Yes, that's the guide I found. It's great, but the in-game one would be even better. GWX does not seem to feature it, but some of the youtube plays seem to feature it with the Aces of the Deep mod.
I was hoping there was a simple 'enable vulnerabilities for GWX' mod that I had missed, but I guess that isn't the case.
Just curious, does anyone know why GWX decided to feature deck guns on merchant ships? Is it historical or..? I really enjoyed punching holes, and my poor deck crew ends up .. well.. seriously wounded at best.