Sometimes I feel like there is an instability with a frequency of several Hz. I think may be a yaw wobble in the Armstrong mast. It seems stiff in other dimensions but out of water if you give it some yaw and let go it vibrates for ages at several Hz.
It seems to set in occasionally on a run, not all the time, and indeed I can repeat a run in the same stretch of water at same speed and it isn't there. it is almost as if it gets into a resonance. Anyone else experience this, and identified what starts it off and how to stop it
Yeah I experienced this with the 1325 on an 85 A+ mast (with 60 A+ fuse and 195 tail), especially during jibes and tacks. Not so much in a straight line. I thought it'd be a good light wind wing but it's not for me. I'm 82kg so presume that weight is a contributing factor. I spent about two months trying to dial it in--I initially thought that the wobble was a result of user error. Solution? Learn to use the 925 and/or 725 in light wind. Or... wait for the high performance mast.
IMO, the standard mast is not engineered to adequately accommodate the 1325 and 1525 for average to heavier-weight riders. I'd go further and suggest that Armie had the idea for those wings before exploring the possibilities of having a stiffer mast. I believe he's about 90kg so would presume that he, too, experienced some wobble.
Seems odd it happens some times and not all times, and for me occasionally in a straight line. I wonder if it depended on feet position relative to mast and applying a torque horizontal wit the board flat, rather than tilting board and keeping body in line with mast. Will do that more next time.
Select to expand quotepatronus said..
Seems odd it happens some times and not all times, and for me occasionally in a straight line. I wonder if it depended on feet position relative to mast and applying a torque horizontal wit the board flat, rather than tilting board and keeping body in line with mast. Will do that more next time.
If you're experiencing this with wings other than the two mentioned, I suggest you alter your feet position so that you have control on all three axes, whether or not your back foot is behind, on top of, or in front of the mast. FWIW, I have had no flex or wobble on all other wings that I've owned or tried, with the same fuse and tail setup: 1550V2, 1250, 925, 725, 1200V2, 950. The only exception is when taking the 925 or 725 through turbulent whitewater--but that's more to do with how the HA wings handle air bubbles.
Select to expand quotepatronus said..
Sometimes I feel like there is an instability with a frequency of several Hz. I think may be a yaw wobble in the Armstrong mast. It seems stiff in other dimensions but out of water if you give it some yaw and let go it vibrates for ages at several Hz.
It seems to set in occasionally on a run, not all the time, and indeed I can repeat a run in the same stretch of water at same speed and it isn't there. it is almost as if it gets into a resonance. Anyone else experience this, and identified what starts it off and how to stop it
Happens to me all the time when I reach a certain speed even with the 725 or 525. I love wings and fuse from armstrong but I think the mast is a bit too soft.(I use 72cm) Happens to me often before to catch a wave when I accelerate when I cumulate speed from the wing + speed from the swell. Happens just before to go in free fly to start to surf.
Also in the zones of turbulences sometimes I wonder if I tightened the screws because everything is "dancing" under my feet.
In the past with the soft mast/fuse (TMast) from Takuma (still more than the one of Armstrong) it was exactly the same and still more often. Even in the tacks at the start when you go upwind the mast was doing like a spin out especially with a big front wing. With a smaller one never during the tack; only in straight line for a certain speed.
Select to expand quoteSonsaleta said..patronus said..
Sometimes I feel like there is an instability with a frequency of several Hz. I think may be a yaw wobble in the Armstrong mast. It seems stiff in other dimensions but out of water if you give it some yaw and let go it vibrates for ages at several Hz.
It seems to set in occasionally on a run, not all the time, and indeed I can repeat a run in the same stretch of water at same speed and it isn't there. it is almost as if it gets into a resonance. Anyone else experience this, and identified what starts it off and how to stop it
Happens to me all the time when I reach a certain speed even with the 725 or 525. I love wings and fuse from armstrong but I think the mast is a bit too soft.(I use 72cm) Happens to me often before to catch a wave when I accelerate when I cumulate speed from the wing + speed from the swell. Happens just before to go in free fly to start to surf.
Also in the zones of turbulences sometimes I wonder if I tightened the screws because everything is "dancing" under my feet.
