There have been quite a number of books about boaters surviving for extended periods at sea - in boats disabled and adrift, in capsized boats and in life rafts.

Check the boat section in the sports area in your local bookstore. They are a fascinating read and quite an education in resourcefulness.

Oddly enough, the biggest problem with being adrift in the ocean is - a lack of water!!! Drinkable water, that is. From the accounts I've read, survivors had to develop a taste for sushi and dried fish.