wavy wrote:
Just a bit of moisture left inside my sealed hatches over time has
resulted in a odour that's best depicted as "what the cat drug in".....
I know that chlorine is very bad for polyethlyene and neoprene so I'm
thinking bleach as a mildew cleaner is a bad idea.

I don't think it is a good idea to leave things sealed when the boat is
idle. Why not try scrubbing with plain laundry soap water to see if
that will solve the problem?