My personality would have me helping people onto boats and trying to keep everyone calm. At some point, when all the boats are loaded, and there are more people than spaces and nothing around to be fashioned into a life raft, then things become interesting. When coming face to face with the fact that within 30 minutes of jumping into that water, possibly sooner, I will be dead, I wonder what I really would do.
I teach wilderness survival techniques to young people and occassionally situations come up in the news that we talk about. Recently a guy amputated his lower arm to release himself from a boulder that had him pinned for a couple of days. That decision seems easy compared to giving up the last seat in the last life boat.