Forums > Windsurfing Foiling

Kitefoil on a windsurf board

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Created by Dar 3 months ago, 19 Feb 2019
Dar
160 posts
19 Feb 2019 6:57PM
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Any reason this would not work? I can install a rail box on my windsurf board like the Naish Hover. Only thing I can think of is the fus might be too short, anyone have any idea?

This is my foil, (I have the 60 wing but can get a 120 and 148 if necessary) ..... invaderfoil.com/

ZeeGerman
104 posts
19 Feb 2019 10:48PM
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We don't do that!

Paducah
341 posts
19 Feb 2019 11:14PM
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How long is the fuse? Which mast (60 or 90)? A short mast is sort of problematic - 60 is really short, imho, because the odds of foiling out are pretty high, especially in chop. A fuse shorter than 85 will likely be a PITA, too.

I presume you are in South Africa? "South African shipping only. International service is not offered."

Dar
160 posts
20 Feb 2019 12:04AM
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Yeah...I am in south africa. I have a 90cm mast but i suspect i will have to make a longer fus as mine is 75cm. What is a decent fus length?

Dar
160 posts
20 Feb 2019 12:07AM
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ZeeGerman said..
We don't do that!

What dont you do ?

segler
86 posts
20 Feb 2019 12:32AM
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If you look at various pictures of windfoils and kitefoils, you will notice that the kitefoil has the front wing very close to the mast, and the windfoil has some fuselage distance between the front wing and mast.

Therefore, if you mount a kitefoil to a windsurf board, you will probably find that the front wing is too far aft of the center point between your front and rear footstraps. You need that front wing further forward on a windsurf board to balance your feet.

Windbot
73 posts
20 Feb 2019 3:03AM
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Rig fully back and foil fully forwards on the mounting rails it's worth a try. I know someone who uses his Naish setup for both, not sure though if it's a windfoil or kitefoil setup.

I was warned against using my Liquid Force foil setup for kiting as their fuselages have been known to bend when windfoiled. Your mileage may vary. Good luck!

Dar
160 posts
20 Feb 2019 7:15PM
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segler said..
If you look at various pictures of windfoils and kitefoils, you will notice that the kitefoil has the front wing very close to the mast, and the windfoil has some fuselage distance between the front wing and mast.

Therefore, if you mount a kitefoil to a windsurf board, you will probably find that the front wing is too far aft of the center point between your front and rear footstraps. You need that front wing further forward on a windsurf board to balance your feet.


Yip.... I can make a fuselage from plywood and carbon/glass. That way I can re-position the wings etc.


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Windbot said..
Rig fully back and foil fully forwards on the mounting rails it's worth a try. I know someone who uses his Naish setup for both, not sure though if it's a windfoil or kitefoil setup.

I was warned against using my Liquid Force foil setup for kiting as their fuselages have been known to bend when windfoiled. Your mileage may vary. Good luck!



In that case I will probably have to use a lot of carbon/glass to really stiffen it up.

Paducah
341 posts
21 Feb 2019 12:51AM
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Dar said..
Yeah...I am in south africa. I have a 90cm mast but i suspect i will have to make a longer fus as mine is 75cm. What is a decent fus length?


75 is the minimum - Starboard GTs use it. When you get around 90 - it improves longitudinal stability. Going further than that increases stability but at the expense of responsiveness. Also, consider as you push past 90, the stab becomes increasingly powerful because of the longer lever arm.

If you fab something up, take a look at doing it out of aluminum bar - there was a post here where a fellow built a longer fuse for his NP (iirc). I think RobRock on youtube home built his foil with an alum fuse, too. If it looks like your foil is using rebadged parts (ie similar to Slingshot) maybe see if you can compare yours to someone else's, it may make sense to use that instead of fabbing something up. A solid carbon fuse that is stiff enough takes a fair amount of carbon.

Biggest thing as mentioned by others is getting the wing in the proper spot under you - either the fuse or mounting will have to be adjusted. Good luck!

Dar
160 posts
21 Feb 2019 2:58PM
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Thanks Paducah.

WhiteofHeart
106 posts
21 Feb 2019 6:31PM
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Paducah said..

Dar said..
Yeah...I am in south africa. I have a 90cm mast but i suspect i will have to make a longer fus as mine is 75cm. What is a decent fus length?



75 is the minimum - Starboard GTs use it. When you get around 90 - it improves longitudinal stability. Going further than that increases stability but at the expense of responsiveness. Also, consider as you push past 90, the stab becomes increasingly powerful because of the longer lever arm.

If you fab something up, take a look at doing it out of aluminum bar - there was a post here where a fellow built a longer fuse for his NP (iirc). I think RobRock on youtube home built his foil with an alum fuse, too. If it looks like your foil is using rebadged parts (ie similar to Slingshot) maybe see if you can compare yours to someone else's, it may make sense to use that instead of fabbing something up. A solid carbon fuse that is stiff enough takes a fair amount of carbon.

Biggest thing as mentioned by others is getting the wing in the proper spot under you - either the fuse or mounting will have to be adjusted. Good luck!


