Air Pressure in Hulls

I have one Hull on a late 70's H16 that always has positive air pressure when I remove the drain plugs. It never has any water in it but I have read that having this positive air pressure is not a good thing. I intend to look at the pylon's when I take it appart this fall but can someone help me out with what exactly I am looking for re. the vent and how to best fix this?

There is a plastic tube that passes through the plyon seal plug. Just make sure the tube is clear and the casting is not sealed to the post in some way.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Responding late and overstating the obvious, when returning from a sail make sure to open drain plugs to let hull breathe, is a pain but will save your hull in the long run - delam decks are easy to repair but have found the hard way that the sides of the hull begin to delam - not good. Can be repaired at great cost and weight, plus you never sail the same way after knowing the hull has been repaired.

I also have a hull that had pressure on it after sailing for an hour. I posted the same question on another forum and was advised to just open the plugs after sailing and don't worry about it. The thing is, the cat is a 2009 and brand new. You could even smell the resin from the air that came out. If this is not right then I want it fixed by the dealer while it is still under warranty. I thought that there was a tube in the pylon to vent to the atmosphere. Is this really something to be concerned about?

I've occasionally noticed some air pressure build up in the hulls as well when I remove the drain plug after sailing. It's usually a very light woosh, very little pressure. It's most likely caused by the change in temperature (and hence pressure) of the hull, particularly when the air is hot and the water is cool. If you sail for several hours, the air in the hulls is going to cool to approximately the temperature of the water and the air pressure inside the hull will eventually equalize. Then you bring the boat up on the beach, de rig for 1/2 an hour or so and the hulls heat up and the air pressure inside increases. But since the pressure relief hole in the hull is so small, it takes a while for the pressure to equalize. You have to consider that the hull is quite a large volume of air and the relief hole is only about 1/8" diameter.

If your hulls don't leak water and they only build up a modest air pressure, you should be fine.

sm