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Fast wave hydrofoiling.

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plummet
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Re: Fast wave hydrofoiling.

Postby plummet » Tue Jan 15, 2019 10:47 pm

I'm actually finding this discussion really useful. Lots of different oppinions and ideas. Its all good.

Slowboat. I'm not trying to ride the wave like a surfer. But I am interested in riding it. Granted the clean waves are way more fun on a surface board for me at the moment. But that location has a lot of lumpy waves that are pretty average to ride on the SB but may be awesome on the foil if i can crack the code!

DRSurf. This location is not the prevailing wind angle so it would be very hard to invite dudes to ride it. You might get an opportunity once a month for a day or two. Borroing and using other foils isnt an option here because of the risk of damage and this location is hardcore for standard boards, boulders, cliffs, wind shaddows, cross off. Most foilers wouldnt even consider riding there. Maybe i need to start up a convo with the jshapes or Armstrong foil boys to can see if they are keen to come down and school me on how to ride big fast cross off waves?

Peter,

I definately feel more lift from bigger waves. Not so much on small waves. But the big waves have a definate marked increase in lift when they hit. Maybe 50% to 100% additional lift.
Perhaps it is the change in flow/speed of water much like ridge lift that the glider experiences? Like a wind gradient change? Like the different between kiting up/down hills compared to Flange.

Using your glider analogy. You have adjustable stab trim and can trim the glider for zero lift at max speed when needed. However with the foil you set the stab trim to provide the best set position for a variety of speeds. When you go faster speed than what the fixed aoa is set for you will get more lift than wanted. Imagine flying your glider on the with non adjustable trim. At some speeds the trim would be too shallow and some not shallow enough. Why is it any different on the foil?

Correct me if i'm wrong. But i am not aware of any foil that has zero stab aoa? all have some. This means all foils will to some degree have increase lift as speed increases. A well set up foil will run the fair range of its speeds without the rider noticing that additional lift much.

I do like the idea of a fat wing that with a low stab aoa set up to slow down acceleration while not providing too much lift.

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Peter_Frank
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Re: Fast wave hydrofoiling.

Postby Peter_Frank » Tue Jan 15, 2019 11:43 pm

You are right, probably most foils have a tad of negative stabilizer lift even when front wing is riding at zero lift angle of attack (which is never zero degrees btw, but unimportant for the discussion).

So it could be that some has so little rear stab negative lift, that you hardly notice lift changes when speed changes, whereas others got more negative lift so it might be violent when changing speed ?

As most riders use the default settings, this could be the reason why we got many different opinions on this, I think.

Also, in most cases (but not all), when going faster, you need (or get even when not desired) a lot more kitepull, and riding on the typical 90-100 cm masts, it means the kitepull delivers increased forward force thus quite a lot of downward pitching moment on the wing because of the lever, which might often counterbalance the negative lift from the stab, thus in total giving very neutral hydrofoils, unless you got too much negative stab angle of course.

Agree, really interesting thread :naughty:

8) Peter

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Re: Fast wave hydrofoiling.

Postby drsurf » Wed Jan 16, 2019 3:25 am

plummet wrote:
Tue Jan 15, 2019 10:47 pm
I'm actually finding this discussion really useful. Lots of different oppinions and ideas. Its all good.

DRSurf. This location is not the prevailing wind angle so it would be very hard to invite dudes to ride it. You might get an opportunity once a month for a day or two. Borroing and using other foils isnt an option here because of the risk of damage and this location is hardcore for standard boards, boulders, cliffs, wind shaddows, cross off. Most foilers wouldnt even consider riding there. Maybe i need to start up a convo with the jshapes or Armstrong foil boys to can see if they are keen to come down and school me on how to ride big fast cross off waves?
Hi Plummet.

Another simple answer, connect up with some foilers in other parts of NZ you can easily travel to and ask if you can have a try of their various foils. I know I'm always happy to offer another foiler a go on my gear.
What I'm getting at is that you need to widen your foil experience. There could be something much better out there for you but going through analysis paralysis on a forum won't find that. Forget AoA, lift and trim balance etc, try other foils! Skilled foilers have put in thousands of hours of testing, rider feedback, advanced flow testing and high tech manufacturing effort to produce some truly fantastic foils. You need to try them :thumb:

What have you got to lose? If your own foil turns out to be best, great, thats validation of your own product. But if you find foil/s that transcend everything you've experienced ... thats good too.

Have fun, Dave
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plummet
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Re: Fast wave hydrofoiling.

Postby plummet » Wed Jan 16, 2019 6:06 am

drsurf wrote:
Wed Jan 16, 2019 3:25 am
plummet wrote:
Tue Jan 15, 2019 10:47 pm
I'm actually finding this discussion really useful. Lots of different oppinions and ideas. Its all good.

DRSurf. This location is not the prevailing wind angle so it would be very hard to invite dudes to ride it. You might get an opportunity once a month for a day or two. Borroing and using other foils isnt an option here because of the risk of damage and this location is hardcore for standard boards, boulders, cliffs, wind shaddows, cross off. Most foilers wouldnt even consider riding there. Maybe i need to start up a convo with the jshapes or Armstrong foil boys to can see if they are keen to come down and school me on how to ride big fast cross off waves?
Hi Plummet.

