Several years ago, while cruising along Newfoundland, Canada's south coast — where there are few ports and fewer chandleries or auto-parts stores — I was faced with a leaking heat exchanger end-plate gasket. An impeller failure had forced the removal of the cover plate for cleaning, and in the process, the gasket was damaged. No amount of "form-a-gasket" (more on this in a moment) would hold up in the damaged area for more than a day of running. Ultimately, after turning the boat upside down for suitable material from which to make a gasket, I used the cover of the HO 249, the sight-reduction table. It was nearly the same thickness as the original gasket, and once slathered with sealant and compressed, it remained liquid-tight for the remainder of the passage. It wasn't a perfect solution, but it worked until a proper gasket could be sourced.