Yeah, I'm aware of decks awash and all that, and generally how U-boats operated. I'm not new to the series, played SH3/4/5 a bunch years ago. (should've perhaps made that clear in the first post)
I'm just not familiar with all the changes TWoS and the mods incorporated make.
Good to know O & S straits is doable.
I shall keep you posted how it went.