The forces involved are simple thermal expansion of the air inside your board.
As long as there is a positive pressure inside, you are OK.
The worries come when you have the board all warmed up on the inside and then place it in cold water.
The core temp drops and creates a partial vacuum inside (if your vent plug O ring is doing it's job).
If there are any open holes to the atmosphere anywhere on your board (vent plug w bad Oring or overtightened), dings through all the layers of the skin, or centerboard cover plate screws that have pierced
the inserts, then water can be drawn into the core of the board by the negative pressure (vacuum) inside.
If there was no water in at the bottom of the vent plug you probably do not have any issue with water in your board.
Hylomar (or a Permatex product that claims to be the same) is available in auto parts stores.
I would take the CB cover off and put a little hylomar on the bottom of the cover first, just to make sure that the Hylomar will not damage the plastic. It's a super strong sealant (kinda expensive, but worth every penny when you need to really seal something) and putting a little around the screw holes, and on the screws should seal up any potential leaks for good!
You could use some marine caulking compound as well, but stay away from silicone based products.
Silicone anything is not what you want around your boards and rigs. Once applied, it creeps into everything at almost a molecular level. Once in, there's no way to get it out or ever make anything (paint/
adhesives/primers/ conversion coatings/phosphatizing/etc.) stick where the silicone has been.
We used to bake aluminum castings at nearly their heat treating temperatures to try to "boil off" silicone
sealers that the uneducated had applied. This worked some of the time.
Hope this helps,
Last edited by Roger; 24th September 2010 at 08:40 PM.