Author Topic: Foil Box Failure  (Read 3121 times)

Beasho

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Foil Box Failure
« on: December 03, 2017, 03:32:08 PM »
Things were great until they weren't. 

The last 2 days I was solo out at Mavericks in the morning attempting some drops.  Eventually moved inside and caught some screamers in the 10 - 15 ft range.  I went down paddling for a wave and was sitting in a safe zone when a wave rose up I was thinking "I am safe waves don't break here. . . . I am in a safe spot . . . wave stands up . . Hey I am in a safe spot!"  BOOM!  A 10 - 12 foot lip came down on me with my board slightly behind. 

Separation . . despair . . thankful the foil DOES actually float.  Retrieval, then perplexity at how to paddle back in with this thing. . . . .   

Long story short I think a combination of epoxy and maybe JUST gorilla glue to set back into place.  The Divinycell box sheared in half.  The carbon Tuttle is 100% intact.  All I need is to re-adhere with something STRONGER than Divinycell. 

The last 2 photos show the box and how it is sitting back in place.  It's pretty snug.  I'll just need to rebuild a bit of Styrofoam which is actually pretty easy when combined with Gorilla Glue.   
« Last Edit: December 03, 2017, 03:53:23 PM by Beasho »

Beasho

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Re: Foil Box Failure
« Reply #1 on: December 03, 2017, 03:34:43 PM »
As my Tesla Engineer neighbors observed "Something has to break.  Probably better this happens and you just put it back in than the whole board breaking apart or your foil snapping in half."

Good point.  Maybe this is just par for the course in bigger waves.  Another reason to aspire to the Gorilla glue re-installation.  Quick and relatively painless.

Then I can put the effort into a solid upper and lower re-lamination with some Carbon patches.   

Beasho

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Re: Foil Box Failure
« Reply #2 on: December 03, 2017, 03:35:11 PM »
What it looked like from the Surf cam when I was foil testing solo at Mavericks.
« Last Edit: December 03, 2017, 03:36:42 PM by Beasho »

jrandy

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Re: Foil Box Failure
« Reply #3 on: December 03, 2017, 08:46:41 PM »
Wow. I'd be thinking about some sort of hd foam collar with an inside dimension to match existing to help hold it together and spread the load more evenly to the skin.
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surfcowboy

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Re: Foil Box Failure
« Reply #4 on: December 03, 2017, 09:05:50 PM »
Beasho, glad you're ok man. Stuff can be fixed.

I'm surprised that those boxes don't have a flange built onto them. Seems like a top flange would be a great idea on those Tuttles.


PonoBill

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Re: Foil Box Failure
« Reply #5 on: December 04, 2017, 09:53:28 AM »
That's why I put a big carbon patch on my foil board, top and bottom. To spread the load. I look at those long masts and big wings and see an impossible construction problem. No matter what you do there will be a failure point, but I'd like to move that up the force curve as far as feasible. Foam alone isn't going to cut it.

I think the entire Tuttle box notion is pretty silly. A perfect example of using something inappropriate because it was used somewhere else for a good reason. Windsurf foils use a Tuttle box--because it's already there! Windsurf boards use a Tuttle box for their fins because of all the force applied to their fins by the sail. The heavy sandwich construction and engineered support of a windsurfer Tuttle makes it OK for a foil--though it's probably not ideal there either. So surf foilboards, with their much flimsier construction than any windsurfer, follow along in the practice. That's just goofy. There is nothing about a Tuttle box--deep or otherwise--that makes it suitable for attaching a foil. The surprising thing is that it works at all. 

If you were going to design a foilboard from first principles you would likely wind up with some sort of through-bolted plate to spread load top and bottom, with an hourglass tapered chunk of PVC to evenly distribute the load to the board surfaces, probably reinforced with tapered patches to reduce the stress risers created by the patch edges. At the very least a Tuttle cartridge with collars top and bottom like jRandy suggests--a neat solution.

A set of mast tracks installed in the bottom with best practices for distributing the load to just the bottom surface (PVC cartridge, glassed under) would be an adequate alternative. Last on my list would be a Tuttle box in a PVC cartridge, with reinforcement top and bottom to spread the load across the surfaces. I wouldn't consider a Tuttle in a cartridge installed without surface reinforcement. What's holding it in place? The edges of the surface and some EPS foam you can crush with your fingers?

