Off topic but close enough. My father was given a fancy bass boat that had been sitting in a barn for years. We tuned it up and headed to Winter's Park to test things out. It would really move and seemed perfect for the first couple of miles. Then it seemed to start losing some power. By the time I got back in, I had all of my passengers as far forward on the bow as they could get and the fuel tank was completely under water.
All but one of the old thru hull fittings had snapped off leaviong multiple holes in the hull. Those plastic thru hull fittings age and decay sitting dry. We had to replace all of them. West Marine sells a bag full of different sized plugs just for that possible problem. Never go out very far without having a plug for every hole in the hull!
In our case, the boat was pretty much unsinkable to begin with and all I had to do was keep her level and get back to the dock. Still, when the water started coming up thru the floor drains, it was not a nice feeling!