Author Topic: Getting ejected out the front door...  (Read 17785 times)

tarquin

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Re: Getting ejected out the front door...
« Reply #75 on: January 25, 2022, 01:35:06 PM »
Yes. So many people fought cavitation. Who broke the speed sailing record by inducing cavitation with a wedge shaped foil. The Perigrine falcon is the fastest bird in the world. WHY ??
Multiple ladders just don't work in the real world.
 As far as surface erosion most of the offshore cats suffered massively from this. They couldn't understand why the foils failed all of a sudden. The last cup boats where having to do massive work to the leading edge after each race.
 Sorry after numerous beers no answers.
 Its no secret but most high speed and offshore foils are a mixture of metal(still don't know) leading and trailng edge, airex core inbetween. Then prepeg carbon. Baked in an autoclave. Sometimes over days. Every little thing is calculated. INEOs bought out the epoxy they found to be best. Not the brand just the type that company made so the others couldn't use it. Same with the carbon fibers. Just to give them an advantage!!!!
 We are where we were I don't know 30 years ago. The cycle will start again.

PonoBill

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Re: Getting ejected out the front door...
« Reply #76 on: January 25, 2022, 08:12:08 PM »
I gotta ask - this ventilation issue - I assume itís become more evident as people move to faster higher aspect wings? I know plenty of people that came up on axis gear (letís call it with low aspect wings) who didnít experience this issue before - or am I missing something?

Mostly just progression I think. If you're on low aspect wings you probably won't reach speeds where ventilation is inevitable. Some people probably did go faster and crashed and didn't know what to call it. You'll probably never ventilate in a wave, for the most part, you're not hiking out or yawing.

Any old windsurfer recognizes this cycle. For a long time, people were trying to make fins that overcame "cavitation" which was actually ventilation. Really fast windsurfers contact the surface of the water with a few square inches of board and fins that barely work even in a straight line--they are ventilating constantly. They don't turn until they slow down, which happens very quickly when they aren't applying full sail power. Then it was the kiters suffering, though they generally get to go faster before the wheels fall off the bus. Kiting is an aerial sport, in part because it's really hard to keep the board on the water.

Slicing something through the water at 20+ mph is a big problem, and the faster you go, the nuttier the physics gets. You are parting an incompressible medium that is a thousand times denser than air, using equipment that is about as minimal as it can be, with a control system that probably shouldn't work at all.

Crazy shit. What fun!
« Last Edit: January 25, 2022, 08:25:41 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

supmmmm

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Re: Getting ejected out the front door...
« Reply #77 on: January 25, 2022, 08:36:13 PM »
Haha - thatís great 😀🤙
Going west tmrw for a weeks trip snowboarding in Banff - will get back at this wing n foil stuff in the spring down in Hatteras. Actually picked up a surf board for the foil to play with as well.
Be well Bill - your feedback is much appreciated 🙏

Hdip

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Re: Getting ejected out the front door...
« Reply #78 on: January 25, 2022, 09:30:40 PM »
Mostly just progression I think. If you're on low aspect wings you probably won't reach speeds where ventilation is inevitable. Some people probably did go faster and crashed and didn't know what to call it. You'll probably never ventilate in a wave, for the most part, you're not hiking out or yawing.

Just to prove there is an exception to every rule. Prone foil,  low aspect surf wing, slow 1 foot waves. I sold a mast due to ventilation issues. A thinner mast has fixed the problem. Or maybe, it's a mast that has flex that has fixed the problem. Who knows.

supmmmm

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Re: Getting ejected out the front door...
« Reply #79 on: January 25, 2022, 10:35:57 PM »
Mostly just progression I think. If you're on low aspect wings you probably won't reach speeds where ventilation is inevitable. Some people probably did go faster and crashed and didn't know what to call it. You'll probably never ventilate in a wave, for the most part, you're not hiking out or yawing.

