Sam beat me to it.. I was going to suggest you make sure you remove your head from the hood before you punch the holes in it.
I had this same thing happen with an unvented hood I owned. Put holes in it and it was fine until it blew off the dive boat one day.
I had this same thing happen with an unvented hood I owned. Put holes in it and it was fine until it blew off the dive boat one day.