In the past with the soft mast/fuse (TMast) from Takuma (still more than the one of Armstrong) it was exactly the same and still more often. Even in the tacks at the start when you go upwind the mast was doing like a spin out especially with a big front wing. With a smaller one never during the tack; only in straight line for a certain speed.
Similar experience with me, I'm looking forward to the performance mast upgrade!
Select to expand quoteSonsaleta said..patronus said..
Sometimes I feel like there is an instability with a frequency of several Hz. I think may be a yaw wobble in the Armstrong mast. It seems stiff in other dimensions but out of water if you give it some yaw and let go it vibrates for ages at several Hz.
It seems to set in occasionally on a run, not all the time, and indeed I can repeat a run in the same stretch of water at same speed and it isn't there. it is almost as if it gets into a resonance. Anyone else experience this, and identified what starts it off and how to stop it
Happens to me all the time when I reach a certain speed even with the 725 or 525. I love wings and fuse from armstrong but I think the mast is a bit too soft.(I use 72cm) Happens to me often before to catch a wave when I accelerate when I cumulate speed from the wing + speed from the swell. Happens just before to go in free fly to start to surf.
Also in the zones of turbulences sometimes I wonder if I tightened the screws because everything is "dancing" under my feet.
In the past with the soft mast/fuse (TMast) from Takuma (still more than the one of Armstrong) it was exactly the same and still more often. Even in the tacks at the start when you go upwind the mast was doing like a spin out especially with a big front wing. With a smaller one never during the tack; only in straight line for a certain speed.
The "dancing under your feet" seems to be a characteristic of the HA wings in turbulence. I find I mostly ignore it now and crack on. A mid aspect won't feel the turbulence nearly as much. It would be cool to test the performance mast with the HA foils back to back with the standard mast in turbulent conditions to see how much of this is mast related vs HA behaviour.
I get the wobble on some runs but not others in same conditions with 1550 V2 and wonder if it is something to do with stance otherwise it would always happen?
The mast is a big factor. Some brands of ha wings aren't very stiff. Then of course on top of that ha wings are to be more demanding of the mast and rider when messy water is at play mostly just because of
Armstrong, axis, unifoil, cabrinha and lift are all either fixing or will fix their masts. Maybe even takuma.
Select to expand quoteWindoc said..Sonsaleta said..patronus said..
Sometimes I feel like there is an instability with a frequency of several Hz. I think may be a yaw wobble in the Armstrong mast. It seems stiff in other dimensions but out of water if you give it some yaw and let go it vibrates for ages at several Hz.
It seems to set in occasionally on a run, not all the time, and indeed I can repeat a run in the same stretch of water at same speed and it isn't there. it is almost as if it gets into a resonance. Anyone else experience this, and identified what starts it off and how to stop it
Happens to me all the time when I reach a certain speed even with the 725 or 525. I love wings and fuse from armstrong but I think the mast is a bit too soft.(I use 72cm) Happens to me often before to catch a wave when I accelerate when I cumulate speed from the wing + speed from the swell. Happens just before to go in free fly to start to surf.
Also in the zones of turbulences sometimes I wonder if I tightened the screws because everything is "dancing" under my feet.
In the past with the soft mast/fuse (TMast) from Takuma (still more than the one of Armstrong) it was exactly the same and still more often. Even in the tacks at the start when you go upwind the mast was doing like a spin out especially with a big front wing. With a smaller one never during the tack; only in straight line for a certain speed.
The "dancing under your feet" seems to be a characteristic of the HA wings in turbulence. I find I mostly ignore it now and crack on. A mid aspect won't feel the turbulence nearly as much. It would be cool to test the performance mast with the HA foils back to back with the standard mast in turbulent conditions to see how much of this is mast related vs HA behaviour.
I've experienced the same thing with the HS wings and it's not just happening in white water. That said it's not very frequent AND my mast is a V1 not A+. In my case this could be a factor. Even if there wasn't this occasional "wobble" I would still be curious about how the new design impacts performance. More speed and stability can't be a bad thing.
Supposedly there have been some running changes on the masts, and the latest ones are stiffer. Rumors tho.
I have a relative new 85A+ mast and have the same wobble with the CF300 stabiliser now and then, not with the HS232!, which is fine. When I hit my foil on land, it vibrates at a certain frequency.
