I've only noticed this when re-loading a submerged save (not a good idea). Wasn't sure whether anything was actually degrading/breaking or whether it was just a glitch...

Anyway I avoid submerged saves now due to other odd behaviour like missing tonnage, sunk ships that are afloat again but not allowable targets etc.

That's strange cos I never save whilst submerged :hmm:
It's a good indicator though that your boat is damaged :arrgh!: