Author Topic: wobble feeling  (Read 1750 times)

liv2surf

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wobble feeling
« on: April 17, 2020, 10:21:17 PM »
I am a very new SUP foiler who has been SUP surfing for 4y and kite foiling for ~5y. When standing on the board in surf I have noticed a weird foil sensation that I wanted help Ďinterpretingí. When I am standing on my 6í6Ē 125-135L SUP foil board with foil tracks  with a big 1720 cm^2 foil on a thin 28Ē aluminum mast, I feel a wobbling or vibration/oscillation of the foil underneath me. I am guessing this is a well known phenomenon.  It is a bit disconcerting. Is this most likely the foil boxes and the bottom skin flexing or the mast itself bending? (I did search for this subject but did not find results that answered my question). If this is the boxes and bottom skin flexing, is this board likely to blew out the foil boxes?
9'6" CRUZ Surf SUP (152L)
6'6" CRUZ 'CIM' Foil SUP (130L)
9'5" Naish Mana (165L; broken)
8'8" F'One Madeiro Pro (145L; sold)
Chinook Thrust 92 fixed-length paddle
Half Moon Bay, CA

jondrums

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Re: wobble feeling
« Reply #1 on: April 18, 2020, 12:09:15 AM »
likely the mast flexing.  Big wing and not very stiff mast is very noticeable in exactly this way when standing on the board

Phils

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Re: wobble feeling
« Reply #2 on: April 18, 2020, 03:26:29 AM »
You can probably figure this out on land by pushing on foil and seeing where the movement is. 

Dwight (DW)

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Re: wobble feeling
« Reply #3 on: April 18, 2020, 04:39:40 AM »
Itís the mast flexing. Itís why all our local crew ride Axis. It is the stiffest mast on the market. Once you ride a stiff mast, you immediately figure this out, by going back to your old setup for a comparison. Iíve felt mast wobble so bad, the vibration came through the deck into my feet.

Also be sure to shim and hammer your base plate onto the mast. This continues to be a design weakness in all brands, including Axis. Itís a product of the aluminum extrusion, where the extrusion dies wear with age, causing the masts to change thickness. So itís never going to go away as an issue, until someone smart, designs a better mast to base plate system.


Itís a crying shame so many brands continue to offer masts too flexible for SUP surfers.
« Last Edit: April 18, 2020, 04:43:32 AM by Dwight (DW) »

liv2surf

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Re: wobble feeling
« Reply #4 on: April 18, 2020, 11:22:32 AM »
Thanks for the replies. Yes, I had seen the thread where people were discussing that Axis is a SUP favorite due to stiffness. It is interesting that my aluminium mast (Cloud IX) would flex/wobble more than the boxes and board bottom.  I guess if boxes flex you get cracks followed by failure so this is probably correct.  I agree that I should be able to convince myself of which mode of wobble is occurring by applying force to front wing with foil up (out of water) and watching where I see motion.


See my post about new video about new Armstrong Wing Foil SUPS and their use of 2 carbon parabolic stringers encasing the foil boxes:
https://www.standupzone.com/forum/index.php/topic,35269.msg414219.html#msg414219
« Last Edit: April 18, 2020, 11:31:53 AM by liv2surf »
9'6" CRUZ Surf SUP (152L)
6'6" CRUZ 'CIM' Foil SUP (130L)
9'5" Naish Mana (165L; broken)
8'8" F'One Madeiro Pro (145L; sold)
Chinook Thrust 92 fixed-length paddle
Half Moon Bay, CA

liv2surf

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Re: wobble feeling
« Reply #5 on: April 19, 2020, 10:54:20 PM »
I did not like the wobble of the Cloud IX 28" aluminium mast on my SUP.

I am planning to buy a new foil for SUP and wing SUP. I am deciding between Armstrong with 72cm carbon mast and Axis with 68 or 75 cm aluminium or 76 cm carbon mast.

Will the Armstrong and Axis carbon masts have too much wobble (like the Cloud IX)? Will the thicker Axis mast (19mm, I believe) be the only one with sufficient stiffness for SUP?

