Kite Foil Race boards:

JL · Post by JL » Tue Sep 24, 2013 12:11 pm

I don't want to see these links/comments buried in the message board archives: Kayakdoc: Correction: 2000.00 euros for the Sword foil and 3000.00 euros for the Sword foil and board.
Kayakdoc: Hey Luke, One of the foil boards Johnny is using is the MHL Lift Foil Board which costs $1,750.00 (US) at East of Maui. Still a lot of money. The Sword Foil Board is $3000.00...Ouch. I agree that gear costs should come down. My solution is to build the damn things myself. I have some of the NACA foil designs in hand. I am thinking NACA 0018 for the mast, NACA 5313 for the front wing and a modified NACA 63-412 for the trailing wing. Any constructive construction/design thoughts anyone?
Skywalker: that foil is a $4,000 fin. Costs have to start coming down, and production sped up. These boards are getting more and more difficult to ride...looking forward to new tech, but it needs to be accessible.
Kayakdoc: Hey Pasta, I think the foil board designers are finally moving beyond the major limitations of the previous models (they were “easy” to ride, but had limited top end speed) and are now designing for the present skill level of the top riders/racers. The San Francisco racers acknowledged that they could not compete downwind with the AC 72’s (the Americas Cup boats)....(although, even Jimmy Spithill (Oracle skipper) stated the kites were competitive with the AC 45’s). I suspect the SF crew may be trying to challenge the AC 72’s and with new foil board designs they may just get there. If this is the case then the present configuration of race boards could be dead. (See Alex Aguera’s comment on the Heineken Foil Youtube video (just scroll down). Side note: The IKA limited fin design this month, therefore banning the use of wings(foils) for course racing. Might be divorce time for IKA and Course Racing marriage. - Tuesday September 24, 10:00AM
Thankgodiatepastafobreaky: What's up in the Kite Raceworld KDoc? Are foils going to be on top? Adam W. from LV is on one now as well. -
Kayakdoc: Foil roll tacks.....sigh.... http://www.youtube.com/watch?v=GXV3Wdu_Ms4 . Those transitions are awesome !!!

thankgodiatepastafobreaky · Tue Sep 24, 2013 11:22 pm

What's the min windspeed to keep the board up on the foil? If it is always on the foil then the board shape can be just about anything as long as it floats and holds the foil. And then you are dealing with rocket science when it comes to foil design.

And what would the Olympic rules be? Same as IKA or just whatever is fastest in course racing?

thankgodiatepastafobreaky · Tue Sep 24, 2013 11:46 pm

You could build the foils out of sandwich epoxy laminations of wood and carbon fiber and wrap it in carbon. start with rough shapes made of cedar/carbon/spruce/carbon/cedar/carbon/spruce/carbon/cedar

then shape the foils and then laminate the outside with carbon

not sure if this would be strong enough for the mast. maybe all spruce wood in the laminations.

juandesooka · Post by **juandesooka** » Wed Sep 25, 2013 8:08 am

I believe Grant M put together a home-made foil set up years ago, with the mast and foil made of aluminum. Probably heavy but apparently it worked. (I imagine the wipeouts were scary)

The board is pretty much just a platform to stand on, could use an ironing board!

JL · Post by JL » Wed Sep 25, 2013 8:11 am

He found the torque on his lower leg/ankles so strong that he used snow board boots.

He rips on it of course & was on it @ Nitinat this Summer (so I hear)

SmallWaveSteve · Post by **SmallWaveSteve** » Wed Sep 25, 2013 10:37 am

I got to watch him on it for a bit at nitinat, pretty cool to watch, but looked pretty sketchy whenever he got close to the shallows (and the ocean around here with driftwood & kelp would be less than ideal methinks)

KayakDoc · Post by **KayakDoc** » Wed Sep 25, 2013 10:50 am

Pasta, the foils begin to work in very light wind: 3-6 knots. http://www.youtube.com/watch?v=fb68bZjXUbE A larger board makes learning and riding a lot easier when getting up and coming off the plane. Learning with the Carafino board has the board overcome by the foil when trying to launch which leads to a lot of pearling and crashing. Bolting a foil onto an old directional would be a better choice...I think.

My mode of foil design is to not reinvent. The best foil shapes/designs are available on line. I build shaft/tube/mast items like these by starting with 1/2 of the end profile, cut two female copies out of thin plywood and then use these end profiles as guides to hot wire this shape out of EPS foam. These two cut EPS pieces are my mold. After waxing the mold I then take a bicycle tube (this is my bladder) and wrap the wetted out layup schedule starting from the inside out over the tube, usually carbon/Corecell/carbon and then I place this inside one half of the mold. I then clamp the other half of the mold overtop and (lightly) inflate the bicycle tube. This compresses the material against the inside of the mould surface. Let dry and then pull the mould apart and you have the shape you want with very little finishing. For a foil I will make four different molds/parts (mast/fuselage/front wing/rear wing), then bolt everything together (I glue wood or pot urethane into the bolting areas for screw grip). I have used this technique to make very light bicycle handle bars, triathlon bars, paddle shafts, etc..with very good success.

