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PostPosted: Thu Sep 26, 2013 2:53 pm 
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Location: Shelter Island, NY
So, would it be possible to have a two-person catamaran that could go up on hydrofoils in the same way as the AC72s? Or is there just not enough speed? In the wake of the America's Cup, is Hobie working on anything? (I know, "in the wake of" is a bad pun)

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PostPosted: Thu Sep 26, 2013 2:58 pm 
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Location: Oceanside, California
We did it in the 90's! You will note that the foils are VERY similar to ours.

Its called the Hobie Ketterman TriFoiler!

Hobie TriFoiler

Specifications
Length: 22'
Beam: 19'
Mast Length: 18'
Sail Area: 215 Sq. Ft.
Weight: 320 lbs.

TriFoiler Owners Manual, TriFoiler Parts Guide, Support Pages: http://www.hobiecat.com/support/index.html

Promotional Video:

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PostPosted: Thu Sep 26, 2013 3:01 pm 
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Foiling boats are technical, expensive, limited to narrow conditions, difficult to manage... We had a lot of fun with it, but not the best product for general public use.

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PostPosted: Thu Sep 26, 2013 4:34 pm 
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Location: Jersey Shore
Paris wrote:
So, would it be possible to have a two-person catamaran that could go up on hydrofoils in the same way as the AC72s?


Look up the C Class, Little America's Cup.

Yes, foiling catamarans are possible on a smaller scale and have already been done.

Is it practical for the average sailor? No.

Is it cool? Hell yea.

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PostPosted: Thu Sep 26, 2013 5:41 pm 
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A-Class isn't that far from it. Mischa is foiling downwind in the right conditions.


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PostPosted: Thu Sep 26, 2013 5:45 pm 
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Location: High Point, NC
Yes, foiling is "cool" but it's not quite the same thing as sailing. I think that many of the folks that want a foiling cat, if they actually had one, would find that they miss the heeling, spray, rolling, feel of the water, etc. Foiling is flying a foot off the water. Yes, very exciting, but a completely different feel than "sailing." For those that haven't done it - it's not quite what you think it is.

It's exciting to watch, but maybe not quite as exciting when you're the one on the foils.


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PostPosted: Thu Sep 26, 2013 6:50 pm 
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Tom Kirkman wrote:
Yes, very exciting, but a completely different feel than "sailing." For those that haven't done it - it's not quite what you think it is.


And you're making this statement based on first hand experience with foiling sailboats?

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PostPosted: Thu Sep 26, 2013 6:54 pm 
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Yes.


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PostPosted: Fri Sep 27, 2013 5:21 am 
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Location: Sarasota,Key West FL
srm:
Tom has a Trifoiler, and I have a Tandem Island that I put foils on a couple years ago ( I got up on the foils a couple times only before giving up on them), I think we both agree on one point, once you get up on the foils a couple times there is a "been there done that" feeling that comes over you.
At least in my case I spent quite a bit if time designing and building my foils, then at the end I was a little disappointed in how narrow the foiling window was for me. At least around here (south Florida) it's only once in a blue moon that we get the conditions that allow foiling (winds over 15mph without a lot of chop). Perhaps if I had started with a better boat like an F18 or something with massive sails, I would have had better luck. The surprising part for me was how difficult it was to get my boat up to the 8-10 mph threshold with the double drag of both the hull and the foils together (double drag), was something I had not anticipated (especially with the TI). With all 265 sq ft of sail out I was only able to foil down wind (spinnaker was doing most of the work). Foiling upwind was completely impossible for me. once I complete my wing sails I may be able to get the old foils out and give it another try upwind. But to be honest I'm in no hurry since I have the attitude " been there done that", and just want to enjoy what I have for a while.
It's fun for me just designing and building the stuff, then trying it out, but I get bored quickly unfortunately.
Bob


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PostPosted: Fri Sep 27, 2013 11:12 am 
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Paris wrote:
So, would it be possible to have a two-person catamaran that could go up on hydrofoils in the same way as the AC72s? Or is there just not enough speed? In the wake of the America's Cup, is Hobie working on anything? (I know, "in the wake of" is a bad pun)


[youtube]http://www.youtube.com/watch?v=taJYT4eAiWE&feature=youtu.be[/youtube]


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PostPosted: Fri Sep 27, 2013 11:17 am 
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I REALLY enjoyed sailing the TriFoiler when we were selling them. Fast and turned like a slot car! That G-Force would pitch you right off a cat or open kayak (reference crew overboard during the cup too). You had to set your shoulder against the TF cockpit rail or risk getting a bruise when gybing. You sat down inside the cockpit and the rails were shoulder high.

Ultimately... as noted above. Conditions were narrow. Crashes were catastrophic. Putting them back together is expensive.

I love foils, but... they are not great recreational equipment in my opinion.... and the Hobie TriFoiler was the most user friendly version of a foiler ever. Self tending foils... once up, you didn't even have to think about it.

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PostPosted: Fri Sep 27, 2013 11:55 am 
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If I lived on San Francisco Bay, I would probably have a Moth or something that foiled. Living on a N.C. lake, it would be an expensive short ride on rare occasions, so no thanks. Like others have said, been there done that. I can't even think of another place, other than SF Bay, that you could figure on using it most days. SF bay still ranks as my most favorite place ever to race on, but I don't want to live there.

