Hi All
I stopped surfing in 1965 ( - Midget Farrelly as World Champ - ), so am not up with the latest surfboard technology 
I recently bought a surfboard with a Salomon S-Core inside, to use as a kite board. I have been told conflicting information about when to open the vent in the deck. Haven't had much luck researching it on the internet. Can someone please give me the real story??
I can understand needing to open it to dry out the core after a ding, or during aircraft flight. What about during storage between sessions? Can't imagine having to remember every session to tighten the vent before going in the water, and loosening it after each session....sounds like a recipe for a "Senior's Moment".
Hang on ....I AM a Senior!! 
Would also be interested in whether this system is still used.
Cheers,
Hemi Tuwhaaka
There has been some threads in the windsurfing and SUP forums on it. Basically opening the vent when there is a temp. change (ie. out of the water and into the sun) will prevent the board from expanding from the pressure built up. Expanding and contracting basically breaks the bond between the skin and the core. They say even the difference between day and night temps 365 days a year is enough to cause damage. Good luck and don't forget to do it up when going in the water.
Some windsurf boards had this sort of valve for a while, its on boards where the cells are interconnected, gas pressure can build up on a hot day in the back of your car after being in the cooler water, also will suck in water through the finest of cracks after letting out the air before putting into the water..................hard to get right.
Was replaced with a breather membrane made of Goretex I think....
