Marooned: Stinger, Book 2 — E.T. Watson

Jim Kelly was shot up in Viet Nam and was being sent back to the states by plane when it developed trouble and crashed into the ocean many miles off course. Everyone but him got into rafts on the left side of the aircraft. Jim got out on the right side into a raft, then drifted for weeks hundreds of miles below the shipping lanes. Jim ended up on a huge island, and if you would like more info read the book.