^^^ CJW I don't care about the math, in every Cobra-made board I have seen with major damage the big crease started from an area where the glass was not fully wet out. It is a fact we are paying for boards that are missing glue. What makes them strong is the laminated construction. If a bit of glue is missing I'd rather give it every chance not to have internal pressure fluctuations no matter how small. That little unglued bit is gonna get bigger and bigger and bigger....



To other who say it is too hard - Screwdriver lives in box next to mast base. Board comes out of car, reach for mast base and screwdriver every single time. = no forgetting.
You only forget once and you learn from it

Exocet were clever : the vent plug is in front of the mast track, harder to forget when you insert the mast base !

Deano said...
When it gets bloody hot, sits on top of a dark coloured car, sits in a hot shed, sits in a hot car, when ever it flys. Heat wave on the way from WA, open those vents.

Deano

Accidently left my precious Fanatic Falcon under the tarp of the ute in the sun once. When I remembered it and let go the plug it hissed for close to a minute like a cornered cat. Sailed it for another 4 or 5 years before it showed signs of delamination in the stomping zone.

The fact that delamination usually first appears under the feet suggests that leaving the vent done up is not the primary cause of delamination.

I know nothing about board construction. Agree, Delam under the feet is not a vent issue. It's where you stomp on it to jibe or should be. I have had many boards soft under foot but delaminate the bottom in cool and hot climates at a later date. Some lasting less than 12 months total. Driving hard into chop for hours on end & jumping will delaminate a light weight board, valve opened or not after use. You can even feel them go all squishy if they let go while sailing.
You have nothing to loose undoing the valve unless your forgetful
Cut a few boards in half in several places after delam and you will see multiple construction issues as Mark suggested. Mine have always separated about 5 to 10 mm into the blank not at the contact point between lamination & foam. But I have seen egg shell thick rails not laminated to the foam not be the point of failure

Deano

I asked my local board repairer this same question.
He fixed a cracked rail on a board that blew away from me when I turned away from it (I didn't use the board after it happened). A couple of weeks later when the board was ready, he said water was weeping from the crack and advised me not to have the vent open in the boardbag because of the high moisture content in the bag.
I use to open the vent before but not anymore, and definitly remove the screw if it's going on a plane.

barn said...

d1 said...

CJW said...
It's honestly way more trouble that it's worth, for all the reasons listed above by anyone with half a clue

Yes, half a clue... Here is the viewpoint of someone with more than that - scroll down to "Q: my board has a vent plug. Should I open it when I'm not sailing?"): boardlady.com/faqs.htm

Board Lady doesn't know everything, especially when it comes to pressure. Because she thinks pulling a partial vacuum on a board will evaporate (boil) the water inside. That's less than half a clue.

Anyway, bungs are the worst thing ever. First, there's no washer, so the O-ring is twisted and distorted every time you tighten it. Then there's all the sand and salt that gets in there fudging up the seal.

More importantly, why the fark do companies put the bung at the mast track. Put it at the nose or the tail so you can actually get the water that bungs inevitably leak in, back out.

I've sent this info graphic to all the major brands, clearly pointing why the bung is always at the bottom.




We should see bungs correctly installed for the 2014 boards.

Ever thought of being a cartoonist Barn?

decrepit said...

Ian K said...


The fact that delamination usually first appears under the feet suggests that leaving the vent done up is not the primary cause of delamination.

Exactly, if the pressure is spread evenly over all the board, it doesn't need very strong glue to hold it all together. (And you can't compare external pressures to internal, the internal pressures are working against the glue, the external aren't)

However, it only needs one little weak spot, (Mark's dry lay up or Ian's, use stressed foam) and any internal pressure will start the delam bubble happening. Once this has started, any external pressure will compress the bubble and spread the delam.

As I said it's a lottery, there has to be a better answer!
I agree with the comments about plugs being a major p---off. I thought gortex was the answer, lets air past but not water, however I found one plug that had been wet on both sides would not pass any air in either direction, even after months of drying.

