hi MGY i help you here

titanic can stay alfot with any two comaprtmenst floded and cary on sailing she can saty afloat with any four but she ant move too much weight. She can't stay afloat with five comaprtments flodded the weight ration is too much and as a compartment fills it drags the bow down deeper causing water to spill other the bulkheads into boiler room bulkhead number six and because the engine rrom is a massive whole for a few decks this fills rather rapid casuing the events to get quicker.

as the head gets lower the presure on the structuire gets worst and this is when rivets begine to fail. bulkheads end up giveing way to the huge pressure and then she starts to sink faster and faster and faster and then she will go.

the titanic by rights shouldnt have snapped in half but this was beacuse of a design floor. called the expansion joint between funnel number 3 and four which on the britannic the titanic's sister ship she is a whloe ship her expansion joint was changed right at the start after the titanic incident as harland and wolff relized they weas something wrong with the expansion joint as it was crudly built and had a major design floor.

the cunard pari didnt have expansion joint. I still dont kno wwhy the olympic class liners had such an old system as you dont see expansion joints on any new ship's. The titanic had many design floors for one they didnt cap the top of the bulkheads to make them completly water tight meaning once the water get to a certain point it is able to flow over into the next bulkhead and major floor in the design.

i hope i have been a masive help on this topic thank you