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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Wed Jan 27, 2010 5:20 pm 
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Joined: Fri May 01, 2009 11:44 am
Posts: 15
Just came back from picking up the 9.99€ fins I ordered.
And to my surprise They ( decathlon) where on sale and had a bundle of wind surfing accessories ( probably belonging to some boards they didn't have any more ( bic nova(?)) , that included:
1- huge ws fin g10
1- smaller us box fin
4 - straps
bolts and more....
...only for 15€!!!!
### I must be in tune with the universe ###

So I bought two of these ( the only ones)
plastic fin problem resolved!
I'll reshape the huge g10s and make the us's smaller (for the back)
plus 8 new straps!!!
$$$ only one of these g10 fins would probably be 70€ or more!

But now I have to rethink the fin positioning....
I'm also no expert, and have no big expectations
and i have been studying the relations between centre of straps and centre of fins
to understand where to put mine
( still working on the rogue wave, and I already stumbled with norm's (nice one) - Stance on race board - topic )


Attachments:
File comment: relation between centre of straps and centre of fins (updated) , my board is actually the tail part so the outline resembles more the north2009 , it will also miss a bit nose kick but I intent using it only for light wind
g2924b.jpg
g2924b.jpg [ 195.03 KIB | Viewed 1232 times ]
File comment: friends board
IMGP0058.JPG
IMGP0058.JPG [ 103.07 KIB | Viewed 1232 times ]
File comment: bundle unpacked
IMGP0062.JPG
IMGP0062.JPG [ 132.18 KIB | Viewed 1284 times ]


Last edited by ANTONIO GUARDIOLA on Thu Jan 28, 2010 5:58 pm, edited 1 time in total.
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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Thu Jan 28, 2010 5:16 pm 
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Joined: Fri May 01, 2009 11:44 am
Posts: 15
Kite Rider wrote:
ANTONIO GUARDIOLA wrote:
cheap plastic 20 cm fins = 20€


The lateral force on the fins is huge. Last summer, I kept breaking fiberglass fins one after the other that were meant for surf boards and experimentally used on a race board, until they were made in G10. Do not be surprised if you break your fins.

Norm


Norm
when you say they broke, did you mean the probox ones ( like on the stance post) or later fiberglass ones on u.s boxes?

AG


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Thu Jan 28, 2010 5:48 pm 
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Joined: Tue Jul 01, 2003 5:24 am
Posts: 55
Location: Eastern Canada
Yes, I mean the probox fins that were made out of fiberglass. US-type fins are somewhat thicker, and the base of the fins is longer compared to probox fins, hence non-G10 fins may resist better.

Norm


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Fri Jan 29, 2010 1:36 pm 
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Joined: Fri May 01, 2009 11:44 am
Posts: 15
I have created a new thread:
viewtopic.php?f=107&t=2362600
with the following content:

I'd appreciate your comments and feed back
For a race / freeride light wind ( not for real racing)
1 - should the bigger fins ( if any are bigger than the others ) be the front ones or the back ones ( in a quad set up)
2 - Considering you could tune the position ( back and forth ) with a us box.
on witch ( front or back fins ) would be better to have that option?

cheers António


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Sun Jan 31, 2010 4:33 pm 
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Posts: 15
no replies?
but guessing from the number of views, people have been reading this post...
is it the weekend or is everybody looking for the old boards in the garage?
or am I being naive and everybody here belongs to a kite / board company?


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Sun Jan 31, 2010 5:00 pm 
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Joined: Wed Nov 20, 2002 1:00 am
Posts: 880
Location: rhode island
antonio,
i doubt anyone can completely answer your question w/authority.
but i can provide some clues, which i suspect you already know.
so forgive me if i'm just repeating something you already understand.

the bigger fins are intended to allow you to ride your board flat.
riding your board on its rail to provide upwind lift creates lots of drag.
(despite the fact that it's easy. riding the rail is not an efficient way to go fast upwind)

as per recent windsurfing designs.
high aspect ratio fins are better suited to provide upwind lift.
high aspect ratio boards are best ridden flat to keep you on the surface and minimize drag.

when that happen the center of lift of your board and fins are mostly dictated by the location of your fins. you need to balance the location of the center of lift of your fins with the COE of your kite.
lift from fins is aligned with lift from kite. .... at the same time the board is trimmed for max speed

the better these 2 vectors line up the easier it is to go fast and straight with minimal additional input from the rider.... and minimize drag from the board

any help?
-bill


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Sun Jan 31, 2010 5:49 pm 
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Joined: Sat Jan 30, 2010 5:37 pm
Posts: 83
zfennell wrote:
antonio,
i doubt anyone can completely answer your question w/authority.
but i can provide some clues, which i suspect you already know.
so forgive me if i'm just repeating something you already understand.

the bigger fins are intended to allow you to ride your board flat.
riding your board on its rail to provide upwind lift creates lots of drag.
(despite the fact that it's easy. riding the rail is not an efficient way to go fast upwind)

as per recent windsurfing designs.
high aspect ratio fins are better suited to provide upwind lift.
high aspect ratio boards are best ridden flat to keep you on the surface and minimize drag.

when that happen the center of lift of your board and fins are mostly dictated by the location of your fins. you need to balance the location of the center of lift of your fins with the COE of your kite.
lift from fins is aligned with lift from kite. .... at the same time the board is trimmed for max speed

the better these 2 vectors line up the easier it is to go fast and straight with minimal additional input from the rider.... and minimize drag from the board

any help?
-bill


a lot!
(lots to digest now)
thank you very much

António

olinozanussi formerly known as ANTÓNIO GUARDIOLA ( my name there seemed too minimalistic )


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Tue Feb 09, 2010 11:42 am 
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Joined: Sun Jul 24, 2005 6:39 pm
Posts: 2911
Small volume slalom boards would probably provide the best basis. Something about 235cm by 54 cm and 74 litres. Cutting the tail off between the front and rear straps would give a good shape.

Fins and finboxes are going to have a huge effect on performance though, and its not going to be easy to make a cheap solution. Old windsurf fins are cheap, and big enough to reshape into kiterace fins if you have the talent.


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Fri Feb 12, 2010 11:28 pm 
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Joined: Sun Mar 07, 2004 2:18 pm
Posts: 362
hate to tell you but that nova fin you have is not G10.

it is resin infused glass and moulded, not ground like a G10 fin, it will split and splinter if you are not very carefull when trying to re shape it, how do i know? i used to sell them!

also the head on that fin will need a lot of work to fit your board unless you are planning on fitting deep tuttle box fin boxes.


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 Post subject: Re: Can you convert an old windsurfer into kite race board?
PostPosted: Sun Feb 14, 2010 7:55 pm 
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Joined: Sat Jan 30, 2010 5:37 pm
Posts: 83
james wrote:
hate to tell you but that nova fin you have is not G10.

it is resin infused glass and moulded, not ground like a G10 fin, it will split and splinter if you are not very carefull when trying to re shape it, how do i know? i used to sell them!

also the head on that fin will need a lot of work to fit your board unless you are planning on fitting deep tuttle box fin boxes.


ok thanks a lot

even though its not g10 it will be better than plastic. (?)

i didn't have time to work on it yet
but when I do I'll be extra careful

and no, I'll just make a hole and glue the front ones "in situ"


And the back ones I'll try to fit them in the us boxes ( without the plastic deep tuttle part)

Ag


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