Just to prove there is an exception to every rule. Prone foil,  low aspect surf wing, slow 1 foot waves. I sold a mast due to ventilation issues. A thinner mast has fixed the problem. Or maybe, it's a mast that has flex that has fixed the problem. Who knows.

Would you mind sharing which mast you sold and what you went with instead for prone foiling?
I was thinking of maybe getting the 16mm axis mast for prone foiling.

tarquin

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Re: Getting ejected out the front door...
« Reply #80 on: January 26, 2022, 12:47:12 AM »
Really interesting interview and loads of info about IMOCA foils and the different approaches. To give you an idea of how complicated it gets.
https://youtu.be/3OaUEJG2RnE

Hdip

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Re: Getting ejected out the front door...
« Reply #81 on: January 26, 2022, 08:56:08 AM »

Would you mind sharing which mast you sold and what you went with instead for prone foiling?
I was thinking of maybe getting the 16mm axis mast for prone foiling.

When I was on full axis I had the 16mm mast and didn’t have the problem. I had a universal mast that was 19mm and had the ventilation problem. Since I was only on lift wings at that point and lift had come out with their current mast I just sold the universal mast and got lift. The lift is 14mm thick I believe.

Since I’m the only one of at least 5 guys down here that had the issue I don’t feel it’s fair to publicly name the universal mast. Like I said though. Exceptions to every rule. It really makes me think it’s a stiffness issue that’s the problem. To stiff can be bad in my mind.

The problem would repeatedly occur when dropping into a slow wave and trying to bottom turn, twist and drive to gain speed. So as ponobill said. Hiked over and yawing at the same time.

PonoBill

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Re: Getting ejected out the front door...
« Reply #82 on: January 26, 2022, 10:25:55 AM »
Yeah, I should probably have stated an exception for prone foilers, and Junya, Dave and Austin on SUP foils. I see the torque and lean angles these folks employ every time I surf foil. That's the outer edge of possible and probably a foot beyond the line.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Velasco

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Re: Getting ejected out the front door...
« Reply #83 on: January 26, 2022, 11:35:32 PM »
I think I am the guy that bought Hdip's 75cm universal mast.  I have proned foiled it in everything from knee high waves to well overhead (Takuma Kujira 1210/self made 14.75" G10 rear stab).  I'm 185# and I've never ventilated this mast.  In fact, I've gotten 5 for 1s, and cranked the hardest leaned out turns all on the same rides - so this mast has served me well.  I've also used it winging (but not much as it is a hair shorter than my preference for winging)- and I have not ventilated it at speed either.

I liked this mast so much I bought an 85cm version (and I'm waiting for a 68cm to prone during lower tides).  I have ventilated while using the 85 (with the ART999/420 on the Ultrashort fuselage) - but that was going faster than 25mph.  I need to use the Kujira on both the stock aluminum 85cm mast (I had to buy this to get the fuselage) and this universal and see if it is rider error or truly a thickness difference.  I haven't experienced ventilation on the stock mast - but then again I haven't used the Kujira on the universal yet.

So to convolute this topic even more - same mast cross-section, different uses, different results

tarquin

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Re: Getting ejected out the front door...
« Reply #84 on: January 27, 2022, 12:42:08 AM »
https://youtu.be/NefnpuxS2uM
 Had a talk with a friend that has done some IMOCA stuff. He said ventilation is normally caused down low by some sort of disturbance. Which is part of the reason for winglets,curved wing tips. What ever you want to call them.
 He doesn't foil and the foils that they use are different. But he had a quick look and thought this.
  Maybe its not the mast but a vortex being created by the fuse mast join or somewhere else. This would partly explain the different experiences from people. Same mast but different fuse/ foil setup. He said if you look at moth foils and the last Americas cup foils they have the central torpedo. This is to help prevent ventilation. Anywhere you have a join is a problem spot that could start a vortex and lead to ventilation.
 

tarquin

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Re: Getting ejected out the front door...
« Reply #85 on: January 27, 2022, 05:02:22 AM »
These guys were great during the last AC explaining things.
https://youtu.be/x_CzbAvQaZE

Hdip

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Re: Getting ejected out the front door...
« Reply #86 on: January 27, 2022, 07:03:37 AM »
I think I am the guy that bought Hdip's 75cm universal mast.

