I tend to be big on risk reduction.
At least now...
I "ask" the navigator (and now in GW the watch officer) about the weather a fair bit.
If it is worse than light flog, I don't engage; or try to engage.
After reading that early WWII U-boat guide it warned you have to be ready to fight in an instant in fog ( I guess stuff appears suddenly

) That is my hard analysis for all this.
Had a wonderful career going, 1939...a type VIIB. Just really had hit my mark after all the hours of play. Doing all the right things including ducking out of and reacquiring tracks on convoys for a reattack. Good confidence. Just all around happy with my overall performance.
3rd patrol.... knocked out a freighter near that convoy area coming out of the west of the UK. ... not long after...picked up some sound readings: thundering herd. Went in on the surface, medium fog.... thought I would at least try and see what was going on..... 1600M away... a destroyer. Surprised, by the time I called 'Alarm!' the boat had taken some serious damage..... In the rush of things, continued with the crash dive not acknowledging my hull damage.
Somewhere around 120M the boat broke up.
All in all though a good (short) career with a good story to it.
So... in the future, I won't do combat in medium and heavy fog.