Here is a GREAT blog post with pictures on how to check for a leaky boat!!!
http://victoriakayaker.blogspot.com/2009/06/aaaarrrrrgh.html
pressure checking hatches/compartments
I’ve seen and done the same thing done but with a shop Vac. Nice part is that after you find the leaks, you can reconnect the hose to the suction port and suck in your sealant of choice.
pallen
New Necky composites have all
hatches air pressure tested at factory AND upon delivery. Good blog there!