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Messages - Dontsink

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Foil SUP / Re: Mast position fore/aft on the fuselage. Care to speculate?
« on: February 06, 2021, 01:50:37 PM »
I think it should affect the directional stability of the foil ,the yaw axis.
Most tail wings have a bit of curve (vertical stab effect ) and even if they are fully flat they have drag that will tend to align the stab behind the mast.

How this changes the foil behavior in pumping or turns i have no idea :)
I know it makes some foils not suitable for some boards, because the boxes will be to far fwad or back.
The Takuma LOL has the front wing pretty far in front of the mast compared to a Naish foil.With most other foil brands somewhere in between.
Manufacturers should start giving some info on this, something like " xx size wing has the Center of Pressure xx mm's forward from mast plate front screws"

So you could get an idea of foil/board compatibility

I am not able to get on foil below 10kt either,and being realistic 10kt average means 8-12kt gusts and lulls.
But i like foiling with the 6m wing  in it's low range when it is steady, it's a very Zen experience with the flat water and the foil gliding so smoothly.
Kinda hypnotic :)

In winter i get a lot of 20-30kt days.
Above 25kt i am in survival mode with a 4m wing,i have to umbrella it so much that it gets difficult to keep some forward drive.
I will probably get a 3m for next season.

My biggest gripe when it gets to 25kt and gusting is that when you fall the wind easyly picks & flips the board and it can land anywwhere, on me or the wing...i started to use a bike helmet on those days and now i always use it.It is warm :).

Foil SUP / Re: Foilmount shims
« on: January 20, 2021, 10:51:13 PM »
Looks pretty good!.

The shim angles can be measured with trigonometry or with an angle measuring app de for the phone.

If the angle is the same as what you had with the hotel cards it will ride the same,just a better connection.

Wingsurfing, Windfoiling, Wingfoiling, Wing SUP / Re: Axis Foils
« on: January 19, 2021, 09:10:10 PM »
IMHO what Kai might have meant was that you do not flex your knees on a foil as much as when on a planing surfboard.But shortboard surfers flex and extend a lot,all the time.
If you google "kai lenny foiling"-images you can see that there is always quite a bit of bend in his knees.

Even Alan Cadiz ,blasting on a wingfoil in protected water has some very noticeble bend in his knees (minute 2:06 )

But i think i get what DW meant because on foil it feels good to use a bit of a more rigid leg stance,it adds a very stable feeling in pitch.

In the vid you were just doing what the situation demanded with the foot position you had, it looked quite good actually :)

I love this!  thanks for the PDF link by the way, I've saved that for future reference.

Back the point brought up by SanO - I'll say that I haven't noticed a difference between the standing deck angle during flight with several different boards for which I KNOW there is a difference in the angle between the foil and the deck.  However, I have noticed the difference during wave take-off.  I know you don't care about wave count or how it feels to catch the wave - but I do!  I'm pretty sure that for me, once I'm up in the air - the board basically doesn't matter besides the weight.  For me that includes the precise angle of the deck to the foil - I don't think it effects my riding experience.

I've noticed the biggest differences between boards is apparent at the initial wave take-off and acceleration.  It manifests in where my weight needs to be to keep things in control.

Best: my foot position and weight balance fore-aft matches for all three important phases - maneuvering for take-off, paddling for take-off, and flying.

Realistic: my foot position and/or weight balance fore-aft changes through these three phases.  In reality, I get to know the board and the foil characteristics as well as various types of wave takeoffs and manage this through feel.  But there are a ton of combinations to manage and I'd rather not take the first half hour of every sesson blowing waves until I get the right feel.

PS. from having spent just a few days at SanO - you guys down there are totally spoiled.  That's about the most user friendly wave I've ever encountered (I rode it both overhead and piddly small).  For those of us in more challenging waves, takeoff is huge

I agree with this, a one degree mast shim makes a big difference in how the board behaves on
take off but for me it is negligible once in flight.

And the take off is THE maneuver that makes or breaks my sessions,what comes after is the icing on the cake :)


I also don't argue with folks anymore about what happens when you ride a wave. Thinking this is a gravity sport where you accelerate by sliding down the wave requires a mindset I don't expect to alter. I'd think the first time you see someone accelerate to 20+ mph while going backward up the face of Peahi would kill that notion, and the idea of foiling for a mile because you slid down a three-foot wave should seal the deal. But no.

Simplified explanations sometimes take a very strong hold in people's minds, digging deeper often involves hard work and not so satisfying and clear cut conclusions.

How foils really create lift is a good example.
The widespread "Sesame Street" explanation of fluid particles separating at Leading edge and happily reuniting at the Trailing edge is simple,endearing and ... false.
But digging deeper is kind of frustrating because there is no complete explanation,  we can design wonderful lift creating surfaces for just about any application but nobody really understands fully how they work.
I have been flying airplanes for a living since '98 and when i say i don't really know how they manage to stay aloft i get funny looks, if i say nobody really knows people get offended  ,fellow pilots the most :)


Yes, mast shimming depends on whether the board has tail rocker or not, and how much. I had to throw a 1o shim under the front of the mast on my previous board to get to to fly level instead of nose down, but my next board from the same shaper sets the fuse perfectly level with the deck, so no need to shim that one. Basically shimming the ride angle of the board when the wing is flying level in the water is what you're doing.

Actually, you've doing a bit more than that. You're also setting the AOA of the foil--both wing and stabilizer--when the board is in the water. To see what that affects consider an extreme in both directions. Say the foil is pitched down 10 degrees. Obviously draggy as hell, but it also pulls the board down onto the water when you're moving forward. You'll have your work cut out for you trying to get the wing to fly--you'll have to stand on the tail like crazy. And when the AOA reaches zero degrees it will explode out of the water. Now pitch the wing 10 degrees up. Still draggy, but now it's trying to lift the tail. Get the board up to speed and it will come up easily--and stall.