Looking at the way your box failed I see no surprises.
« Last Edit: December 04, 2017, 10:06:30 AM by PonoBill »
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supuk

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Re: Foil Box Failure
« Reply #6 on: December 04, 2017, 10:54:11 AM »
What about a double thick insert like I do then grind of the old foam of the box and route a Chanel in the center so you have the ability to run booth styles of mount?

eDUBz

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Re: Foil Box Failure
« Reply #7 on: December 05, 2017, 10:05:47 PM »
Spread the load - like a pyramid have a nice solid wide base. Get rid of the tuttle box and add mast tracks. Tuttle Boxes are good if you install it on a board with a lot of concave. This L41 was just glass/epoxy and had a lot of flex. I did a nice glass blend to mitigate the flexing.













« Last Edit: December 05, 2017, 10:08:39 PM by eDUBz »
@rf.boardworks

eDUBz

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Re: Foil Box Failure
« Reply #8 on: December 05, 2017, 10:16:49 PM »
Here’s one of my tuttle box Reinforced install after a wreck. The
Layup held up, the box inside shattered and he bent his mast.


@rf.boardworks

Beasho

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Re: Foil Box Failure
« Reply #9 on: December 19, 2017, 04:20:33 AM »
No way to keep up with eDUBz repair jobs.

What I was hoping was that Gorilla Glue would serve as a quick and effective means to repair fin box installations serving as a foundation for the fin box in the foam. 

In my example the Divinycell cassette holding the Tuttle box sheared.  I did some test glueing Divinycell with Gorilla Glue and the results suggested the Gorilla Glue bond is stronger than the original Divinycell PVC foam structure. 




jrandy

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Re: Foil Box Failure
« Reply #10 on: December 19, 2017, 08:36:54 AM »
Thanks for the video Beasho. It's good to know that Gorilla Glue is not the weak link.
I love it really enjoy when people beat surfboard materials with hammers on the interweb.
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blueplanetsurf

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Re: Foil Box Failure
« Reply #11 on: December 20, 2017, 09:05:54 AM »
Here’s one of my tuttle box Reinforced install after a wreck. The
Layup held up, the box inside shattered and he bent his mast.




Is the cracked Tuttle box a molded carbon box or one of the molded plastic boxes? 
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Beasho

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Re: Foil Box Failure
« Reply #12 on: December 20, 2017, 10:15:51 AM »
I did some test gluing Divinycell with Gorilla Glue and the results suggested the Gorilla Glue bond is stronger than the original Divinycell PVC foam structure.

Note: This observation applies to the BOND, not necessarily the expanded Gorilla Glue foam. 

For my purposes all I cared about was that the Gorilla Glue reconstituted the Divinycell cassette into a form that was as good as the original.  Check the box.

The beauty of the Gorilla glue is that it expands but don't expect the expanded foam to be the same strength as the Divinycell.  I did some further testing to show that expanded Gorilla glue has a density of ~ 1 lbs per cubic foot. Slightly more than Styrofoam @ 0.9 lbs per cubic foot. 
« Last Edit: December 20, 2017, 10:24:54 AM by Beasho »

Chilly

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Re: Foil Box Failure
« Reply #13 on: December 20, 2017, 10:59:54 AM »
Thanks for the sharing your experiment Beasho. Could Gorilla Glue be used to repair a small areas were foam is missing instead of using a mixture of Micro-Balloons and epoxy to fill in a void in the foam?
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Beasho

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Re: Foil Box Failure
« Reply #14 on: December 20, 2017, 03:54:13 PM »
Thanks for the sharing your experiment Beasho. Could Gorilla Glue be used to repair a small areas were foam is missing instead of using a mixture of Micro-Balloons and epoxy to fill in a void in the foam?

Yes - HARD STOP . . . . 100%  Much easier using Gorilla Glue than Epoxy and Micro-balloons.

There is a trick.  You need to add 'kicker'.  With Gorilla Glue this is a touch of water.  I whip it in with a Dremel.  Spray a few dustings and whip the glue until it turns lighter and aerated.  What this does is to ensure the glue cures from within and doesn't form large gaps.