There is a discussion on Axis Facebook group about sudden loss of list and the Axis designer says "It is the mast not being stiff enough for your weight and power, when you load hard especially upwind you can get a release on the mast due to twisting buckling. Some riders experience it more than others, not sure why" and someone says "Armstrong guys are launching a new mast they say is designed to avoid a type of ventilation you get along the mast where air bubbles travel towards the foil and release, disturbing the flow on the stab, perhaps that's the issue happening here?" Rreads like a flex in the mast can lead ventilation and air getting to stab.
I wonder if what's happening is that depending on how much you twist your hips you might have equal downward weight through both feet over the lift from the foil, but unequal transfer of the sideways force from the wing. If the sideways force from the wing goes more though your front than back foot then there is more of a turning moment trying to point the nose downwind. This force is counteracted by the flow of water over the mast trying to get the mast, and hence board, to point in the forward direction. The greater the sideways force from the front foot the greater the angle of attack of the mast has to be to counteract it, and the greater the negative pressure on the other side of the mast sucking air. So, sailors who put more the sideways force through the front foot get more ventilation.
Select to expand quotepatronus said..
There is a discussion on Axis Facebook group about sudden loss of list and the Axis designer says "It is the mast not being stiff enough for your weight and power, when you load hard especially upwind you can get a release on the mast due to twisting buckling. Some riders experience it more than others, not sure why" and someone says "Armstrong guys are launching a new mast they say is designed to avoid a type of ventilation you get along the mast where air bubbles travel towards the foil and release, disturbing the flow on the stab, perhaps that's the issue happening here?" Rreads like a flex in the mast can lead ventilation and air getting to stab.
I wonder if what's happening is that depending on how much you twist your hips you might have equal downward weight through both feet over the lift from the foil, but unequal transfer of the sideways force from the wing. If the sideways force from the wing goes more though your front than back foot then there is more of a turning moment trying to point the nose downwind. This force is counteracted by the flow of water over the mast trying to get the mast, and hence board, to point in the forward direction. The greater the sideways force from the front foot the greater the angle of attack of the mast has to be to counteract it, and the greater the negative pressure on the other side of the mast sucking air. So, sailors who put more the sideways force through the front foot get more ventilation.
The exact issue you described with the mast and how the new performance mast addesses it, is shown in this video in the first minute.
Thanks, first time I've seen ventilation mentioned by Armstrong, and am interested in what design changes that makes it less susceptible to ventilation. I occasionally get ventilation and board collapses back onto sea, but wobble feels different so maybe two things going on.
I guess with ventilation once it starts it won't stop but the wobble goes on 10-20 secs, and that judgement comes from windsurfing where chop can lead to ventilation and once that starts you have to slow down to off the plane for the board to reattach to water.
Seen one mast supplier (Cedrus?) describe an optional bit of plastic to wrap around the mast to disrupt flow of air and other say if a serious problem get a rubber band.
I emailed Armstrong and they kindly checked a video of me assembling and noticed a 1mm gap between front wing and fuse, and advised connecting with sharper blows which I've done and no gap. Also suggested standing feet offset and body in line with mast.
I've got the original mast only and that's a noodle compared to the A plus. And the new mast which I've seen in the flesh makes the A plus seem like a noodle as well.
That being said I never experience the wobble some of you are mentioning except on the HA wings and that's through turbulent water. Then again maybe I'm just used to it and don't notice it?
From what I got from talking to armie, there's a whole lot more to developing a mast apart from it being "stiffer". He still wants it to be reactive and not "dead" feeling. Plus the mast ventilation thingy mentioned above which went well over my head.
but. they aren't going to be cheap 
I'm 80kg and have never found the A+ 85 or even the original 72 mast too flexy , I have ridden other brands that definitely feel wobbly and I didn't like that and understand the difference . I do understand the reactive flex though ,and it's a fantastic feeling being able to load up energy or tension in a cut back and then release all that energy into a roundhouse turn and then back into another cutback over and over. The extra "spring" and acceleration is super addictive and I don't know that I would want to give that up.
Yeh I use an 85 mast. Have been on my sons 72 a number of times and yeh that is stiff as. But the original 85 is a bit floppy jalopy.
