To answer the question about a hair dryer, it would not generate enough pressure or volume to do anything. The vents in the pylons would probably flow all the air the hair dryer would produce.

I agree that there should not be any pressure differential noticed when you remove a drain plug. If the hulls weren't vented you could not drain water out of the hulls under normal conditions.

About the repair on the beach that I described in the private message, the fellow who fixed my hull had a business of several Hobies that took people out for rides. He maintained his boats and had all the materials he needed to fix mine.

Howard