Mac G, you're right about the first four compartments being flooded before there was a serious problem. And I'm not sure, but I think I have a theory about the compartments and how they operated. I think it had to do with more of a weight/balance ratio. For instance, if the first two or three compartments were damaged, the weight of the rest of Titanic would hold the bow up enough, despite the weight of the water, to keep the "ice cube tray" effect from happening. Not to mention, Titanic also had pumps to help handle any excess water that might pass through vents and whatnot. Once 5 compartments were compromised (possibly 6 if you take into account the water rising from the floor in Boiler Room 4), the weight ratio was more than Titanic could handle, and we all know what happened from there. Again, this is just a theory.