I literally can’t stand the thought of just throwing boxes away, no matter how big they are, though the bigger the box, the harder it is.
I cut the box in half lengthwise. Along the flaps, I cut a few inches further in and pulled the flaps together. I then held the flaps in the shape I wanted the point of the boat to be and traced it. I then cut off the excess cardboard. With just enough packing tape, I taped the ends of the boat in place, and taped both halves of the boat together. Naturally we had to have fish, complete with a fishing rod. Sadly the velcro wasn’t strong enough for K to catch his fish. I’m still working on a better solution. Add some water… and sail away!