What importance does the life raft serve in Summer of My German Soldier?

In the story, Ruth is characterized as Patty's life raft. To Patty, Ruth (the family housekeeper) represents love, loyalty, and courage. She is the one constant in Patty's life.
Ruth is also the only one who visits Patty at the reform school. In discussing her parents, Patty is devastated when she discovers that her mother is indifferent to her fate. She begs Ruth to tell her what is wrong with her and why she is always getting into trouble. Ruth carefully explains that there's nothing wrong with Patty, and she reassures her that she loves her the way she is.
Ruth tells Patty the truth: that her parents aren't exactly the best parents around. They will always be what Ruth calls "irregular seconds," and she advises Patty to stop hoping that she will receive acceptance and love from them. Eventually, Ruth's visiting hours are up, and she has to leave. In watching her go, Patty imagines that her own "life raft" is "floating away towards the sea."
However, Patty experiences an epiphany as she watches her beloved friend and mentor leave. She thinks that she can see "land" in the distance and finally realizes what life rafts are really for: "taking the shipwrecked, not exactly to the land, but only in view of land. The final mile being theirs alone to swim." Patty comes to appreciate the role of a human "life raft" like Ruth.
In encouraging Patty to finish high school and to go on to college, Ruth has outlined for Patty a way out of her dismal situation. However, Ruth's encouragement and support can only go so far; it will be up to Patty to steer her own path and to work for her own success and eventual freedom. In this, the importance of a life raft cannot be underestimated: Ruth's support will enable Patty to see the possibilities in her life and to succeed in her attempts to break free.