Re: hull vents?
 

Yesterday you mentioned your concern about your scuppers. You'd be amazed at how much water was seeping in through my thru-hull scuppers. And they looked fine... And yeah, there is a lot of space under the floor. Brochure on 21 said it had 20 cubic feet of dry storage under the berths. That's more room than my refrigerator... So yeah, your vessel will hold a lot of water...

Seek out the problem as No Bones suggested, before the problem gets bigger. Good luck and keep us post on your findings.

Re: hull vents?
 

Those aren't vents...they're scoops!