Actually quite the opposite. They go through the target ship and secure all the watertight doors, hatches, and fittings, just as we would when going to GQ aboard an active duty ship. (@Navynuke99 Setting Yoke? Or is it Zebra? They might also set Circle William on target ships)
Why? It’s a total efficiency thing. You want as many units–air, surface combatants and a sub–to all get a chance to shoot at it. I recall a certain CG got yelled at for taking too many 5” gun shots. The Mk-48 is designed to break a ship’s keel. It wil definitely sink an OHP-class like this with one shot…so the sub goes last. 