Here are examples of open and closed cell cork. I have always found open cell cork floats in the fuel systems that had cork for a float. I don’t know what the reason could be. An internet search of closed cell cork indicate “its closed cell structure makes it very resistant to absorption of liquid. Because of that resistance, a cork will float in gasoline”. So I’ve added some to my experiment.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.