Another simple answer, connect up with some foilers in other parts of NZ you can easily travel to and ask if you can have a try of their various foils. I know I'm always happy to offer another foiler a go on my gear.
What I'm getting at is that you need to widen your foil experience. There could be something much better out there for you but going through analysis paralysis on a forum won't find that. Forget AoA, lift and trim balance etc, try other foils! Skilled foilers have put in thousands of hours of testing, rider feedback, advanced flow testing and high tech manufacturing effort to produce some truly fantastic foils. You need to try them :thumb:

What have you got to lose? If your own foil turns out to be best, great, thats validation of your own product. But if you find foil/s that transcend everything you've experienced ... thats good too.

Have fun, Dave
Oh I will try foils whenever I can. But life is busy at the moment and there are many other fish to fry as well. So traveling to try other foils isn't an option. I also enjoy the engineering and design side of building my own gear. What may be over analysis for you is adding to my knowledge base for future builds and enjoyable for me. Equipment aside there is still the challenge of riding these types of conditions. From what i get out of this discussion is that there are very few people going out in this stuff and current surf designs are catering to smaller slower waves. So we have a knowledge gap of what equipment to use and actually how to ride waves.

Keep on with the ideas. i'm loving it.

Side note doesnt anyone else feel a market increase in lift on waves/swells?

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Re: Fast wave hydrofoiling.

Postby slowboat » Wed Jan 16, 2019 8:32 am

Yes, definitely more LIFT on bigger, faster waves. I have said this on several threads including this one. when I get in waves which are bigger than I can comfortably ride, the difficulty I experience is not from the speeds or angles, it is from too much lift. My brain yells at me “more front pressure “ and “ more back foot pressure “ at the SAME TIME and right before I breach and crash. That is why I think as the waves get faster, the wings have to get smaller. The ideal foil for a 1 meter wave should not be the same as the ideal foil for a 2 or 3 meter wave, in my opinion.

I am very surprised others don’t experience this.

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Re: Fast wave hydrofoiling.

Postby plummet » Wed Jan 16, 2019 10:44 am

slowboat wrote:
Wed Jan 16, 2019 8:32 am
Yes, definitely more LIFT on bigger, faster waves. I have said this on several threads including this one. when I get in waves which are bigger than I can comfortably ride, the difficulty I experience is not from the speeds or angles, it is from too much lift. My brain yells at me “more front pressure “ and “ more back foot pressure “ at the SAME TIME and right before I breach and crash. That is why I think as the waves get faster, the wings have to get smaller. The ideal foil for a 1 meter wave should not be the same as the ideal foil for a 2 or 3 meter wave, in my opinion.

I am very surprised others don’t experience this.
I think very few people are riding bigger waves, therefore, they don't experience the additional lift. Though it is true that the bigger the wave the faster it goes. There are definitely faster and slower big waves or more accurately waves that provide a significant increase in lift and some that don't. Perhaps big lifting waves are very location specific? I'm not sure. Most of the people in this thread admit to not having the chance to ride these types of waves. The more i think about it the more i am convinced that it the change in water gradient flow change that causes the extra lift. You have the foil positioned for water flow at horizontal then all of a sudden the flow goes uphill. The foil is now in a lifting position in relation to the water flow and boom. You are driven out of the water. I agree with you. Riding head high plus is a very different and requires a different set up and skill set.

Have you adjusted your stabilizer aoa? As Peter states, most riders just use factory settings and do not adjust the stabilizer angle as they assume it is perfectly optimized for all conditions. Often they opt to buy and sell many foils until they find one with a setting they like. When in reality you can change the performance of any given foil dramatically from extremely lively minimal front foot pressure to heavy front foot pressure and very stable with a 1.5° change of stabilizer angle. Its as simple as slapping some duct tape under the stabilizer and testing.

I suggest you try this for on your surf foil. I guarantee a little bit of duck tape will change and potentially improve your big wave riding experience. Side note. As the stab angle reduces your foil will have less front foot pressure and become more lively and less stable. But you can quickly stomp on the nose and dive the foil at speed and counteract the extra lift in the wave. This is the reason I wound my aoa back. To counteract the dramatic increased lift on bigger waves. I can now be going at warp factor 9 and at a whim and moments notice drive the nose into the water and or dive steep on the wave face.

Its a balancing act between liveliness and stability. I think i've gone too far and have lost too much stability. I might have to tweak the aoa back up a bit.


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Re: Fast wave hydrofoiling.

