Forums > Stand Up Paddle Foiling

Mast Mod for extra stiffness

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Created by Fishdude > 9 months ago, 28 Apr 2019
Fishdude
300 posts
28 Apr 2019 7:24AM
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Actually a base plate mod that better supports the mast.
I was hoping for a 50% reduction in flex.
It ended up stiffer than I expected.

1\8" x 2" aluminum 6063 from Lowe's. A little Tig welding (by a friend), and some JB weld to fill in the gaps. Some file and sanding work...







Piros
QLD, 6995 posts
28 Apr 2019 11:13AM
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Wow that's pretty full on. Good idea though. That mast looks really long , did you think about just shortening it a bit and maybe putting some tack welds on the shoulder of the base plate. It would have had a similar result.

Thats a lot of drag to deal with paddling for waves and it would really grab hard on touch downs . I would have just cut my losses and got another foil that doesn't flex so badly. Keep us posted on results.

Fishdude
300 posts
28 Apr 2019 10:46AM
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Select to expand quote
Piros said..
Wow that's pretty full on. Good idea though. That mast looks really long , did you think about just shortening it a bit and maybe putting some tack welds on the shoulder of the base plate. It would have had a similar result.

Thats a lot of drag to deal with paddling for waves and it would really grab hard on touch downs . I would have just cut my losses and got another foil that doesn't flex so badly. Keep us posted on results.



Originally I thought of it like training wheels. Less flex easier to lean on... Especially behind a boat.

The photo is with the 80cm mast I have shorter masts and smaller wings... I notice flex with the 100cm wing on the 80cm mast, it's not bad, I think it's normal. BUT if I have the option to have next to zero flex with little down side... I figure why not give it a try.

So far I don't notice any extra drag. But I'm sure there is some. The extra surface area is in about the same as a fin so I don't think that's a problem. But the close proximity to the mast has to create some extra trublance, so that's the concern I have as far as extra drag.

If I was to do it again I'd just use the same one plate mount. The second uncut stock plate wasn't needed. I didn't expect it to be as strong as it is. And I'd make it a little shorter like 6" tall instead of all most 8. Then the extra surface area and weight would be next to nothing.

The only down side I have so far is taking it apart I can't wiggle it apart. I have to use a long screw to thread into the mast, the tap it apart.

Seajuice
NSW, 907 posts
28 Apr 2019 1:12PM
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Nice job. I was thinking of something similar the other day when hearing about mast wobble. I don't think you will have any problems using it. Not major anyway. A bit surprised the main brands haven't done this already. The only down side to this could be a hard side on hit by a big wave that may damage the board instead of bending or breaking the mast.
Why bother pulling it apart? Or is there a corrosion issue with a carbon mast?

Fishdude
300 posts
9 May 2019 1:24AM
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Thanks Seajuice. I think it could be done without adding any weight also. It was a fun experiment.

So I tested a few things.

Subjectively, I like the extra stability both paddling and flying, seems a little more reactive (less lag feeling) everything just seems a little easier for a tall heavy newb like me.

Objectively.
Flex test, Reduction in flex.
25-28% with a 65cm mast.
20-30% with a 80cm mast.

Weight added 195 grams.

Tested resistance to flow by holding it in water at 50 Kph couldn't hardly tell it was even in the water.

Flex Test was done with 5kg 10kg and 15kg weights on a 90 and 110 degree side load. Stock plate vs my Stiffy.






tomooh
276 posts
9 May 2019 2:11AM
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Good work. I was wondering if filling a hollow mast with glass and resin would help with flex and to stop bending. It would add weight but not drag

Fishdude
300 posts
9 May 2019 3:12AM
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tomooh said..
Good work. I was wondering if filling a hollow mast with glass and resin would help with flex and to stop bending. It would add weight but not drag


Yeah I was wondering if people have tried other things like that also.

balinnz
17 posts
9 May 2019 4:09AM
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Youll always get the most strength by adding material to the outside not the inside, hence why the masts are hollow, Axis has such a stiff mast purely because their chord thickness is way biggger than anyone elses and there is physical material further away from the centre.

drsurf
NSW, 179 posts
10 May 2019 11:24PM
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Have to agree with balinnz. According to the main man behind the Axis foil gear: "Adrian Roper determined that the current range of available masts on the market were simply not stiff enough beyond 70cm length, so he designed a mast that is 216% stiffer and that will provide the most direct feeling connection between the rider, their board and the amazing Axis Hydrofoils."

A lot less drag with an inexpensive Axis mast than with the bracing shown here. Stiff all the way to the foil too

Fishdude
300 posts
11 May 2019 7:31PM
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drsurf said..
Have to agree with balinnz. According to the main man behind the Axis foil gear: "Adrian Roper determined that the current range of available masts on the market were simply not stiff enough beyond 70cm length, so he designed a mast that is 216% stiffer and that will provide the most direct feeling connection between the rider, their board and the amazing Axis Hydrofoils."

A lot less drag with an inexpensive Axis mast than with the bracing shown here. Stiff all the way to the foil too


This DIY project has zero detectable drag, cost $13 and about 3 hours of time. Inexpensive is relative.

I agree with balinnz also. More physical material further away from the centre the better. I know of a few manufacturers now making thicker stiffer mast and I'm glad there doing it. One manufacture that I like intentionaly makes their mast with tapered stiffines. Stiffer at the board and more flex at the wing.

I'm curious as how Axis measured stiffness to get 216% stiffer?
I measured Orginal flex under load as base, (0% improvement), and "no flex at all" as being 100% improvement. So, over 100% was not possible the way it measured.

Edit. Neveemind I got it, They added thickness and material to be 216% stiffer than their previous model. Stiffer vs less flex are two different things so they can't be compared.

MickChard
VIC, 183 posts
12 May 2019 8:54PM
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So can some on shine in on mask flex is it really no good & why ??

My new carbon mash has some flex like a fair bit more that the NP but it doesn't feel better or worse when up and riding ... I don't think any way unless I'm missing something ..

I see most companies are moving to carbon masks as well

DWF
618 posts
12 May 2019 9:03PM
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MickChard said..
So can some on shine in on mask flex is it really no good & why ??

My new carbon mash has some flex like a fair bit more that the NP but it doesn't feel better or worse when up and riding ... I don't think any way unless I'm missing something ..

I see most companies are moving to carbon masks as well


The easiest way to feel the benefits of a stiff mast, is to paddle one on a SUP. It immediately makes the SUP feel more stable paddling. This affect is amplified with huge wings. A flexible mast paired with a huge wing can make a SUP wobble so bad you can feel vibrations in the deck of the board.

The difference while flying might take some more back to back testing to pickup on the benefit. But its there.



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"Mast Mod for extra stiffness" started by Fishdude