Does your Sunfish naturally pressurize?

[Coconut]

Hi all.
My SF is relatively new – it is a 05 model, but prior to my purchase of it, had only been used a few times. Since I have owned it, I have twice unscrewed the drain plug found on the deck. Both times, when I did this, I found the hull to be slightly pressurized as air rushed out of the hole making a very audible noise as it passed through.

First time, this happened I thought to myself – that is a good sign as it indicates a tight hull as the air inside has warmed up (in the hot Texas sun) and expanded – creating the pressure. This afternoon, when I unscrewed the plug and again found the hull pressurized I got to wondering if this is in fact a good or bad sign of hull integrity. Anyone else experience this?

More examination is needed, any comments appreciated.

 

[adavid]

Well, that should show you that your mast step is not leaking...yet.

Your hull should not be holding pressure, though. On the forward wall of the cockpit, up high, there should be a vent hole. At some point, someone may have done a leak test (where you have to tape up the hole), and forgotten to remove the tape.

 

[Coconut]

When I first read your post I did not believe that my boat had a vent hole - fortunately, I went out and checked. You are right, the vent hole is there and it was taped up. Ripped the tape off and the hull unpressurized immediately. As the previous owner did little with the boat but have it delivered to his house and sailed it twice, I do not think the previous owner put it there. I'm thinking it had to come out of the factory with the tape over the hole. Maybe a random pressure check on the assembly line, maybe they check them all. In any case, the tape is now removed - thanks!