I like the idea of adding more curve to the template as a means of moderating and smoothing out the onset/release of the lift. What you’re doing kinda fits the template of the board you’re using.
Okay, so I’m following along with intent interest at this entire thread with the intention of making a foil myself. However, I’m stuck on the part where you attach the foil to the keels. I’m guessing this requires a die and tap set to make threaded holes in the keel in order to attach the foil. I haven’t gone through the process yet but it seem to me that the attachment of foil to the keels seems very weak. Any deviation of measurements of the holes could create a weak point between the keel and foil. Is that it? Screw the foil into the keels and hope it holds? I know you’re out of town so somebody else please chime in. Has anybody done this yet? It seems very weak with a thin margin of error on dieing and tapping the thread holes in the keels. What if I glassed the keels onto the foil and then attached the entire combo into the fcs? Any opinions/feedback is appreciated.
Surfoils already said how he did it: position the foil over the strut and drill through it.
I remember when we were learning vacuum bagging and veneers from Greg Loehr. A lot of us (myself included) went back-n-forth before we did any of them with all the problems we thought we’d run into. But in the end it was just like he said: what you see is what you get and it really is just that “simple”.
I’ve never had a problem getting a veneer to turn out, and upon reflection I’m beginning to suspect the same thing may be afoot with the foils. Then again, I am that fool who goes where angels fear to tread.
Hope you have a great trip w the boys. Thanks again for sharing. I would’ve gone on a very different path w/o Your insight.
Couldn’t help but check in before I go.
Here’s an easy way to get the connection between the foil and strut.
You need to get this done first before you move to the board and mark out where the plugs go.
First place your 2 struts on the side lines , pick an arbitrary position a few inches in from both ends.
Mark either side of both strut positions with tape.
Pick two points where to drill the holes, I made it nice and even so that its exactly 2 1/2 inches between the hole centres. Drill the holes in the foil. Countersink if that’s your choice.
Grab the top of the strut and mark out 2 points exactly 2 1/2 inches apart to match the holes in the foil.
Maybe use a fine drill bit and a drill press to ensure the holes line up.
I’ve done dozens of struts like this and as long as you’re careful it works out every time.
Once you’ve got the struts screwed in you can take it to the board and in a similar fashion mark out where the plugs go.
Simple stainless screws are all Ive needed because all the forces are up. I’ve had thousands of waves and never lost a foil with just 3/4 inch screws but you guys might have a better way.
In 1991 I got excited and stripped the glass off an old windsurfer. A quick reshape of the remaining foam got me a 6’9" board that has been a twin fin, then added third fin, then had a large single and then layed around the back yard for years.
I just got excited again, thanks to Mr. Surffoils, so have removed all the fins and about to get some ply for its new foil.
To be continued…
Thanks so much for this thread. Have made a couple of foils, one on a prone board and one for tow in with hilarious results. Still more r&d I thought! But then this comes along. STOKED & thank you again for sharing.
Enjoy your trip. Slanj
Going back to basic board design - with a hard corner on a tail shape when the release occurs it will be abrupt and pivoty. So when we want to avoid that level of drama we add curve. The dominant characteristic of a fat McCoy-style round tail is that while they’re easy to turn with the appropriate fin selection they never do actually break free on their own - it’s all control.
The whale’s tail is an articulated and adjustable wing that is actively controlled from very rear of the tail - not a passive lifting surface that’s mounted at or near the center of mass. These lifting surface we’re using operate from a static position at their mounting points and on that basis is more passive - you have to move the board to change the wing’s relationship to the energy.
So I look at the short chord and sharp release points of the SUP wings and it’s apparent that they can’t be that stable without a very constant and active control effort. By the same token I wouldn’t anticipate that a long chord egg shaped wing that might fly closer to a stable line on its own and with minimal input would break off that line without a tremendous amount of input.
Keep in mind the foils you are building in this thread are for lift at relatively low speeds.
Lift quadruples when speed doubles.
What I’m aiming at are the really low speeds that nobody else is riding. I’m happy to leave the pitching waves and the flying guillotines to others.
That’s me telt then eh?!
Hey SGO, that how I do it. 8 plugs at once.
I even use 8 R (rail) plugs because the cant angle fits better that a C plug on a concave hull.
And now it’s Ready to surf any wave any where.
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I’m lagging because I’m building foiled struts out of G10 and aircraft ply. Time consuming. I am working on it, though
I went with the suggested 10mm polypropylene, shaved the bottom down to fit plugs, and cleaned up leading and trailing edges.
Cost $25.
Race you to the water gdaddy 
THats very quick !
And there’s no need to foil those struts into blades, just round the edges and it’s fine, most of the length won’t be in the water when you’re foiling.
How long are the struts ?
So you’ve booking this in as $25 for a foilboard ? Nice one !
Plugs, struts and resin all up about $100 for the set-up. All the rest was laying around.
Not a pretty board but will soon let me know if I’m cut out for foiling or not !
Struts are rounded leading edge and a bit of a taper on the rear.
Had some 2 oz. cloth so put that on the bottom of the foil.
Hope you’re not offended by the label on the foil
Did you end up heading towards Bells on your trip, 'cause if your are you can take this for a spin and show me how it goes ?
cheers.
Looks good SGO !
We Went North, then back South because one son forgot his wetsuit…D’oh !
And then North again.
What’s you area on that foil ?
A full foil has a lot of lift and you should feel it instantly so please take a whole lot of small waves to start.
I’m guessing you’ll see how incredible the lift is and quickly start cutting out area to modify the lift.
It is amazing just how much grunt it has even on small waves,