Author Topic: Best way to mount the foil boxes and footstraps on a wingboard?  (Read 5473 times)

kwhilden

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So what's the current best practice to mount foil boxes on a wingboard build?  For maximum strength and longevity, given all the extreme forces? 

Can you buy boxes made specifically for foiling?  So they have extra strength? I've heard of custom carbon fiber boxes...

I'm planning to design a wingSUP and build it at my buddies SUP factory in LA. He's very good at vacuum bagging carbon fiber, but I wouldn't trust him to get the physics right on a foil box installation.

Also, do you all recommend using 1lb EPS foam?  Or is 1.5lb foam better for maintaining structural integrity where the foil boxes connect to the foam?

Regarding footstraps. How are those installed in a structurally sound manner? Are there inserts that can be purchased?

Thanks all!

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PonoBill

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #1 on: April 02, 2022, 08:10:50 PM »
Cassettes are available for tracks. Or you dig into the build section and see how folks are doing it and pick a way. I prefer a big chunk of PVC foam a little thicker than the board. Gorilla glue it in place flush with the top, route it flush with the bottom. Route the slots for the chinook boxes, and gorilla glue them in place. Two layers of carbon top and bottom over the PVC and a few inches of the EPS with toothpicks through the carbon at the corners of the tracks, then build as usual.

I'm a fan of NO inserts for footstraps. they're a leak waiting to happen. I use NSI stick-on inserts.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

kwhilden

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #2 on: April 03, 2022, 07:10:56 AM »
PonoBill... thanks for your comments.  The NSI stick-on footstrap makes so much sense. Especially since I'm not going to be doing airs.

A couple of questions.  What density of PVC foam do you use?  Why do you like it vs standard yellow HDPE foam? 

Looks like Fiberglass Supply sells cassettes: https://shop.fiberglasssupply.com/Hydrofoil_Foil_Board_Part-Foil_Boxes.html

However in thinking about the physics, I think it does make sense to custom make a cassette that matches the thickness of the board. So the forces applied by the foot on the top-skin are tranferred without a layer of weak foam underneath. 

Couple more questions...

What about using a stringer of some kind (HDPE foam or something else) that runs from the foil block to the front foot placement?  So the force of the front foot is better transferred to the foil itself?

Have you experimented with 1lb EPS vs 1.5lb EPS?   Is 1lb too weak?  Or is the weight difference significant in such a small board? 

Thanks for your thoughts!






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surfcowboy

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #3 on: April 03, 2022, 08:01:08 AM »
More on this later, I gotta go foil. But check my last 2 build threads. I did some things you mentioned. Blue foil SUP and then my orange prone board for a weird one (don't bother with that.) And I'll post pics of my "Dwight Box" pillars today too. There's a lot in several threads here. Search the latest gorilla glue thread.

kwhilden

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #4 on: April 03, 2022, 04:03:51 PM »
I saw my shaper surfing this morning. 

He says that lately he's building foilboards with dual wood stringers and routing the foil boxes into the wood. 

It's a little heavier, but it's also the strongest and most reliable long-term.  He says any option with HDPE foam blocks eventually starts to break down the EPS where it contacts, and fails.

He also told me has a blank in stock. Dual-stringer 1.5lb EPS foam. 

I guess that's a bit heavier than stringerless, but I do like the idea of reliable strength.

So I guess I'll get started on designing my board in Shape3D.

Any thoughts on this are welcome. 
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surfcowboy

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #5 on: April 03, 2022, 04:22:42 PM »
I did that on the orange board and it's nice. It's just a lot of work. In the end, stringers are good. Don't sweat the weight. The 1.5 is what most people use.

kwhilden

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #6 on: April 03, 2022, 04:58:34 PM »
yeah cool.  Now I can start messing around with design theories on Shape3D.  I'll be sure to share them here. 
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Dwight (DW)

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #7 on: April 03, 2022, 06:36:21 PM »
I saw my shaper surfing this morning. 

 He says any option with HDPE foam blocks eventually starts to break down the EPS where it contacts, and fails.


True. Because most don’t tie it to the deck. People love to take the easy way out. Stick in the 2 inch thick blocks they sell for tracks and call it a day. I don’t care how many layers of carbon you slap over the tracks, if it’s not tied to the deck, you are counting on the bottom skin of the board not flexing, EVER. It will flex, and then the block wiggles, and the board breaks down inside and fails.

kwhilden

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #8 on: April 04, 2022, 07:46:39 AM »
Thanks DW for your thoughts.

Here's another question.  Does the front two feet of the wingboard need stringers?  Could I stop the stringers just past the standing area, and then save a bit of weight in the nose? 

Or would that create another likely breakage point? 

It seems like the forces between the nose of the board and the front foot are much smaller in comparison to the rest of the board, and this is an opportunity to reduce swing weight. 
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Dontsink

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #9 on: April 04, 2022, 10:29:21 AM »
I am making a very small dockstart board, it will have two partial wood stringers from the foilbox up to the front foot position.Boards that see a lot of pumping suffer a lot of fatigue.

kwhilden

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #10 on: April 04, 2022, 06:28:33 PM »
Thanks all for your comments. I've got some pretty clear ideas on how to construct the board, and I've just started on my Shape3D model.  I'll post it here soon.

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surfcowboy

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #11 on: April 05, 2022, 08:26:14 AM »
Mine stop at the feet. It's technically a break point but we ain't charging Jaws here. 🤣

PonoBill

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Re: Best way to mount the foil boxes and footstraps on a wingboard?
« Reply #12 on: April 05, 2022, 03:28:26 PM »
I did full height 1/4 marine ply two-foot stringers on both sides of a homemade PVC cassette. I suspect that setup will be still solid when cockroaches rule the earth. But it was a stupid amount of work contouring the plywood to the surface of the board. I've seen a million solutions to the issue to date, some of them ridiculously bad. the bottom line is--as DW says, you have to tie the top and bottom surfaces to the cassette. You can't rely on the EPS to hold them in place. If you do that the EPS doesn't matter--it's just there to hold the top, bottom, and rails in position while the epoxy kicks, so I use 1#.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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