How to Make a Cardboard Boat

Making a cardboard boat is an interesting experiment in physics, particularly the concepts of displacement and water pressure. Your boat will float if it displaces enough water, and water pressure will help to keep the protective garbage-bag waterproofing layer you're going to apply to the outside of the boat in place. This project is also a great afternoon craft challenge for groups of any ages: Let everyone make and decorate a boat, then have a competition to see which boat is faster, holds the most weight or floats the longest.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Large cardboard boxes Duct tape Sharp scissors Garbage bags

1. Collapse several cardboard boxes by separating the top and bottom flaps, then folding the entire box flat. Slit open one side of each box so that you can lay the entire piece of cardboard out flat.

2. Tape four spread-out boxes of the same size, one on top of the other, together in the middle of each side to make the bottom of the boat.

3. Cut two sides and the top out of four cardboard boxes of similar size. These will be the corners of your boat. Slide them between the layers of the boat bottom, at its corners, and tape them securely into place.

4. Tuck flat pieces of cardboard in between the upright pieces of the corners so that they form side walls for the boat, then tape them firmly into place. Tuck part of the side wall between the corner pieces and the boat base if possible before taping.

5. Reinforce the corners of your boat, both inside and out, with folded pieces of cardboard or cut-out box corners. The idea is that there shouldn't be any seams directly in the corners, and the wall pieces should be taped together into one continuous unit.

6. Fold pieces of cardboard over the edges of your boat sides, taping them in place. Add more folded cardboard in the corners again. Check to make sure that the walls are sturdy and will hardly bow in.

7. Waterproof your boat by duct taping layers of garbage bags around the outside bottom and sides. Overlap the garbage bags so that there is no exposed cardboard, and use liberal amounts of duct tape.