Ending at La rochelle (spoilers)
The sub pens were almost bombproof. Why would the sub stop
outside? I believe the RAF patrolled the approaches to La Rochelle and St. Nazaire; I would think a returning sub would get inside the pen ASAP.
I know the allies bombed sub pens in France and Germany, but I think the only
somewhat successful raids were by heavy bombers, sometimes with "block-buster"
bombs.
In the movie, the "bombers" looked like low-flying single engine planes. Does the book explain any of this?
It won't chip, peel, blister, crack, flake or rust in any way.