too, better VMG overall in the last segment.

Then we head downhill and we were cruising, he was pushing, so there's realy nothing to compare there. He was doing 13-20 downwind for the most part.

The breeze was 12-16 knots perhaps. So arguably right in the cross over range you would expect to see for the boats, accepting that Canaan is probably faster in lighter air, and vice versa.

This however, does not count as closure.

MC

 

Aethon and Fredo's wing: crash and burn

Steve Clarks comments from SA:

I have also been thinking about all this.
The only thing I know for certain is that it wasn't Farr Yacht Designs fault.

The most troubling thing is that the beam design is based on real load data we acquired in 1995 by instrumenting Cogito with strain gauges and sailing on one of the gnarliest days ever. We have had a high degree of confidence in what the loads are, and have been aggressive in our weight reduction program as a result. IFthis beam broke because it was under specified, then we have to revisit the whole load analysis and that will ripple through every piece of the platform and wing. Tuesday was rough, but every major high performance class would have been racing on the lake in those conditions. I expected Aethon to not only survive that sea state, but to excel in it.

This is a much bigger deal than Newport.
In Newport, we crashed the boat.
In Toronto, the boat crashed us.

However this morning Kim reiterated her belief that something must have happened during the capsize in Newport that damaged the beam in some unknown way. How she gets so smart still baffles me, because she closes her eyes and looks away when that part of the video is playing, but I think she is probably right.
Look at 4:06-08 of the CNN video http://www.cnn.com/v...t.club.bk.c.cnn
You see that after the wing is unplugged from the mast step by my falling body it is floating on the water. The platform then crashes down and the main beam hits the wing base. This looks like it is almost exactly where the beam broke the next time it went sailing. It seems that when the daggerboard hits the wing that breaks most of the violence of the impact, but not all. Certainly you would not want to use a thin walled carbon structure as a lever, so my current speculation is that we damaged the compression side (Top) of the main beam in Newport and did not/could not know it. In retrospect, we would have been wise to load the platform up to it's designed stress before going sailing again. It's a mistake I won't make again.

Thanks for Fred, Rob, Magnus, Peter, Ian, Billy & Jen and all of our hosts for everything. You all have better things to do than watch me break boats. I wish we had more to show for it than me walking away shaking my head in bewilderment. Clark in Confusion is a good show for a while, but it doesn't get renewed for a second season.
SHC
Beatings will continue until morale improves.
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More from Steve on SA 9/25/10:



Well the Carbon Coroners have completed the autopsy and concluded that the beam was most likely damaged during our capsize in Newport.
We may undertake some tests to validate this conclusion, but it is well understood that the high modulus fibers are less damage tolerant than their lesser brethren. Most likely the cracking was inside the laminate and so it was not evident to a visual inspection. I should have taken the beam and redone the proof test. It would have taken several hours, but in the end would have saved lots of time and money.
The lesson is worth repeating, particularly as carbon fiber structures become more prevalent in our sport. Don't assume that it's OK just because you don't see anything. If it is a critical component and you have some idea of the loads it has to carry, DO THE TEST. I knew that. Now I feel like even more of an idiot.SHC

Beatings will continue until morale improves.
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editorial comment:
The man is a long way from being an idiot. His sharing of these conclusions -and all the other information he has shared will help lots of people to understand the level of technology involved-as well as what to do and what not to do. Many of us owe Steve Clark a debt of gratitude for his
spirit, guts, determination and willingness to open the book for the rest of us. Thanks, Steve.


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