Hi
Just on my way to build a Sup Foil board, I aim to get a lightweight board and heavy reinforced US box for the foil.
Is it needed to have a stringer in these short thick boards?

Aim for a 6" x 25"- 27" board and around 90-100L
Still trying to get the final design...

Cheers

Anders

Hi, looks good!
I have just finished mine. I used 25kg cm eps foam and cut a section out and used some carbon to strengthen under the fin boxes and link to deck. No stringer. Already a bit spewing as I used futures fin boxes which I have heard are weak, however no issues with mine so far. Its 6.3kg 120l 6ft 8 x 28.5 x 5 and as I'm a rookie glasser I think I have about 500g too much resin in it. I'd be interested in what weight you aim to end up with?

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Yeah, I could not find any EPS so I went with Polystyrene XPS board. I think I will cut in 2 stringers above the boxes and router out for the boxes. They can go through to the deck above. then high density foam around. Glass and carbon reinforced should do.

Wasn't sure if a full length of stringer is needed on the short thick board.

Like your carbon deck! Is it kevlar on the rail?
No idea of weight but just as little as possible

Its double bias carbon + 6oz glass on the deck, and basalt rail tape for the rails. That basalt is so easy to lay up. It's all from sanded.com.au
Goodluck with it, I'm so stoked with mine!

Good idea and job. Must be care of delamination with XPS because of epoxy doesn't stick on it. I heard about the necessity to make pinholes all around the board to let the air blows out.

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Kami said..
Good idea and job. Must be care of delamination with XPS because of epoxy doesn't stick on it. I heard about the necessity to make pinholes all around the board to let the air blows out.

Glass it late arvo when the temp Is dropping, doesn't matter for the first layer either top or bottom,
but once one side is glassed,
glass the other side with temp dropping or vac bag it any time of day.

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scubaste said..
Glass it late arvo when the temp Is dropping,

You are speaking of EPS. XPS is different as it is totally water and air proof.

The issue is after some use of the board, I guess from various pressure compressions or degasing of the blank, some air bubbles appears between the glass and the foam and have nowhere to go, and will tend to push as a wedge to delaminate the glass.
Shapers working with XPS have developed tricks to better anchor the glass into the foam (roughing the blank), or even drilling pinholes in the finished board glass itself every cm to let the air out if it forms... since the foam is waterproof, water entering the holes wont be an issue.

I haven't worked with XPS before but I had a quick go with the sandpaper and it it shouldn't be a problem. Good to know about the trick to perforate with holes to increase the bond. I will have the board done with carbon and glass also do a vacuum bag so it should be 100%

I am just to insert 2 short 6mm ply stringer over the US boxes. And they will go through to the deck.
2 leach plugs aswell

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anders884 said..
I haven't worked with XPS before but I had a quick go with the sandpaper and it it shouldn't be a problem. Good to know about the trick to perforate with holes to increase the bond. I will have the board done with carbon and glass also do a vacuum bag so it should be 100%

I am just to insert 2 short 6mm ply stringer over the US boxes. And they will go through to the deck.
2 leach plugs aswell

Sorry about Ander, pinholes are not going to increase the bond, they will allow the air to go off through the skin otherwise it will delaminate from the EPS core promptly as Colas did explain up here.

I got some cheap eps so now spent a grand or two on supplies to make marginally crappy, clearly diy boards. It's funny because it's TRUE. ;-)

But no regrets...always wanted to try and the only way i learn is by mistakes.

Once shaped you can level it off with spackle. Then seal with a layer of epoxy and lots of micro baloons. Otherwise you will ding it like crazy while working on it.

I used chinook boxes...supposed to be strongest, has glass fibres in it not just plastic.

I vacuumed on a layer of divinicel on deck for strength....but adds a lot of weight.

Added carbon and kevlar to rails...bullet proof for paddle hits.

2 layers of 6oz is overkill....2x 4 and 6 is good.

Carbon is tricky to work with to get nice even lines and no loose strands.

Opaque tint is still translucent. Didn't cover up my ugly errors. If I could go back in time...spend the time on painting before glassing.

Hot sun leads to eps off gas and delam. Add vent.

Now on board number 4 and each one improving a little. Good times.

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Kami said..

anders884 said..
I haven't worked with XPS before but I had a quick go with the sandpaper and it it shouldn't be a problem. Good to know about the trick to perforate with holes to increase the bond. I will have the board done with carbon and glass also do a vacuum bag so it should be 100%

I am just to insert 2 short 6mm ply stringer over the US boxes. And they will go through to the deck.
2 leach plugs aswell

Sorry about Ander, pinholes are not going to increase the bond, they will allow the air to go off through the skin otherwise it will delaminate from the EPS core promptly as Colas did explain up here.

Oh I did some research and didn't found anything on the gas and delaminating issue of the XPS Polystyrene. Now I can see that that is the case.. Not great. Not really interested of drilling (small) holes throughout the finished carbon deck ??????

If anyone have pictures of experience of the above it would be great to see or hear more.
Will do some Google for now.

And thanks!

Cheers

Anders

I have followed this guy's how to series. He is not super pro , makes some errors, but us ahead of me. Good step by step....I have found it helpful

Xps

www.youtube.com/playlist?list=PLHeE1mcmnNBQ00siGWuGXLIjvFkLY0B1P

Eps...final video is adding a vent after bug delam
www.youtube.com/playlist?list=PLHeE1mcmnNBSXs0ymSgrxwF5od6gqvX07

Apparently delams on XPS/XTR always happen, but not immediately. You can build a board normally and think it is OK, only to have it delam some month afterwards.

Note that the trick of drilling holes in the glass may not be compatible with covering them with a pad...

Another solution is just to ... not glass the XTR blank at all :-)
(Of course it is just for a demo, it wont last long)

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juandesooka said..
I have followed this guy's how to series. He is not super pro , makes some errors, but us ahead of me. Good step by step....I have found it helpful

Xps

www.youtube.com/playlist?list=PLHeE1mcmnNBQ00siGWuGXLIjvFkLY0B1P

Eps...final video is adding a vent after bug delam

>

Yes seen some of his videos.

I will add a few vent plugs. Guess I could drill a 3-5mm holes pattern through the finished board to be 100% sure.
Time to start shaping the block! Exiting times ahead