yeah, i've never had my hulls make the air release noise either, that's just what i've heard other people say. In theory yes in order for water to drain out of the plug most efficiently there needs to be air comming in from somewhere else. However if seems like if your hull was so well sealed that pressure was equalizing then it would never take on enough water for this to be an issue and the little bit of water if you ever took any on would still drain out in a fairly short time. With this taken into consideration, do you think it's a bad idea to try to seal above the pylons?