So I think the best idea is get into a routine, even if you think it's not necessary to loosen/remove bung, do it anyway every time, then you won't have to remember if it's done up or undone.

BTW if you only loosen the bung, don't transport it upside down, the b$@^%y thing will fall out, unless you use one of Elmo's oversize rings, that jams against the wall of the insert and the bung shaft.

Or if you do make sure tis in a board bag..

Problem solved. Buy a Carbon Art, Plug is at the tail (Keeps Barn happy), No screw to undo (Keeps the forgetfull happy) and it breaths through the Gortex(Keeps board happy)

5kgs !!!,, why do they use open cell foam in the construction and not closed cell .. ?

My boards live in my van. I was a "leave the plug done up" guy until my good ol' Naish freeride board totally delaminated on the bottom..Now I'm a "undo the plug" kinda guy.

r2908 said...
5kgs !!!,, why do they use open cell foam in the construction and not closed cell .. ?

Unfortunately closed cell foam is heavier. I've made a couple of boards that way, but have switched to open cell because of the weight difference.

Mark Stone is making nice wave boards out of closed cell super light urethane.

www.seabreeze.com.au/forums/Windsurfing/Review/Stone-Surf-Custom-Quad/

They have no bung, and are sandwich construction, I don't think they come out much heavier than a standard production board of similar volume.
Trouble is the foam comes in a roughly shaped blank, so shape variety is limited, unlike a huge block of styrene.

I once bought a bung and socket for a surfboard I made, sucked water first time out, I discovered a molding line right across the sealing face. Now I check every time.

Sean said,
I remember that 15 years ago when I moved from a production board (bic saxo) to a custom, the new board was delivered without a vent.
I asked the shaper about it, he said "you want one ? no prob"
took his makita and inserted a screw in the board(no o ring).....
he told me "that's bull****, if the board is air thight there is no reason to put a bloody vent on it"

Sean, are you sure that custom of yours was open cell? 15 years ago some customs where still made from closed cell urethane blanks, they indeed don't need vents.
vents aren't there to let out water, they're there to let out expanding air.
With closed cell foam the air in the cells is trapped where it is, it can't exert any pressure on the sandwich skin.
With open cell foam, the air inside is free to roam around, any pressure build up will find the smallest weak spot and start enlarging it.

The tensile strength of foams varies in some cases it doesn't take much to free a few cells from the main body, so even with a good resin layup, there can be weak spots in the foam.
hammering through chop or a few flat landings will also weaken the foam, it won't take much pressure to start the delam once this happens.

I have witnessed a mates board explode while driving up the volcano in Maui. Sounded like popcorn cooking as the sandwich skin was delaminating off the eps core. Some valve screws need to be removed completely ! Not just backed off.
The bottom of the board was as domed as the deck when we pulled it out of the board bag - haha

R1DER said...
After repairing and making hundreds of boards over the last 20 or more years. Here's my advice.

1 If you want to keep your board for years use the vent plug daily.

2 If you get a new board every year, don't bother using the vent! unless you take it on a plane or leave it in a really, really hot car. (don't buy a used board off this person)

3 If you use a vent plug daily and a board bag to store your board. Cut a hole in the board bag above the vent.

So that just gets rid of spome heat in the bag? Will it help the wet board in bag issue?
Just got all my plugs out and was replacing the O rings but didn't have the exact size. We were going to use a smaller fatter one stretched and that would seal bettter but then it wouldn't let the air out..??? Confusing..going to buy exact size O rings Mon + order some Tabou ones..I noticed one of the plugs had the filed side and the other two didn't so they mustn't have been the original plugs..Filed the side down but I think I'll feel safer with original vent plugs..Cripes it was better when I was ignorant now I have more to worry about..

I'm not sure what's right
But I do agree with barn that having no washer can pinch & twist o ring so it doesn't seal
& so why do vent plugs get made this way ? If it is so critical; the plugs would b designed not to chew up the o rings

My plugs have the one side that is flat but if the plugs have an O ring on how does the air escape the board when the plug is loose?