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Hydrofoil stiffness & fuselage connections

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Foil
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Re: Hydrofoil stiffness & fuselage connections

Postby Foil » Tue Oct 15, 2019 9:30 am

Surely a little flex in Moses carbon masts for freeride is a good thing?
it acts like a damping device, to cancel out the little bit of turbulence that happens around the rig under the surface,
as long as its not too flexible for the use its being subjected to.
Racers and speed freaks will want masts that have less damping, more stiffness, less energy absorbing factors like softness,
and moses do account and adjust their masts just for this, the entry level 91 cm mast is very soft compared to the 111 mast or even the 101 mast, the carbon lay up from the 91cm mast to the 101 mast is a jump from 20 layers to 25 layers, and the extra stiffness can be felt quite easily when you twist the mast with the fuse connected, or secure the mast and rock it back and forth, the difference is there to be seen or measured if you are that keen to pin down the numbers like I did last year,
the 91 cm moses carbon mast is silly soft compared to the 101, and how it compares to the other moses race masts must be jaw dropping.
but are these super stiff masts above the 101 desirable for the average joe, foil freeriders?
or are they just not great fun to use, smooth V jittery maybe?
I don't know
but there has to be a point where super stiff is not great to use, no? yes?
what I do know is I want to change my shallow water 84cm Aluminium slingshot mast for a carbon mast, its too heavy by far.
once you own carbon you are so aware of how nice and light translates to feeling good about your lightweight rig,
heavy kit is a bummer for most.

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Re: Hydrofoil stiffness & fuselage connections

Postby Kamikuza » Tue Oct 15, 2019 1:03 pm

Foil wrote:
Tue Oct 15, 2019 9:30 am
Surely a little flex in Moses carbon masts for freeride is a good thing?
it acts like a damping device, to cancel out the little bit of turbulence that happens around the rig under the surface,
as long as its not too flexible for the use its being subjected to.
Racers and speed freaks will want masts that have less damping, more stiffness, less energy absorbing factors like softness,
and moses do account and adjust their masts just for this, the entry level 91 cm mast is very soft compared to the 111 mast or even the 101 mast, the carbon lay up from the 91cm mast to the 101 mast is a jump from 20 layers to 25 layers, and the extra stiffness can be felt quite easily when you twist the mast with the fuse connected, or secure the mast and rock it back and forth, the difference is there to be seen or measured if you are that keen to pin down the numbers like I did last year,
the 91 cm moses carbon mast is silly soft compared to the 101, and how it compares to the other moses race masts must be jaw dropping.
but are these super stiff masts above the 101 desirable for the average joe, foil freeriders?
or are they just not great fun to use, smooth V jittery maybe?
I don't know
but there has to be a point where super stiff is not great to use, no? yes?
what I do know is I want to change my shallow water 84cm Aluminium slingshot mast for a carbon mast, its too heavy by far.
once you own carbon you are so aware of how nice and light translates to feeling good about your lightweight rig,
heavy kit is a bummer for most.
I want as little flex in the whole system too. When I tell my gear to do something, I don't want it bobbling and wobbling around, or needing to be waited for or compensated for, and I don't want it moving around under me in response to the water or transmitting wobbles.

The extra 15cm between my two masts is noticeable and I don't like the difference in response time and flex.

Talking to the windsurfer foil riders, they apparently do want some flex for the way their gear works :shrug:

Regarding weight -- you want a carbon mast as stiff as a stiff aluminum one, you're going to have almost the same weight ... although your wallet will be a lot lighter!

...maybe it'd be different for a lighter rider...?

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Re: Hydrofoil stiffness & fuselage connections

Postby dave1986 » Tue Oct 15, 2019 2:16 pm

This thread topic has made me ask some interesting questions....

If carbon masts are generally less stiff but lighter than aluminium masts. Or for the same stiffness carbon masts end up being similar weight as aluminium masts.... then why would any of the professional racers ever use a carbon mast? Or is it that the benefits or carbon are real, but marginal?

For the sake of a few extra layers of relatively inexpensive carbon, why dont companies such as Moses just up the stiffness and weight of their masts?

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Re: Hydrofoil stiffness & fuselage connections

Postby BWD » Tue Oct 15, 2019 2:23 pm

For the same weight/stiffness the carbon can be thinner for less drag, and the hydrodynamic profile can vary from root to tip. Usually near the top, it is thicker for strength and stiffness, farther down it is shaped to avoid ventilation, closer to the bottom optimized for lowest drag.
Aluminum on the other hand, is a uniform extrusion, for which more stiffness means higher section and more drag, or much thicker walls and high weight. Thicker is ok if you aren’t looking for speed, but weight is not so popular.
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Re: Hydrofoil stiffness & fuselage connections

Postby dave1986 » Tue Oct 15, 2019 5:20 pm

BWD wrote:
Tue Oct 15, 2019 2:23 pm
For the same weight/stiffness the carbon can be thinner for less drag, and the hydrodynamic profile can vary from root to tip. Usually near the top, it is thicker for strength and stiffness, farther down it is shaped to avoid ventilation, closer to the bottom optimized for lowest drag.
Aluminum on the other hand, is a uniform extrusion, for which more stiffness means higher section and more drag, or much thicker walls and high weight. Thicker is ok if you aren’t looking for speed, but weight is not so popular.
So it sounds like carbon is superior to aluminium for stiffness and weight (but not price) when comparing masts of similar thickness and length. However, if the manufacturer decides to make the carbon mast on the ligher side (as appears to be the case with Moses) then you end up with a light weight but flexible mast.

