I just answered this question for someone else but i figured more people would want to know the answer.
okay, it is kinda tricky to get on the boat, it keeps giving you the option to examine right? yeah, well, you have to hit just the right spot on your screen to get it to say use canoe. the screen is at a strange level of view and its hard to hit the arrow and it keeps thinking your hitting the boat. thats why its saying examine. keep trying, you can use the boat as soon as your done making it. don't get frustrated, just keep tapping the screen around the arrow until USE CANOE pops up.