I have included pictures of some of the foil shapes I am considering.

KayakDoc · Post by **KayakDoc** » Wed Sep 25, 2013 11:46 pm

It seems to me that the America’s Cup should just be getting underway. Watching Oracle slow just prior to turning around the upwind mark today, and then blasting downwind, while fighting to keep the windward hull under control, suggests to me that we are just beginning to see the potential of these boats. Give the boys a few more weeks and they would be nailing super high speed turns on a single foil rudder.

The future of kiting is distance x speed. The kites got a serious bump in 5 months of Olympic development. Give the kite designers the right incentive and we will see some more magic. The issues going downwind are not kite design. Anyone that has spent any time on a race board knows that upwind is a trimming, viewing, jaunt....and then as soon as you make the downwind turn it is full trim release and then hold on god damn it!!! The boards/fins are the issue. Once we find a way to let the kite pull without a spaghetti like figure holding on for dear life and allowing the kites to release downwind we are rocketing into new territory. Foils might be the answer, although I wonder if there might be a new foil trimming technology just around the corner. There is a suggestion that a Boeing dynamic rudder foil adjustment system was what put Oracle over the top.

Using a piezoelectric foil adjustment design might allow for unrestricted downwind speed. I can only imagine what it might be like to kite downwind at 60-70 knots. Really scary stuff, but I imagine after a certain speed a whole series of different emotions might kick in. I feel I should go and thread some copper wire into some carbon fiber right now, but I think I might just go to bed and dream about what is coming. Damn it is good to be a kiter right now.

thankgodiatepastafobreaky · Thu Sep 26, 2013 1:12 pm

Still trying to process your impressive method of fabrication. I'm experienced with wood and struggling with epoxy. Would you like an observer / assistant when it comes time to put your foil molds in action?

When it comes to foils on the boards for racing I don't think they need to be so high. You don't see the Oracle boat way out of the water, rising up and down like an elevator. Can't the foil be lower and the bottom of the board shaped to keep it skipping across the water and a V that is integrated into the bottom of the board and foil mast to held cut the chop.

..and last night I was up till 2 getting the final hot coat done on my cedar board #2. It turned out the same weight at the Slingshot I have loved to death this season!

But it has much more concave.

The third is underway and I have chopped the nose off, and widened the board slighlty. The decks are even thinner as I'm going to try carbon under them, and 3 oz epoxy on top.

KayakDoc · Post by **KayakDoc** » Thu Sep 26, 2013 1:26 pm

Hey Pasta, I am sure we can work something out about watching the molding process. I may take a few pictures and post, that may help. I agree about the height of the foils. I think we can get away with a shorter mast...maybe even two foils forward and a shorter one aft. Great news about the weight of your second board. I to have shortened my next Phillet. I laid up the deck this morning (carbon and S glass over 1# EPS). Looking forward to seeing your new boards.

skywalker · Post by **skywalker** » Thu Sep 26, 2013 2:52 pm

Having the latest board tech is good but...

From my experience in racing, the most important thing we can do is actually RACE!

Personally i think the kite fleet here would benefit from some quick and dirty races on whatever boards we can get our hands on.

I'm down for a race this weekend if there is wind.

thankgodiatepastafobreaky · Thu Sep 26, 2013 7:54 pm

computers aiding the foils for the marked improvement and victory by Oracle??
http://www.sail-world.com/index.cfm?nid=115070

Moderate Wind Mateo · Post by **Moderate Wind Mateo** » Thu Sep 26, 2013 9:37 pm

Wow, sour grapes.

helimarine · Post by **helimarine** » Thu Sep 26, 2013 9:54 pm

I have been kiting for about 6 years but have been riding a foil (we call it airchairing) behind a boat for many more years. I have always wondered what it would be like, or if it is even possible to ride the air chair being pulled by a kite. With the airchair you are belted in around the waist and your feeted are cinched tight into boots with velcro straps. This allows you to have very good control of the foil and more importantly prevents you from ever being nailed by the foil. My foils are aluminum, very heavy and the trailing edges of the wings are very sharp. They would easily decapitate you if hit by it at any speed. Once you are up on the foil behind a boat there is no pull on the bar. You can literally hold onto the bar with one pinky finger forever. Most of the crashes occur when trying to learn the sport occur from bringing the foil up too close to the surface of the water, at which point the foil will stall and slam you back down to the surface, where the board prevents you from going under. I think the whole concept of mixing foils and kites has huge potential. Watching the America's Cup blew me away.

thankgodiatepastafobreaky · Thu Sep 26, 2013 10:20 pm

yes I'm sure you could use the air chair with a kite. I think there was one 2 years ago in La Ventana.

I was hoping that racing with the foil would make the racers safer after getting nicked by the race fins a few times at low speeds. But it sounds like it will be even more dangerous! and racers could be going even faster! Yikes.
Kiters will need full kevlar suits for learning to foil and race. ??

Laird Hamilton on the air chair : @13 min in.
http://www.youtube.com/watch?v=gBCQE7DAhg0

thanks for sharing helimarine.

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