Yes, the AOA for takeoff (for a given foil) depends on the boards trim on the takeoff "run" and the angle at which the foil is held by the whole support system (rocker,mast,fuse angles).

Ideal board trim position is whatever provides lowest resistance to forward movement .

But the foil system angle to the board we can alter at will via mast plate shimming.

This is just my experience but i think that using the same foil i prefer bigger initial AOA for winging than for surfing.

I think the reason is the very different way we accelerate to takeoff speed with wing power vs wave power.
With wing power the acceleration is very progressive and under our control,like stepping on a gas pedal, with wave power this acceleration is like lighting a rocket. From zero to full blast in a blink.

There is also the fact that when paddling into an unbroken wave you are always battling to keep the nose from rising (pushing it through the ledge).

Anyway, my point is this:
 If your board+foil combo is giving you trouble when getting up on foil experimenting with mast plate shimming can be a very effective solution with little work or money involved,and fully reversible.

Right now this initial AOA is set by the manufacturer, whatever they thought was optimal .If you are mixing board and foil brands and practicing different foil disciplines this AOA can be a hit or miss thing, but easily tweaked via mast plate shimming.

I bought the carbon foilmount to build a board with an idea I had that turned out to be more or less what Gong did with their new inflatable. I was going to build a rectangular carbon box around an XPS core with top and bottom handles, foot strap inserts, and a foilmount stuck on the bottom and then wrap it with a lightweight shell that is the floaty parts of the board. A rigid, super strong core for all the stressed elements and super light shell around it. I might still do it some time but I have all the wizardhat stuff sitting at my shop. Unfortunately, all that is in Hood River and I'm in La Jolla.

I just ordered the shim set and hardware so I can get rid of my bogus shim. Thanks for the inspiration.

Modular boards are something that could be really interesting.
I would like some manufacturer to make a strong carbon box+core like you describe as the system "base" and sell softboard Wing,SUP and Surfoil bodies to fit around it.
We only need serious stiffnes where we stand.

Yup, the wizard hat hardware.
But mind you, i have not used it, just liked the concept

10mm is a big shim!, nice to know that it works OK, what worries me with bigger angle shims is not the shim(works in compression only) or the screws but the angle you are forcing on the sliding inserts inside the plastic box rails.They will have all the pressure concentrated on the front or back end of each slider, not ideal.
But if yours has not gone bust i guess there is a lot of leeway.

Foilmount sells hardware that will work up to 3* shim ,they have a swivel that will always align the surfaces nicely.
Anyway, i think 1* is a huge change ,3* is mostly meant for surfboard to foilboard conversions where the board has "surf" rocker at the tail.

My Gong has full flat bottom in the back half ,i did try shimming the stab (and different stabs) but in my case it did not help at all.Shimming the mast did the trick.

For comparison,my  Armstrong foils work perfect for prone surfing sans mast shims but do not rise as nicely as the shimless Takuma when winging.

Every manufacturer is setting different angles on their foils, add different rockers and volume distribution on boards plus different disciplines and it can get confusing and frustrating :)

I have a Takuma LOL 1600 full carbon.I love it for winging but i could not make it work for prone foiling.
It felt super draggy paddling into the waves and it would rise like a psycho when dropping in.
I thought it was too big for my 75kg, or that my board (Gong Matata EPS 5.0) had the boxes too far forward for this foil.I had almost given up on surf foiling it.

But reading about how the Kujira riders are shimming their mast plate for increased angle of attack on wave entry with great results made me think that maybe my LOL needed exactly the opposite.
So i made a 4mm epoxy shim(with some carbon to keep it from splintering) and screwed it on for todays session,thick side at the front to reduce angle of attack when paddling in.

Wow, worked like a charm.Easy paddle in on foamies or unbroken waves, nice controlled rise.Perfect :)

For winging i like it unshimmed, as the rise on foil is very progressive compared to surf foiling.

This mast plate shimming is a huge factor , so if anybody is having trouble with a particular board/foil/activity combo i encourage them to experiment with this before spending money on stabs,foil wings etc...

3 to 4mm has a huge effect, i would not try more than this as you would need longer screws and even with this the angle would put stress inside the rail inserts. Foilmount makes swiveling hardware that allows for big angles if needed.

Wingsurfing, Windfoiling, Wingfoiling, Wing SUP / Re: Axis Foils
« on: January 10, 2021, 03:05:18 AM »
Where can you order those Kane tails?.
I might buy one for a Takuma LOL.

Clever marketing if nothing else. There are some radical designs there, but mostly it's relatively minor variations. You could take every board a builder/designer like Dave Kalama or Mark Raaphorst and give it a different name instead of just dimensions and suddenly you have 40 recognizable sub-brands that people can talk about.

There's a lot to learn from watching how Gong and Blue Planet market their products. Both companies are too small to have a big marketing team using collective knowledge and marketing data to drive their business, but they've been at it long enough to have tried stuff that resonated with their target market.

These are relatively simple products to design and prototype, so the gap between design and testing is short. The real test will be what works in the market--these boards will be winnowed down to the winners, and winner means the ones that get bought. Giving each iteration and easily relatable name even though it will create confusion in the marketplace (which one should I get?) it's much easier to optimize. There isn't an easy way to optimally market just by size and intended function.

Smart people.

I might be wrong but i would say Gong sells +100 boards for every BluePlanet.
It is a big operation.

For those light wind gybes i find it helps a lot to put the wing flat overhead as soon as you enter the turn.

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