Although the watertight bulkheads extended well above the water line, they were not sealed at the top. If too many compartments were flooded, the ship's bow would settle deeper in the water, and water would spill from one compartment to the next in sequence, rather like water spilling across the top of an ice cube tray. This is what happened to "Titanic", which had suffered damage to the forepeak tank, the three forward holds and No. 6 boiler room, a total of five compartments. "Titanic" was only designed to float with any two compartments flooded, but she could remain afloat with certain combinations of three or even four compartments—the first four—open to the ocean. With five compartments, the tops of the bulkheads would be submerged and the ship would continue to flood.