You comments are appreciated.
« Last Edit: April 19, 2020, 10:57:14 PM by liv2surf »
9'6" CRUZ Surf SUP (152L)
6'6" CRUZ 'CIM' Foil SUP (130L)
9'5" Naish Mana (165L; broken)
8'8" F'One Madeiro Pro (145L; sold)
Chinook Thrust 92 fixed-length paddle
Half Moon Bay, CA

Dwight (DW)

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Re: wobble feeling
« Reply #6 on: April 20, 2020, 04:20:33 AM »
Will the Armstrong and Axis carbon masts have too much wobble (like the Cloud IX)? Will the thicker Axis mast (19mm, I believe) be the only one with sufficient stiffness for SUP?

My buddy rode the Axis carbon. He said forget about it. Too much flex and twist. Heís staying on aluminum.

Army Armstrong says mast flex is a design feature. So forget about it.


ninja tuna

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Re: wobble feeling
« Reply #7 on: April 20, 2020, 05:11:22 AM »
On my armstrong in the surf and in the choppy conditions I have never noticed this wobble feeling you are dealing with.  I have 72cm armstrong mast.

Dwight (DW)

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Re: wobble feeling
« Reply #8 on: April 20, 2020, 08:02:15 AM »
Some masts, while not feeling a direct wobble, do make a SUP feel less stable. You really have to ride a super stiff mast long enough to know it well, then try something less stiff, and itís a big time hell no.

Phils

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Re: wobble feeling
« Reply #9 on: April 20, 2020, 11:00:45 AM »
My guess is stiffest carbon mast out there is LP in Hood River.  It has zero flex but on heavier side.  Peter will make one any length you want.  He also has a wide selection of high aspect foils. 

I heard an interview of the guy who started Axis and was impressed to with commitment to making a stiff mast.(the bigger Al one).

Haven't read a lot of complaints about Armstrong.  Armie claims the location of flex matters and that his masts are tapered and flex at the bottom and not the top.

flkiter

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Re: wobble feeling
« Reply #10 on: April 20, 2020, 11:28:02 AM »
Less flex also lets you paddle is harsher conditions. I was tapping out in about 12 knot winds with the Neil Pryde, now I can stay paddling in over 20 knots with the Axis. My local kiters liked it better when I couldn't keep on the waves in the higher winds.

jondrums

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Re: wobble feeling
« Reply #11 on: April 20, 2020, 01:01:49 PM »
totally agreed with DW - hell no on mast flex.  It has always puzzled me that armstrong touts it as a feature.   The difference going from the old gofoil mast to the new wider/stiffer one is like night and day and I would never go back.  I say the stiffer the better.

liv2surf

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Re: wobble feeling
« Reply #12 on: April 20, 2020, 01:09:37 PM »
Thanks for everyone's comments here. Obviously, there is a bit of difference of opinion here, though the consensus is stiffer is better for SUP. NI agree Army thinks flex is a design element and flex at bottom is more acceptable... but I suspect he is coming more from a kite and/or prone foil background (where you don't need the stiffness for stability to stay out there as needed on SUP).

One point of clarification. Axis has two mast thicknesses, the 16mm and the 19mm. Are comments about stiff Axis mast specific to the 19mm masts?

So, advocates of stiff masts for SUP foiling believe that the benefits of stiffness out weighs the disadvantages of weight?
9'6" CRUZ Surf SUP (152L)
6'6" CRUZ 'CIM' Foil SUP (130L)
9'5" Naish Mana (165L; broken)
8'8" F'One Madeiro Pro (145L; sold)
Chinook Thrust 92 fixed-length paddle
Half Moon Bay, CA

ninja tuna

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Re: wobble feeling
« Reply #13 on: April 20, 2020, 01:24:37 PM »
I have ridden these foils enough to know I do not feel them flex or vibrate .  I have especially dug them hard in terms of turns and stresses behind the boat at higher speeds.  I have had out in the surf in up to head high,  and did not feel any wobble or vibration.  And his masts are wood core with the carbon fiber so they are not going to act like the pure carbon masts out there. One of the reasons I went with the armstrong foils.

Dwight (DW)

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Re: wobble feeling
« Reply #14 on: April 20, 2020, 01:54:56 PM »
19mm mast. 5oz lighter in carbon and less stiff. When carbon matches that 19mm aluminum mast, itĎs heavier. Axis did the thicker at the top carbon trick too.

CloudIX released a carbon mast and it was heavy. They told me at surf Epoxy they just made one because some people wanted one, regardless....

Lots of people keep trying.

Iím curious about Slinghotís new trick carbon mast coming. Dealer materials were send out months ago. Still havenít seen the public release. They claim to have the stiffest carbon mast ever made. Going by memory, so donít quote me.