Hi

i see if i can help you here. Firstly with the olympic class liners the bulkheads wasent toped meaning once water reached a certain hight the water was able to flow freely into the nexts compartement. in comparason the watertight doors did they jo the design had many floor's in the design

secondly vents werent watertight neither. I have seen a picture of the watertight doors aswell but never the ones on the upper decks. Aswell the damage receive to the titanic is said to be that of a fumb but in diffrent compartmens because of failed rivets.

There is far more they could of created in the olympic class and they didnt the bulkheads could of gone higher but the highest ive read was only as high as e deck a few feet above the waterline. and some below the forcast deck.

the lusitania had far more safety features as they had an inner skin. aswell the water tight bulkheads went higher but we all know what happand there

hope this is off help