cranky said...
Thank's Dean, any ideas on the cause?
I dont have any idea how the board is made but, its obviously caused by air pressue being lower outside the board.
An area of poor lamination between skin & foam, then air from the eps has made a blister.
EPS is mostly air, so even changes in atmospheric pressure will cause a differential in & out. A low pressure weather system over the area or going from sea level to a higher altitude.
Is there a bung/vent in the board? Again easy to fit one, just a small stainless self tapper with an O ring under the head will do.
Or a bush mechanic would use a 2" nail to belt a hole in the tail near the leggy plug then put a small bit of duct tape over it

Cheers
ps one thing I would check......the blister looks like it is in the center of the bottom?
Support the nose & tail then put weight on the deck to make the board flex, at the same time check the blister, it could be the start of a crease?