Just as Hanks is inflating the raft, the stow bag gets caught on something and then the line breaks and he floats to the surface. I assume the raft stow bag had a survival kit in it and that is why the writers had to figure out a way for him to lose it.

One of the points the writers of the script were trying to make is that man, with little or no tools or training to survive, can adapt and learn from his mistakes and live to tell his story. Hanks' character evolves physically as well as emotionally. The most telling scene for this is when he sees the port-potty door and within seconds, sees the true potential of this otherwise piece of trash.

He also undergoes a form a spiritual transformation, a willingness to release himself from his former, controlling-self, to a more free thinking- willing to throw himself to the winds of fate and see if they take him off his island. He is no longer bent on constructing his future from a preconceived notion with an attached time table, but rather live his life in a principle/ spiritual ideal driven manner.

Are our PSK's an attempt to control our lives to the smallest detail, even the times of our lives that we don't plan on happening, but we want to control in the event they do? Or are they a simple manifestation of our drive to survive and have a future to live? Or somewhere in the middle?