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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 7:19 am 
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Location: HISC Chichester Harbour UK
I can't see how those foils will contribute much. The trimaran setup is only efficient when the hull and one amas is making contact with the surface. If the foil in the water actually generates any lift, it will lift the amas until the foil the other side is also in the water and will start to create lift also. At this point you will have a lot of drag occurring from both Amas and foils as well as the main hull. Until you overcome this by lifting the whole lot out of the water leaving just the foils and rudder (presumably a T foil?) in the water. Unless you can get a suitable sized air gap under the hull, I can't see you have gained anything. Also once out of the water, how do you trim the ride height?

Looks like a gimmick and a waste of time to me. The AI will eat it for breakfast.

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 7:47 am 
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Location: HISC Chichester Harbour UK
We have several Moth foilers at the sailing club as well as a European and World champion Moth Foiler (Simon Payne). We also have a couple of the RS FF600 foilers that don't work very well. They are compromised by trying to adapt a non foiling conventional boat into a foiler and the balance is all wrong. They spend their whole time with the nose in the air , dragging their ass along. The angle of attack is way too high. We also havel the usual smattering of 14's with T rudders.
Foiling is still a bit of a black art, The Moth being probably the best exponent in the dinghy world at this time, although I am sure there are many people working away at new designs that will eclipse it.

I would be interesting to set the AI up as a foiler, but I don't believe it lends itself to being converted economically. If you are concerned about rudder problems now, you will really have problems with a T foil nailed on it. :)

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 Post subject: Re:
PostPosted: Mon Aug 17, 2009 8:37 am 
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Location: Coram N.Y.
Roadrunner wrote:
Hobie is no stranger to hydrofoils. I believe Greg Ketterman's Longshot (forerunner of the Hobie TriFoiler) set 4 world records, one of which still stands after 16 years (Class A, 1992, 43.55 kts).

Here's a short clip of the TriFoiler in action:
http://www.hobiecat.com/sailing/TriFoil ... 20kbps.wmv

Hobie has a TriFoiler history page here for those who haven't seen it:
http://www.hobiecat.com/sailing/history_trifoiler.html 8)


Figures its out of production! I can only suspect it has to do with safety. Going that fast requires sailing talent and just the right conditions to avoid tragedy.

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 9:29 am 
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Joined: Sat Nov 12, 2005 10:46 pm
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Location: Escondido
From what I understand the production costs make the Trifoiler uneconomical to produce. They weren't your everyday boat, requiring a fair amount of wind to get them up on foils. I think Lake Hodges here was used in some of the testing.

Here's a picture of Longshot resting on its foils:
Image

The only time you can get near this one on the water is when it is waiting for wind:
Image

Here's a Trifoiler getting ready to take off:
Image
8)


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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 9:48 am 
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Location: Coram N.Y.
Thanks Roadrunner-great shots.Never considered production costs . You`d think it would eventually pay for itself though. Im still waiting for a faster propulsion system(I know thats sacriligious-dont wanna be struck by lightening)I love the Mirage drive but am pro prop also.
Almost bought a Wavewalker years back. Dont know if they`re still in business. Their drive goes to 10mph.Or so they say.
Its amazing in this day and age no one has been able to come up with new human powered technology that outdoes the traditional stuff.
Someday... :idea:

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 11:16 am 
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Aledal wrote:
Almost bought a Wavewalker years back. Dont know if they`re still in business. Their drive goes to 10mph.Or so they say.

I demoed one 9 years ago. Here's a promo pic from their website:
Image

The only way I think that boat could hit 10 MPH is going down a waterfall. Olympic cyclist John Howard was "escorting" in his custom pedal boat. As soon as I started a sprint his boat walked away from that WaveWalker and I knew then that wasn't the boat for me! That's when I bought my first Hobie. Even before the advent of Turbofins that little Hobie Mirage felt like it could just fly through the water -- couldn't wipe the grin off my face! All in all I've had or tried about 5 different pedaling prop systems -- the Mirage Drive outperforms them all in my experience.

WaveWlker is still around sporting a second generation hull. Funny, I've only seen one in all those years. I have the feeling it's one of those back yard operations. Nice folks though. 8)


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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 11:36 am 
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Thanks but thats not the "Wavewalker" I was talking about Roadrunner. There are two of them. This Co. was based out of Washington State. I think the owners name is Harry Howard? Talked to this gentleman on the phone some 15 minutes.Great guy.We talked about Hobie!!. I think the video is still on YOU TUBE?
Go to google images
Wavewalker "Hydroped" Harry Howard...

The boats` main drawback? It weighed in at 120lbs. Low RPM/High torque.

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 12:08 pm 
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Location: Escondido
Here's the more recent version (and no doubt somewhat faster than the one I tested) -- it may look more familiar to you:
Image

Harry Howard is/was president of Hydrocycles and John Howard's brother. Here's a picture of John's custom outrigger called "Pedalos" (also from their website). He set a 24 hour speed record with it. As far as I know it never went into production, but it is one fast boat, especially with him in it! :wink:
Image


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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 12:38 pm 
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Roadrunner wrote:
Here's the more recent version (and no doubt somewhat faster than the one I tested) -- it may look more familiar to you:
Image

Harry Howard is/was president of Hydrocycles and John Howard's brother. Here's a picture of John's custom outrigger called "Pedalos" (also from their website). He set a 24 hour speed record with it. As far as I know it never went into production, but it is one fast boat, especially with him in it! :wink:
Image

I stand corrected Roadrunner. Didnt know they had a lardassy model before hand. Neither did you for that matter. And we have to go back to the original statement that their drive is faster than the Mirage. Body hull differant etc. (Im not looking to get struck by lightening dude)

Let me put it another way-what is faster?
A Roadrunner car/cartoon etc?
Or A 1968 GT 500 Shelby Mustang?

