Boat w Rubber Band Propeller
I saw a similar wooden boat in London Maritime Museum souvenir shop. The design looked simple and doable to me so I tried and here it is. Kids are very happy with it. The hole in the front can be used to plug a flag, though i yet to make one.
Refer the picture of my printed boat for assembly, i guess it's quite easy to assemble. You need a rubber band to power the boat.