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 Post subject: hydrofoil wings for motor boats - usefull for homebuild?
PostPosted: Sat Oct 05, 2013 8:39 am 
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Joined: Sun Dec 15, 2002 1:00 am
Posts: 247
Location: Slovenia
Just a tought....
I saw theese on Ebay. Is there any chance one of those wings could be used for a home made "Hydrofoil for kiting" project?
http://www.ebay.de/sch/i.html?_sacat=0& ... c=50&rt=nc
I have not seen those in real life tough....
Greetings,
Jaros


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 Post subject: Re: hydrofoil wings for motor boats - usefull for homebuild?
PostPosted: Sat Oct 05, 2013 3:22 pm 
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Joined: Thu Jun 05, 2003 3:37 am
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Those things are not going to do anything for a kiter
I think. I have used them on boats. They aren't very big.
They provide a tiny bit of lift at the tail and help with the boat's stability,.
They are more like trim tabs than a wing. And they are usually a bit flexible.


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 Post subject: Re: hydrofoil wings for motor boats - usefull for homebuild?
PostPosted: Sun Oct 06, 2013 9:43 pm 
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Joined: Wed Nov 20, 2002 1:00 am
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Location: rhode island
maybe...

i have a set on my outboard.
they have a nice foiled profile.
approx 1 ft^2 surface area (maybe less)
they are flexible
they seem to work at similar speeds.

they do contribute a noticible amount of lift when getting the boat on plane.
most 18' boats weigh about 2000 lbs , so it would not take alot for a kiter to notice.

could be a cheap / easy starting point while you sorted some numbers.


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 Post subject: Re: hydrofoil wings for motor boats - usefull for homebuild?
PostPosted: Sun Oct 06, 2013 10:29 pm 
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Joined: Thu Jun 05, 2003 3:37 am
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Honestly I think they help with hole shot by reducing ventilation around lower unit, rather than planing area. And they help at speed by acting like trim tabs when you tuck the motor in so you can avoid porpoising on boats that are prone to that -usually narrow, overpowered light skiffs.
These are the 2 problems people usually are trying to solve when they add them to a motor as far as I know...
But they might work for kiting, who knows, they're cheap...
Ones I had weren't really foiled on the bottom though, convex top but concave bottom with ribs, weird, and cheap.


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 Post subject: Re: hydrofoil wings for motor boats - usefull for homebuild?
PostPosted: Tue Oct 08, 2013 2:29 pm 
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Joined: Wed Nov 20, 2002 1:00 am
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Location: rhode island
so , we may be talking apples and oranges here.

but a quick look at the numbers puts you in the ball park

nominal planar area : .74 ft^2 (measured)
consrvative lift coeff: 1.2
denisty sea water : 1.98 slug / ft3
rider weight : 200 lbs

lift=cd*.5*rho* A*v^2
resultant velocity to lift 200lbs = 15ft/sec = 9 kts

?
....i'd like to see how far someone gets with this


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