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 2:34 pm 
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Kidding guys. Kidding Roadrunner. I have a habit of offending sailors on this site.
Its amazing I havent been blacked out by now.
If I were me(and I thank my personal God Im not me) I would have blacked myself out by now. :D

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 3:44 pm 
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Location: Coram N.Y.
Roadrunner wrote:
Here's the more recent version (and no doubt somewhat faster than the one I tested) -- it may look more familiar to you:
Image

Harry Howard is/was president of Hydrocycles and John Howard's brother. Here's a picture of John's custom outrigger called "Pedalos" (also from their website). He set a 24 hour speed record with it. As far as I know it never went into production, but it is one fast boat, especially with him in it! :wink:
Image

They sold lots of them. :wink:

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Aug 17, 2009 3:52 pm 
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Posts: 2409
Location: Escondido
Sorry I thought it was a compliment.

I did get to sprint briefly against the one WaveWalker I saw. It was the newer model. I was solo in a not-too-fast tandem Outfitter with no ballast or front plug and was pushing water in all directions. We stayed pretty even. It should have been able to dust me but.... It had the hull advantage, but the Hobie had the Drive advantage. It wasn't impressive.

The best prop system I tried was custom designed by Steve Ball who also has raced some hydrofoils among other things. Here I'm pedaling his converted fiberglass Heritage Nomad (16' long x 28" wide -- almost identical dimensions as the Adventure):
Image

His boat happened to be in the Bay to Bay race this year (5 mile) and did very well. It came in third behind the 2 Hobie Adventures also entered. Props faster? Using same ballpark hulls, I'm not convinced.

Adedal, since you're a prop fan, let me make a case of the Mirage Drive being a prop Drive as well. The fins are nothing more than two single bladed, oscillating, contra-rotating propeller blades spinning on their drive shaft. Because they don't need a 360 degree sweep, the blades can be twice as large, providing the acceleration and stump pulling torque of a prop twice their size! Unlike most props, they are variable pitch so they can operate more efficiently across a greater range of boat speed and RPM (relatively speaking). As you know, most HPV props are designed to be most efficient at one RPM, one boat speed and one thrust loading.

So there you have it -- you've been driving a prop job all along, and a pretty fast one at that!

And to answer your final question, it would depend on whether you're racing on a road or a rock pile. :wink:


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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Feb 28, 2011 11:36 am 
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Location: Sarasota,Key West FL
Hi Guys, interesting subject. I actually have built and tested hydrofoils on my Tandem Island with mixed results. The way I made them was to tie the two 4 1/2 ft long foils to the underside of the front AKA crossbar. The foils angle out and downward (about 20 degrees) touching the underside of the AMA directly under the front AKA brace and sticking out past the AMA about a foot. The foils are 3 ft long 3/8 thick and 2 inches wide (airplane wing shaped). There is a float mounted in front of the foil that automatically adjusts attack angle (like the trifoiler). When the boat is level the foils are neutral and drag is minimal, as the boat tips, the lower foil tips up (increasing attack angle) as force increases. The other foil has a negative angle trying to pull down the other side. They are very easy to take on and off, just take a minute or so, when not in use they sit upside down on top of the AMA, I usually just roll them up into the trampoline when putting everything away. In total I have about $20 bucks invested so far. The heeling force on a TI (force required to bury the AMA) is 250 lbs (huge). With all my 265 sq ft of sail up and the foils working very hard I still have to hike out on the tramps in a reach in higher winds. According to my calculations the foils have less drag than a buried AMA. I sail mostly in lighter winds and everything seems to work well, in heavier winds I wouldn't dare open up any of the bigger sails (you don't launch a 135sq ft spinnaker in 20 knot plus winds, DUH). I also have foils mounted on my Mirage drives (see ultimate Tandem Island post), but have not tried all the foils together yet. It's fun to play around with this stuff.
Bob


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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Feb 28, 2011 2:37 pm 
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Location: Kailua 96734
Like to see some video of this Bob.

How do you steer the boat when lifted?

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 Post subject: Re: TRIAK ama hydrofoils
PostPosted: Mon Feb 28, 2011 3:50 pm 
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Location: Sarasota,Key West FL
Jeeze I never thought of that. Just kidding. Without the foils the boat sits halfway submerged in the water, about even with the mold parting line (maybe 8 inches deep). It's a displacement hull so max speed is in direct proportion to hull displacement. If I can raise the boat say 3 to 5 inches higher, so the displacement is much lower, the boat will go faster (the rudder is still in the water). Actually my rudder is too small anyway ( with my added sail area), so I need to extend it anyway. The boat has pretty bad weather helm in heavier winds (because of the strenthened mast), but out performs pretty much anything out there in light winds. My rudder extension will be very simple. Basically two 1/16 polyethelene cutting sheets ironed together around the rudder like a starbucks coffee holder sleeve. held on by a string looped over the rudder. It is still flexible so it doesn't overwhelm the steering string system ( which is not so great). I'm not one of those crazy moth guys wanting to get 5 ft up in the stratosphere, I'm just trying to keep my ama's from submerging. So far it all works great and the boat stays pretty level when underway. I don't have any intentions of getting to 40 mph plus like the trifoiler. Just keep the boat level, and by butt dry.


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