r2908 said...

Ps its that really colourful homo looking board if that helps

If it is an RRD, that does not narrow it down at all

I don't recall hearing about closed cell foams, they did drop carbon and kevlar and ONLY use biaxial glass around about then so maybe that is the change you are thinking of?

I have a 2011 Wavecult, and the blurb does not mention any special foam/s etc. Makes it hard as all their literature is Y12 Y13 etc, but I am sure I have the right specs .pdf as the paint job is the same.

Mine is the single and they do feel heavy - and particularly heavy at the back. They used the same shape for single and quad, so I strongly suspect that most of the last foot is all d'cell block!

I can't weigh mine right now and RRD's .pdf I have does not specify weight hmmmmm. But mine is a 92 single anyway, so may not help much.

Def all glass though

Has it got a bung? That's the big give away, if it's got a bung, it's open cell, (unless it's a stony custom built for a euro, he was telling me some of them insist on a bung, they just don't understand the significance of closed cell construction) if it hasn't it's probably closed cell, ( some NZ styro techs don't have bungs).

Unfortunately closed cell styrene (extruded, not expanded) is heavier and more expensive. It's designed as insulation underground supporting concrete floors, so it needs to be dense enough for load bearing, and closed cell so that it doesn't absorb water, which would compromise it's insulating qualities.

Closed cell urethane is possible, it's how Stony builds his boards. But that is also a bit heavier and the blank has to be blown very close to the finished shape of the board, as the density varies through the blank, being more dense near the skin. It's just so much easier to have a huge block you can hot wire any shape you like out of.

Decrepit,
My limited knowledge regarding extruded polystyrene is that whilst its closed cell it does off gas and can delam initial layer if gases build up excessively in localised area. Appreciate if someone could elaborate.

sausage said...
Decrepit,
My limited knowledge regarding extruded polystyrene is that whilst its closed cell it does off gas and can delam initial layer if gases build up excessively in localised area. Appreciate if someone could elaborate.

Haven't heard that before, I've built a couple with no problems, Both still in use 10 years later.
Maybe being transported here by air, in a reduced pressure hold and sitting in my hot shed for a while got rid of any excess gas?
Rider5 has also built a few, And I haven't heard of any problems with his.

I'm convinced that they are , its got the same balance point as the stone boards (other 7kg+ boards have heavier tails, fanatic etc ...) . Same weight per liters , it was around the time companies were experimenting with that pu foam . If you press your ear up to the vent hole it never makes a noise (open cell boards even with minimal water inside do like a sea shell) .. also I'm sure in that vid, a new foam was talked about .. cheers anyway .. ps anyone snapped one ??

Hmm mine doesn't hiss either. You are making me wonder now

I was maybe going to make it a thruster one day.......... but the board is pristine so don't wanna router it just yet!

How about a few drops of water in the bung hole, wait a minute, then turn it upside down and it it runs out it is closed cell. ?

Good idea mark ill try that next time I sail and ill post .. could be awhile though ... If you try it b4 please post ... Thanks

EPS, expanded polystyrene IS closed cell foam,
en.wikipedia.org/wiki/Polystyrene
It's beads of closed cell foam pressed together, the water gets into the spaces between the beads, think of a jar full of glass beads and water, plenty of water gets in there between the beads.
It's lighter than the other kind of SOLID closed cell foam like XPS which is prone to delaminate. One surfboard company makes XPS boards with little breather holes all the way around the board, water WILL not soak into the foam but the gas needs to escape.
On the other hand water soaks into an EPS board like a sponge even though the foam is closed cell.
Some unscrupulous dealers will make claims about using "closed cell EPS foam", insinuating that water cannot soak in.

decrepit said...

sausage said...
Decrepit,
My limited knowledge regarding extruded polystyrene is that whilst its closed cell it does off gas and can delam initial layer if gases build up excessively in localised area. Appreciate if someone could elaborate.

Haven't heard that before, I've built a couple with no problems, Both still in use 10 years later.
Maybe being transported here by air, in a reduced pressure hold and sitting in my hot shed for a while got rid of any excess gas?
Rider5 has also built a few, And I haven't heard of any problems with his.

Ditto to the 10 years plus!, strongest construction out that I've ever used, shame everyone whinges that it adds a whole 1 kilo. No delam issues with a stiff sandwich covering it. Oh also doesn't turn into a 15kg board.

The only windsurfing boards not EPS styrofoam are custom made (except some BIC boards)

Look into the vent hole of any SUP or recent windsurf board, white Styrofoam beads.
Closed cell like XPS is too tricky for those little asians to make correctly and it's too heavy, they don't care if it's a sponge.

I look into the vent hole and its black ??

r2908 said...
I look into the vent hole and its black ??

Probably from drilling thru the resin (which is black tinted) ..... after the breather is inserted they run a drill thru to be sure it will vent

EDIT got too curious mine was also black. A bit of poking reveals it to be dust sitting on top of the foam. Tried to dig some core foam out with a screw to no avail.

Mine is 7.3 - 7.5kg bare (depends how I measure it), so yours at 7.5 for a quad sounds right.

OK WARNING!!!!!
be very careful with this!
If you seal a short plastic tube to the vent hole with some sort of mastic, you can GENTLY blow or suck into the tube. If it's closed cell, you'll only move the air in the tube, if it's open, you'll move the air in the whole board.
The difference should be noticeable.

But blow too hard and you could loose the bottom of your board!