Postby TomW » Wed Jan 16, 2019 3:55 pm

I´ve only ridden head high ( barely) in cross-onshore in brazil. On a river mouth there was long faces and i was doing 35km/hr to keep up with the sections that were breaking.
Plus i was doing a lot of overtaking shoulder high waves and riding them. They were relatively weak waves. The river mouth was steeper wave.
I´m on Moses 633 wing. 75-76kg

There are a few things going on, I think.
1. I only have too much lift when i am overpowered on kite, with kite high.
2. Yes the water flow changes a lot as you overtake or get on a wave- Coming over the backside you have to lean forward then as you come down the face keep leaning forward ( but your brain is telling you to lean back because your are " falling"). then as you hit the bottom and flatter water you have to lean back to neutral position and set your bottom turn.

So my hypothesis is that the comment that you have to lean back and forward at the same time is actually 2 parts of your brain telling you two different things- One of them is " wrong".

Ive found the 633 to be plenty fast for our shitty windwaves and fast moving wind swell, but it goes really slow too. But you have to control that speed...

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Re: Fast wave hydrofoiling.

Postby slowboat » Wed Jan 16, 2019 4:58 pm

TomW wrote:
Wed Jan 16, 2019 3:55 pm
I´ve only ridden head high ( barely) in cross-onshore in brazil. On a river mouth there was long faces and i was doing 35km/hr to keep up with the sections that were breaking.
Plus i was doing a lot of overtaking shoulder high waves and riding them. They were relatively weak waves. The river mouth was steeper wave.
I´m on Moses 633 wing. 75-76kg

There are a few things going on, I think.
1. I only have too much lift when i am overpowered on kite, with kite high.
2. Yes the water flow changes a lot as you overtake or get on a wave- Coming over the backside you have to lean forward then as you come down the face keep leaning forward ( but your brain is telling you to lean back because your are " falling"). then as you hit the bottom and flatter water you have to lean back to neutral position and set your bottom turn.

So my hypothesis is that the comment that you have to lean back and forward at the same time is actually 2 parts of your brain telling you two different things- One of them is " wrong".

Ive found the 633 to be plenty fast for our shitty windwaves and fast moving wind swell, but it goes really slow too. But you have to control that speed...
Your hypothesis may be correct but I should clarify my comment. In my early wave foiling days I noticed that most of my crashes were due to back wing breaches as I was catching a wave or turning at certain angles. So I learned to remind myself “more back pressure” in those situations and back wing breaches got much less frequent. We all know the situations when we have to tell ourselves “more front pressure”. So fast forward to the present and as I try faster (higher pressure?) waves, I experience needing both more front and back and subsequent crash hence my conclusion that I have too much lift since obviously I cannot do both. Or maybe I just need more experience 😀

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Re: Fast wave hydrofoiling.

Postby plummet » Wed Jan 16, 2019 6:43 pm

Slow. I did a lot of venting the rear wing in the early days exactly as you describe. The answer for me the wave with the mast deeper in the water. Then you can take the drop without venting the wing. Ideally a longer mast is required for steeper days to keep the rear wing deep enough. I'm stuck with the 90cm so the only option is to go deeper. Once you negotiate the drop then you can pull up a bit more mast height.


And yes taking the drop on a hydrofoil and pitching the nose down stomping on the front foot and leaning forward on a steeper face is a mind f***.
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Re: Fast wave hydrofoiling.

Postby juandesooka » Wed Jan 16, 2019 7:18 pm

plummet wrote:
Wed Jan 16, 2019 6:06 am
From what i get out of this discussion is that there are very few people going out in this stuff and current surf designs are catering to smaller slower waves. So we have a knowledge gap of what equipment to use and actually how to ride waves.
Agree about not many people going out in this stuff. And those who do, most are probably aiming to do significantly different riding style than you. Meaning most of this discussion is pointless, as we're all just talking about our own personal experiences in isolation,but thinking we have some common denominator. ;-)

Regarding surf foils, there's a wide variation in designs aimed at specific needs. Consider that performance surfers will have numerous boards for varied conditions, a sup for tiny waves, longboard for small clean, fish for small mush, shortboard for everyday decent surf, then a big wave gun for the xl days. Just as in surfing, you will not get big wave performance on your fish, I suspect you may be expecting a bit much for your single do-everything design. A subaru station wagon is a great all round vehicle but it won't win a formula 1 race nor the Baja1000.

This is a helpful comparison chart for surf foils across brands: http://www.mackiteboarding.com/news/let ... hydrofoil/
But you'll note top speed is 18-20 mph and none are rated as for high speed. As you say ... the market is mainly aimed at slow waves. (probably because in faster waves, most surfers will surf!)

This page expands the discussion to include kite oriented foils, trading speed for lift
http://www.mackiteboarding.com/news/201 ... ical-uses/

As an example, slingshot's h3 wing is described as specifically designed for tow-in surfing (and in looking this up, see it's on sale for $99 at mackite....there's a cheap experiment for you maybe http://www.mackiteboarding.com/2018-sli ... e-h3-wing/ )

For performance of foil wings in larger surf I think you'll find better answers in the surf foil community than kite foil. In particular those who focus on tow-in surf foiling. That seems the closest to what you're trying to do (though also rare) -- youtube searches, forums, etc, may uncover some tips. EG Kai Lenny and a handful of others have posted session videos attempting to foil bigger waves.
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