When I was a kid my dad had a 24' wood cabin cruiser with a 4 cyl inboard Gray marine engine. One day the engine died during fishing for blowfish. The copper 20 (?) gallon gas tank had collapsed (vacuum sucked it near flat) - we discovered mud dabber wasps had filled the tanks air vent out the sided of the boat with red clay. Poked it clean and fortunately engine restarted. Weren't any Tow Boats US in Barnegat Bay NJ back then (and hardly any Blowfish now)!