In the book, The Voyage of the Frog, I think the theme is face your problems. I say this because when David's uncle died David was sobbing constantly, but it didn't stop him from completing what his Uncle wanted. David's uncle wanted David to spread his ashes into the sea. David could  have been sobbing everyday instead of taking that mission from his uncle. The passing of Uncle Owen didn't influence David to give up and let his feelings knock him down. David took the mission and spread his uncle's ashes into the sea. Another example, is when David was lost three hundreds miles out into sea he didn't let that knock him down. He got up and faced his problem. David prepared a plan to drink only four cups of water each day and preserve food. David also faced some wildlife when he was out to sea. David encountered with a shark and a pod of killer whales. David didn't freak out and stopped sailing he moved on and ignored the animals. David was starving for days sleeping in a soggy bed that was very uncomfortable. Those are tough things to deal with since you are out at sea alone with no sign of civilization. David faced his problem and used what ever he had with him. David didn't give up on getting his ticket home. He took the hit and solved his problem. Now he got back home while also completing to spread his uncle's ashes. The theme if the book is to face you problem because David faced his problem when his uncle died and when he was stranded in the middle of the sea.