Yeah! I figured I was the problem here. Glad youíre stoked on it.

Fishman

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Re: Getting ejected out the front door...
« Reply #87 on: January 29, 2022, 11:14:40 AM »
https://youtu.be/mLFU7fQWXQs

Dig that. At the end he says he doesn't recommend sanding aluminum masts but who wants to try with a little matte clear poly or other matte paint?

Axis is anodized. Gong is painted and not glossy.

Windsurfers, who knew they knew stuff? 😉
This makes the most sense to me as a contributing factor, when we accidently introduce more low pressure on one side of the mast. How much of a factor... maybe more than we would think???
Waxes, nano coating, oils from you hands and uber smooth surfaces all push water away. Replaced by air, so yeah.
 Not sure of any other reason to not have the same rule to "aluminum" masts.  I suspect the only reason he may have not recommended sanding for aluminum mast, is  maybe for concerns of removal of the  protective anodized coating on most brands.

The paint coating on the Gong v2 aluminium mast even thought it's "textured", it is very hydrophobic. Even after sanding one of mine it remained hydrophobic until I got all the texture removed. The paints so thick it might be better to strip it chemically, then paint it, then sand. I'm only sanding my 95cm for now.

The parallel sides of the universal masts are plain ole not going to have as much low pressure at the same mast angle as the more hydro dynamic shape (except for the trailing edge which less likely to cause any control problem. Just maybe more drag which probably wouldn't matter for most of us.
« Last Edit: January 29, 2022, 11:21:26 AM by Fishman »
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clay

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Re: Getting ejected out the front door...
« Reply #88 on: February 12, 2022, 05:07:48 PM »
Bumping this thread to see if there is any new info?

I did quick test a while back on a new faster wing in lighter wind and ventilated at speed during a gust.  Immediately gave up on these wings until I find a solution.  So my interest is not face planting so I can actually give these wings a proper go and see how they ride when winging. 

Video I have seen it's the air getting to tail and the tail losing lift that causes the blow up, so maybe adding something to the mast or fuse can divert or clear that air flow to maintain altitude?

The other times I have mast ventilated is fully loading up overpowered harnessed in driving hard upwind and the mast cutting through some chop.

Never had it happen surf foiling, I have reached around 28mph in 10 foot surf and no issues.
Aloha, I welcome and appreciate all responses of positivity and good feeling.

YouTube: https://www.youtube.com/channel/UCOIE6FWr1SpWvbPJIIiEgog

Solent Foiler

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Re: Getting ejected out the front door...
« Reply #89 on: February 12, 2022, 11:40:53 PM »
Half an update...

We had a bit of a wind drought during January and I didn't get out for 3 weeks, but first time back I had another go on the Gong V2 mast (which was way worse than the Axis 19mm) and made it work! 'Surprised' was an understatement!

I consciously tried to drive laterally through my back foot and not force yaw through my front foot. Whether the time off made me more sensitive to what the mast was doing, I don't know, but I am happy with the outcome. I haven't tried it again since, so not counting my chickens as conditions play a part too, but it does look like this could be a case of being user rather than equipment issue.

What I don't understand is that I really tried previously to alter my technique to work with it, but without success, so what suddenly clicked, I have no idea. This sport keeps you humble...

(EDIT to say I've not tried the Axis mast again so update on that from me)
« Last Edit: February 12, 2022, 11:44:26 PM by Solent Foiler »
I'm 5'10", 66kg riding:
Swift Foil Boards custom 4'10 x 19.5" 35L
Gong Lethal 4'6 65L
Axis ART 799, 899, 999,1099, US fuse, 85cm mast
Gong Fluid L-S, XXL-S on 85cm and 65cm mast
Duotone Slick 3m, 4m, 5m

 


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