After sailing one of the cats with the curved foils, if someone gave me one of those boats, I'd change the boards-I sure wouldn't buy one of those boats.


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PostPosted: Fri Sep 27, 2013 1:44 pm 
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I'm not saying foiling is better nor worse, just completely different and I think many might find it so different from what they have come to know and love, they might find it's not for them.

I'm not about to sell my TriFoiler. It's great. But I also bought a Weta shortly afterwards because I still like the feeling of traditional sailing.

............


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PostPosted: Sat Sep 28, 2013 8:33 am 
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Paris:
I believe the main development on the AC 72's that makes them really go fast is not as much the foils as the wing sails. I believe the main engine on those boats to be the wing sails (2 part articulating wing main, and wing jib) making the boat go incredibly fast (2x windspeed upwind, and 3x windspeed downwind). Plus a really large bag of money of course.
The foils in my opinion act like a turbo charger giving the boat an additional 10-15% boost above what would be achieved from the already very efficient cat hulls by reducing the wetted area.
My opinion of wing sails is they have an advantage because the heeling moment (the force trying to tip you over) is greatly reduced with wing sails vs conventional sails. All the math and physics are different and I foresee a new era in sailing just around the corner. (just my opinion of course)

Here is a pic of my wing setup on my Tandem Island.
Image

This is a pic of the wing jib by itself. ( the wing main is designed but not built yet), this was a pic I took during testing of the wing jib a while back.
Image

The main will be raised by the halyard and reefable (but not furlable), if conditions get bad I will just lower the main wing while out on the water and sail using the jib alone (which has been tested in 30mph+ winds, and is very safe).
The main will be soft semi-rigid (kind of like a parafoil using the air intakes in the front leading edge to make it hard and rigid). The main frame will be just a square box frame (mostly carbon) which will be stepped before launch. The 2 piece wing for the main when reefed will be piled up at the bottom, then hauled up with the halyard (similar to a standard sail on an H16). Once up and pulled tight air coming in the leading edges puffs the wing foils rigid (like a parafoil). The mainsail automatically follows the wind, and is articulated in the center to get the correct camber (look at AC72 videos to see how the wings work). Control is very simple, you just tug on two lines to bend and articulate the joint between the sails. both the main and jib automatically follow the apparent wind, from whatever direction the apparent wind is coming from. Even with my current setup (with a conventional main (not a wing), and a wing jib). I am sailing downwind faster than the wind so the sails are pointing back as if you were sailing upwind (a very strange sensation and opposite to normal thinking). The apparent wind generated from the forward motion is what propels the boat. This is why my spinnakers no longer work, and I can no longer use them (totally different concepts and thinking).

Once the new main sail is completed I plan to dust off my old foils that I built a couple years ago and put them back on the TI. I will hopefully be able to foil upwind then. My current foil setup only works downwind with my huge spinnaker out in winds over 15 mph and is so limited to exact conditions the foils are not worth the effort.
Of course if I had started with a wildcat or a Falcon F18 it would have been a different story, but I'm on a very limited budget, I would never be able to afford a wildcat. If my new wing main costs me over $500 bucks (my planned budget) it will not be in the cards. The now completed wing jib cost me about $150 bucks in materials, and of course I had to design and build it all myself in my garage.
Don't be fooled by some of the videos showing boats on foils racing downwind with huge spins out, that's pretty easy to do and I can even do that with my very limited TI on my foils.
I think what separates the men from the boys is being able to foil upwind. The Trifoiler is a great example. The trifoiler was designed in the early 90's (pre-dates wing sail technology) and is still an amazing and awe inspiring boat (easily 15 yrs ahead of it's time). I simply can't even fathom how fast it would be if it were upgraded to the latest wingsail technology, you would simply fly in all conditions, upwind, downwind it just wouldn't matter. The current design is fairly limited to very specific conditions, I suspect mostly because of the sail designs, all the rest (ie... the hull design, the foil designs, etc) would likely be the best platform to start with, as in everything is already figured out and proven out, and really works well.
I'm still amazed that there are very few boats out there using all this stuff, I would think that everyone would be all over this stuff.
Just my 2 cents, and of course my own opinions
Bob


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PostPosted: Sat Sep 28, 2013 2:01 pm 
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No doubt a wing will be more efficient than a fabric sail, but the real difference is the foils - reducing the wetted surface of the boat by getting the hull up out of the water.

A cat takes off when you fly a hull because you instantly reduce the wetted surface by 50%. After noting the tremendous acceleration when I foiled the TriFoiler the first few times, I did some math and it turns out that when it rises onto the foils the wetted surface is reduced by something like 98%. No wonder it takes off like a rocket when you get on the foils.

Jimmy Spithill said something about the AC72s early on that resonated with me as soon as I heard it. He was asked about foiling and said that you immediately notice two things - the odd quiet and the tremendous acceleration. The only exception I'd make is that it doesn't get quiet - there is a high pitched whine coming off the foils that is rather loud, but all the other normal sailing sounds of water and wind do indeed disappear. I suspect this is what he meant. It's almost eerie in a way.

I certainly won't take exception to the acceleration - I knew the TF would be fast, but it never occurred to me that the boat would push you back in the seat like it does. Once it comes up on the foils it's like somebody came up behind you with a jet engine and slammed into your backside. It doesn't just accelerate - it leaps out and screams off.

Getting the hull out of the water is the thing. That's where the speed comes from.


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