unsinkable?

Looking carefully at the boat, looks like the inner hull would float like a bathtub if there were a hole in the outer hull. BUT! without drain plugs in the fish boxes & engine bilge in the deck and the storage compartment up front sealed off, (and any other misc. holes between the two hulls) the water would eventually fill up the inner hull and down she goes.

The boxes in the deck (three in my boat) would have to fill up to overflow into the bilge to be pumped out. Once it's there, the pumps would have to keep up with the rate water is flowing through the box drains. I wonder how high against the inner hull the water line would get before it equalized. Would it make it high enough to reach the storage compartment up in the bow? I'm just thinking out loud...