The F-One fuse is shorter than 75, but way more stable than the starboard. (The wing sits in front of the fuse instead of on top/underneath). So looking at the fuselength is not the only way to go, take into account whether the front wing is on top or in front of the fuselage (also goes for naish for example). Furthermore, a "powerful" stab is not a thing, foilpower comes from the front wing, and its position. The backwing does not add lift, only moves the balancepoint back and forth and increases stability. I tested multiple prototype fuselages for F-One, and extending at the back really does not do much but increases stability a little...

That being said, I would go for a 90cm fuse with a single frontwing and stab mounting. I believe having the frontwing's trailing edge at 13cm from the leading edge of the mast is a good starting point, will do some measurements again soon. I'd add some extra holes in the fuse for the mastconnection, so you can move the connection forward and backward to find the right trim.

Ofcourse it is doable to foil with a kitefoil fuse, as long as the box of your board is in the right place. I've done it, not ideal, but definately works.

Paducah
341 posts
22 Feb 2019 1:04AM
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WhiteofHeart said..

Furthermore, a "powerful" stab is not a thing, foilpower comes from the front wing, and its position.




The default setting is which is why the topic of lessening the angle has come up more than once and someone has 3d printed shims.

Stabs also come in different sizes so if power wasn't a thing, begs the question why use a smaller stab.

RAL INN
VIC, 2689 posts
22 Feb 2019 12:48PM
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The rear stabiliser pushes down to allow you to put enough front foot pressure to counteract it that feels comfortable and that your brain can adapt to.
the further apart the two down forces are the more stable but less manoeuvrability. This may be ok when starting but not so much later when the Slapper checking you out cuts across your bow and manoeuvrability becomes suddenly important.

But of course I don't really care about your geriatric foil problems.
my Spitfire Sup/Surf XXLW is proving both stable and manoeuvrable.
and no mongrel little shin cleaver hanging out back.

WhiteofHeart
106 posts
22 Feb 2019 3:26PM
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Paducah said..

WhiteofHeart said..

Furthermore, a "powerful" stab is not a thing, foilpower comes from the front wing, and its position.





The default setting is which is why the topic of lessening the angle has come up more than once and someone has 3d printed shims.

Stabs also come in different sizes so if power wasn't a thing, begs the question why use a smaller stab.


More rake will feel more powerful because the power is further forward, but it does not add power in anyway. It does require a more adapted stance and might therefore feel too powerful for some. Having your weight over the frontfoot remains the biggest problem for people starting out foiling, thats also the main reason why freestylers pick up foiling way faster than slalommers do.

The same goes for picking a bigger stab, which also increases the downward pull of the stab, or increasing the distance from the mast.

However, the feeling is quite minimal compared to moving the frontwing a cm forward or back. You could see the stab as fine trim and the frontwing position as general trim (thats why most foils have that fixed). Ofcourse, the smaller the front wing, the bigger the effect the stab has, for the differences in power between the front and backwing becomes smaller.

segler
86 posts
23 Feb 2019 1:05AM
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The other thing the rear stab does is lift the sail, mast, boom, and extension. It is all a balancing act. You can fine-tune that rig lift by moving the mast base fore and aft.

Think of the front wing as a fulcrum of a giant lever. If the fulcrum is at the mid point between your feet, you can easily balance the rest of your gear and learn how to control the pitch with body and sail.

Paducah
341 posts
23 Feb 2019 3:34AM
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WhiteofHeart said..


Paducah said..



WhiteofHeart said..

Furthermore, a "powerful" stab is not a thing, foilpower comes from the front wing, and its position.







The default setting is which is why the topic of lessening the angle has come up more than once and someone has 3d printed shims.

Stabs also come in different sizes so if power wasn't a thing, begs the question why use a smaller stab.




More rake will feel more powerful because the power is further forward, but it does not add power in anyway. It does require a more adapted stance and might therefore feel too powerful for some. Having your weight over the frontfoot remains the biggest problem for people starting out foiling, thats also the main reason why freestylers pick up foiling way faster than slalommers do.

The same goes for picking a bigger stab, which also increases the downward pull of the stab, or increasing the distance from the mast.

However, the feeling is quite minimal compared to moving the frontwing a cm forward or back. You could see the stab as fine trim and the frontwing position as general trim (thats why most foils have that fixed). Ofcourse, the smaller the front wing, the bigger the effect the stab has, for the differences in power between the front and backwing becomes smaller.



Functionally, to the beginning foiler, the tendency for the foil to lift is what he or she will refer to as power. As you say, a bigger stab induces the foil to exert a stronger upwards force* that either has to balanced by more front foot pressure, moving the mast base forward, moving the feet forward, etc. The same goes for a stab with more "up elevator" - more pitch. The tendency for the board to rise on the foil will be stronger.

As soon as the board reaches foiling speed, there is sufficient lift from the foil. At any speed higher, both the size of the stab and the pitch will create an increasing tendency for the board to rise. A sharper/higher pitch maintains a high AOA on the wing while a larger stab requires more downwards force in front of the foil as it becomes increasingly powerful that faster it goes. That is the power to which I refer. So, yes, the stab, both its size and pitch, contribute to the upwards force (ie power) of the foil that the foiler has to deal with as speed increases.

Rake:marseille.glissattitude.com/blog/reglages-windfoil-le-rake.html
Stab angle:marseille.glissattitude.com/blog/windfoil-calage-des-stabs-en-foil.html




Edit: Deleted some stuff that upon further reflection was probably not entirely accurate



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"Kitefoil on a windsurf board" started by Dar