speed633 wrote:
The poof means your hulls are completely sealed. With even a small leak you wouldn't get this.
I disagree. The poof could also mean that the hulls are vented but just haven’t equalized yet. I have noticed several times when opening the drain plug (particularly on a hot day, and shortly after hitting the beach) that I get a poof of air coming out followed by water. If the hulls were completely sealed, then there would not be any water getting in. So the only explanation (that I see) is that the hulls have a small leak that is enough to let water in over the course of several hours on the water, but not large enough to let the air pressure equalize quickly after a rapid temperature change.
In any case, I fully agree that plugs should be opened whenever the boat is not being used. Even if the vents are open, you still want as much air circulation inside the hulls as possible.
sm