Gary Paulsen The Voyage of the Frog

David thought he was alone, that the ocean around him was all there was of the world. The wind screamed, the waves towered, and his boat, the Frog, filled ever deeper with the sea water.
His uncle Owen would be so angry at what had happened. It was Owen who had taught him about sailing safely, Owen whose final voyage this was to be. Only days ago, Owen had died in hospital, his last wish for the Frog that David take her as his own, sail her beyond sight of land and, once there, scatter Owen's ashes.

Fourteen year old David journeys out to sea to scatter his dead uncle's ashes. A terrible storm leads him off course, and with little fresh water and food and many injuries, he learns skills of survival.