I suppose it's a balance of these variables: PRICE vs WEIGHT vs STIFFNESS vs HYDRODYNAMICS and everyone's priorities will be different depending on their sport/style of riding, bodyweight, and the size of their wallets!

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Re: Hydrofoil stiffness & fuselage connections

Postby tomtom » Tue Oct 15, 2019 7:04 pm

There is carbon and CARBON,

Normal stuff and UHM stuff - UHM is not some better is 2x better which almost translate to 2x stiffer mast. UHM is almost racing only and about 3x more expensive in final product
BUT and this is very BIG BUT. Nobody really know that stiffer is really that much better. If you dont ride same mast /not different lenght, - cause off course shorter mast is snapier /I don't like the difference in response time and flex/ and also same profile - in same condition cause turbulence in water causing wobbly feel that can be feel as wobbly setup.
Then competent rider can make some conclusions about flex. And this also mean flex where how much and very important how damped. With skis and snowboards it takes decades to get it right.
Right now considering how very flexible some mast are i dont think for freeride is that much important. Why? Because if it was that much important everybody will immediately feel difference and will be death obvious that mast must be super rigid. Whole situation when some prefer that other that and nobody really know /look at french foil making forums/ indicate that it isnt as important /to some reasonable extent/. Fuselage is different matter and everybody WILL feel soft fuselage - it will vibrate and causing heavy drag.

Reasonable cheap mast for freeride big wings should be from normal carbon - and can be quite thick /drag isnt as important because big wing dominate drag wise and operating speeds will be much lower/ Mast thickness is single most important parameter for stiffness and strength. Stiffness is related to thickness with CUBE so 2x thick mast is 8x stiffer. So every mm will help tremendously.

This is for freeride big wing only - off course racing while 60kmh is different universe and everything must be as stiff as possible etc...

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Re: Hydrofoil stiffness & fuselage connections

Postby stevez » Tue Oct 15, 2019 9:05 pm

tomtom wrote:
Tue Oct 15, 2019 7:04 pm
Right now considering how very flexible some mast are i dont think for freeride is that much important. Why? Because if it was that much important everybody will immediately feel difference and will be death obvious that mast must be super rigid. Whole situation when some prefer that other that and nobody really know /look at french foil making forums/ indicate that it isnt as important /to some reasonable extent/. Fuselage is different matter and everybody WILL feel soft fuselage - it will vibrate and causing heavy drag.
Most people only know what they ride.
Try a stiff setup back to back with a noodly one and feel the difference for yourself. Of course you got to do stuff to feel the difference make some carving turns etc.
The only flex you get from a mast is lateral, and maybe some torsional. I can't see how any of that is beneficial for dampening or any other purpose.
Skis and snowboards is not the correct analogy.
Full suspension mountain bike frames are. There's no amount of flex on any axis that is desirable, it's pure stiffness vs weight at a given cost. You only want movement in the suspension, nowhere else.
For foils the trade-off is a little different, it's stiffness vs hydrodynamic efficiency at an acceptable weight for a given cost.
I do agree that many freeride surf foils are not correctly optimised in this respect, especially when using big wings.

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Re: Hydrofoil stiffness & fuselage connections

Postby airsail » Tue Oct 15, 2019 10:27 pm

The new Slingshot carbon mast will be interesting but I’ve only seen snippets of info. Supposed to be full HM carbon, double moulded and possibly hollow.

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Re: Hydrofoil stiffness & fuselage connections

Postby tomtom » Tue Oct 15, 2019 11:52 pm

You mostly get me all wrong. Im no proponent of flexible mast - i just think /presume/ its not that much of problem - Saying hello to all Onda riders.

About this "Try a stiff setup back to back with a noodly one and feel the difference for yourself." Who is here who ride exact same setup with noodly mast and stiff mast?
Cause till moses start making alu mast i did not know about single one foil setup where you can choose between noodly and stiff mast /same lenght/.
About damping - i wasnt talking about suspension damping at all - i was talking about mast flex rebound rate /resonant frequency and Q of this resonance/. This will be totaly different for similar flexing alu and sandwiched carbon /moses 91/

Again i think the stiffer the better. But nothing is completely solid and we still dont know how much flex is benign. /and character of this flex/ If we know then mast can be further optimized either hydrodynamically or for weight.

BTW from Armstrong webpage
The unique quad c beam core layup delivers a mast with smooth consistent reactive flex, generating sweet handling response and better stability by smoothing out bumps and flexing precisely to drive you through turns

they are probably most /over/engineered foils on market right now. They put extreme amount of work to make fuselage /Titan core in carbon/ and its connection as stiff as possible and yet they claim that they mast is flexible. I dont know if its marketing BS but at least is worth of thinking about.

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Re: Hydrofoil stiffness & fuselage connections

Postby Kamikuza » Wed Oct 16, 2019 5:44 am

Wouldn’t riding short and long version of the same mast be the same experience you’re looking for?

This year’s Axis gear will let you use all the masts with the same fuselage.


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