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[wouter]

Read quite a bit on sways on the cs
but am stll wondering what its most common failure areas are.
rails ?
fin area ?
what are problems you guys encounter?
anyone had a waterlogged board yet?
What is the name of the water proof foam again?
Wouter

[paul cannon]

ive water logged a few
that seems to me to be the only problem

[Jarrod]

You don't plan to fail, you fail to plan.

Whatever that means.   

Seriously though, I've never had a failure.  Guess I don't push them hard enough.

[Benny]

My failures have been compression splits in the deck from either hands (pop-up spot) or knees (knee paddling).  The single layer of glass over the balsa isn't up to the tension task of pressing in on it so many times, and the joints between the pieces of wood eventually opened up. 

The causes:  single layers of glass over & under; balsa skin just taped together for bagging onto the blank. 

The solutions:  additional glass over (or CF under); sealing the blank with epoxy / microballoons under for strength; gluing the pieces of balsa together prior to bagging and not relying on the glass's epoxy to also join the skins together.

Result: No failures in over 2 years. 

[wouter]

to benny

Thank you for the tips, i already have pictures, but not the upload cable, so more coming soon!

With 1 layer of 3 0z and 1 layer 6 oz, would it be the best to put 3 inside ..on foam.. 6 outside?
That would give me a bigger layer of water barrier  (cannon) and more compression resistance too if i do that on top. Bottom would then be the reverse? 6 inside 3 outside, but less protection for water... mmmm.

how much extra glass do i need under me hand AND feet?  Do i combine this with the use of microballoons all over top?

Do you guys reinforce some areas with extra wood?

Wouter

[Benny]

Hey Wouter,

I'd just add some little extra patches of glass under the skin in spots you know will have pressure.  Your back foot probably occupies a small area most of the time, and your hands too, on popping up.  Maybe one in the middle too, that would protect from both front foot traffic and your knee on duckdiving. 

Measure out from your current board's wax smears where the patches should go.   

3 oz or 6 oz for the patches, neither one's going to add significant weight.  Use a piece of plastic to wet them out, and then transfer them to the blank, either before or after the one solid piece of glass that goes under the skin.  Wetting out & squeegeeing elsewhere makes sure your resin ratio is super low - better for strength and saves weight too. 

Yes, seal the blank.  Adding anything to the resin is probably a waste of time, though, unless your beads are super huge & soft and there are tearouts everywhere.  But if its smooth, just warm your resin and use a squeegee or a firm, small paint roller.  Press hard - you want it super thin, and you don't want to have to sand it.  Foaming or whatever other cosmetic problems happen with epoxy when you move it too fast or too hard aren't an issue when you're hiding it under skins.   

[paul cannon]

i just want to add that 3oz under and 6oz over should be dentproof
i cant dent any of my boards with that schedule
in fact ive got boards that are 2oz under 3oz over that are very difficult to dent
it may have to do with skin thickness
the compressive strength of 1 to 1.5 mm balsa is far less then say 3mm
also the wood density and type is relevant
also 1# foam will spring back more then 2#
while thes suggestions are a solution
they are not the only solution

[Benny]

You're right, Paul.  My fixes are specific to my large supply of balsa (1/16") and glass (4 oz e). 

If I was buying just enough for one board at a time, I might have approached changes differently.

One of the best things about composites is how many different ways you can fix the same problems.   

[paul cannon]

hey benny
ive made a couple of boards out of the thinner wood
and my finding were similar
one ended up getting patches
but the board had a great feel to it
if i had a thicknesser id be playing with thinner wood like paulownia

[Bernhardt]

the most common have been the ripping out of unsupport probox bases and other forms of water intrusion do to bad sanding, skin fabrication and overall laziness. I've had several delams with the bamboo as vacumming on the deck skins can be tricky if you tie down the edges with tape to hold it in plaace while you bag it. The tape doesn't allow the deck to press down as wellbecause the rail are pinched by the tape.

What I do to compensate now is to use a strip of bubble wrap in the middle of the deck to help apply pressure to force the center of the deck skin down as the bag compresses out..

I've lost alot of expensive fins  with these probox blow outs. The early ones were from the exotherm melting of the foam but all from no support. 
 

[Jarrod]

Hey bernie, what's up man?  Good to see you here.

how are the boxes holding up on that board I sent out?  It was my first time using Probox, so I'm kind of curious if my overkill install has been as foolproof as I had hoped.  Has it been getting enough watertime to even start stressing it?  How about the rest of it, still watertight and in one piece?

[Bernhardt]

Aloha Jarrod
the boards been holding up well
been a sucky surf summer
I've been using the custom g10 keels Griff made for my firewire where the plug are way forward allowing the fin to sit further back from the box and to twitch a bit like Rasta's Van Straalen's fins I guess. I traded the firewire fish in with Barnfield for a 6'8" Alternator instead. I showed Carvenalu and Bill your board when we went up to do the trade and they said it was beautiful craftmanship. Just a tad chunky for their tastes but they surf northshore and I surf places like barbers point.

So so far so good on those probox's
I hope Alaska has treated you well..

Been playing alot with the blue stuff(we call it "Bambloo2")  before we move on to hollows and roy's 13' monster. Also been doing alot of stuff in cedar, paulownia, and wiliwili eventhough balsa is definitely the easiest to work with in the end. Having your own bandsaw and thickness planer opens alot of possibilities. Just wish I had a 24"-30" drum sanders to make the perfect skins.

take care