For anyone who wanted a simulator to simulate sinking, this 2D sinking simulator recently met its crowdfunding goal: http://www.indiegogo.com/projects/sinking-simulator
A sandbox demo is already available, while an improved, deeper version is in the works. From what I've done with it and seen done with it, it has been done well so far! The Titanic model is haphazard, but it still does a nice job, and small touches to improve its accuracy only make the simulation more closely match the latest sinking theories.