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Why don't they just put a flange on the foil so it doesn't bottom out in the box but rather spreads the load over a greater surface.
Alex Udin of Phantom said that Patrik D. requested they not use a flange for the same reasons as DarrylG mentioned
www.windsurfing33.com/forum/viewtopic.php?f=42&t=120891&p=863756&hilit=Patrik#p863756
I use both flanged and non-flanged foils in deep tuttle boxes.
Yes, the big "beak" flanges that Moses provided on their 101 and 111 masts were famous for denting the board when users rocked them to remove. Moses has ceased making those masts. They now make flange-less masts. My Race 105 is flange-less.
I also use the small flanges found on LP and Slingshot foils. I have not found them to be any problem with denting the board. I like how they set the mast to board angle with no variation. Even a board with some centerline V will show an infinitesimally small gap along the side of the small flange. No biggie.
I use a lp windfoil in an old starboard 161. So far so good the fin box is hanging in there. After seeing the Starboard race foils chew out fin boxes I figured a flange was a must if I want to use a older formula board as a stepping stone into foiling.
I agree with WOH
the tapers work for normal fins, not for foils. The loads need to taken on top of box
No, I disagree with DarrylG. Since foil forces are ALL fore and aft and not much side to side like a fin, those tapers are CRITICAL since they carry ALL the fore and aft loads along their entire curved surfaces. When Tuttle designed the box, he intended for full and intimate contact to the tapers, both ends. And he did this long before anybody even thought about foils.
Tuttle never intended to have any contact inside the top of the box. This is why you see deep tuttle tops with varying heights. Recall all those formula fins. It's all taper.
Custom foilboard builders use deep tuttle boxes that are taller on the inside than any expected foil deep tuttle top, intending to ensure a gap between the top of the foil and the inside top of the box. They intend for all the fit to be to the tapers. That's how Tuttle designed it and how formula boards for the last 20 years have implemented it.
Flanges are nice, but it's the for and aft tapers that matter.
When I first purchased my no-flange AFS-2 foil from Sailworks three years ago, Bruce Peterson was adamant about not changing or sanding the deep tuttle top. Fit it in there. Use McLube if necessary and rock that puppy into place. After tightening the screws, keep rocking and tightening until it does not move anymore.
If you shim the inside to change the mast angle, you defeat the purpose of the tapers. That will destroy a finbox because shimming introduces point loads inside.
probably bad for the sport.
I've done hundreds of hours of foiling with flanged foils in unmodified boxes. Even shallow Tuttle using a DIY load spreader.
At the very least I'd like to see a small front plate like Horue and others use but ideally a plate which contacts the sides as well.
Personally I think that recreational foils will all be using a plate mount within a year or two. If the need to run a fin wasn't there I don't see why race foils wouldn't do it as well.
So much easier to tune the equipment to the sailor and conditions.
Of course they need to be tied to the top laminate just like any other foil attachment system.
Much like how foil boards really need some sort of stringer from the foil mount forward to the mast base. We've all seen pictures of formula boards break in half right between the front and back straps because of the forces put into them from foiling.
Reading all the the above about foil to board connection issues you can't help but wonder what will happen when the Olympic guys and girls really start to train on this gear hard, its a different level to weekend warriors, I think its a different level to PWA. Perhaps these things should have been solved before windfoiling became Olympic.
I don't image too many issues.
it will be starboard foil to starboard board. Most issues are with old style boxes
it's not really that complicated.
below is some info supplied with starboard foils. As it states, flat bottom for best support
There are two or three sources of deep tuttle boxes with greatly thicker sides and ends. I would presume the thicker ends would stand up to the concentrated stresses placed onto the tapers by the fore-and-aft rocking forces from foils. I bought the bullet and purchased a custom foil board from a long-time board builder in Hood River. They use a thicker-walled deep tuttle box AND add 16" long stringers forward to beef up the strength of the box to carry cantilevering forces from foils.
I believe that side to side forces on foil boxes are miniscule compared to the days of formula 70 cm fins. To go upwind and downwind on foils, you just tip the whole thing to windward or leeward and let the wing do all the work. When tipped the wing exerts a side lift as the sine of the tip angle. Yaw forces exerted by foil masts are, I believe, quite small.
You can flex a formula fin by hand but not a foil mast. Yet looking at video you can see foil masts bending along their length.
So I'd say the side loads are far higher on the foil.
I think I've bent aluminum masts in ways I couldnt even with a car. Sideways loads are phenomenal.
Remember the hysterics about numbers in the foil race classes?
www.facebook.com/mmenagen/videos/10158154533233604/
The loads of the fin box and foils are much larger that we have previously had to worry about.
Old FW boards fin boxes can manage the loads, but only if the head fits perfectly, which unfortunately is a bit random.
If there is any play at all, the fin box will collapse within hour of using a 95+ cm Vertical.
That said, we have used old FW boards for years with zero issues...
From what I can tell, all the dedicated Foil boards fin boxes are working perfectly...
Hi Everyone and hope you are all coping with the virus situation...
The foil boxes are a huge challenge partly because the design and construction of the cobra built boards use a box that isn't strong enough to support the load on the leading edge of the box. We have broken every box from several brands because the boxes are potted with a brittle resin that breaks out and then the foil point loads the very front and breaks the box. It goes against the Tuttle design and counter intuitive form an engineering perspective to support the foil at the top instead of the front face. This is also a challenge since there is seemingly no way to make this perfect with contact and mechanical support on two surfaces. However, once we started putting in 3d printed shims at the top of the base all the issues went away and the foils are much more locked in the board. This also gives the ability to change the rake bit which is super great. If anyone wants the 3d model for the shims let me know and I make them available via a printing service.
--cr
