Sailing can be a blast, but when you add to the water a boat made of cardboard boxes, you can explode with the fun you'll have. This can be easy, but make sure you have all of the materials on hand before you begin and know the size and weight of your crew. With (optional) proper support to your cardboard box with extra corrugated cardboard and waterproofing with plastic, this piece of handiwork can really float!
Draw your design on paper first. This will reduce problems down the line. Optional: Make a small mock-up if you need to, out of smaller pieces of cardboard.
Translate the size of the mock-up or drawing to actual size by setting it on graph paper. (Example: Each square could equal 1 inch or 1 foot.)
Cut and bend the cardboard to fit your design. (Example: Cut 1-by-1-by-3 inch 'pieces from the cardboard box for proper assembly.) Optional, yet highly suggested: You may draw your design onto the flattened cardboard box so you know precisely where to cut or bend. Use the dimensions from your graph paper by measuring with a ruler or tape and marking it on the cardboard.
Wood-glue the pieces together to finish the assembly. Use clips or clamps to hold the different sections together as they dry. Optional: Reinforce areas if needed, with corrugated cardboard. This optional step will reinforce the cardboard box and make it even sturdier.
Paint and decorate your boat, though this is optional.
Cover the bottom and sides of the boat with plastic sheets prior to launch. Duct tape these sheets to the cardboard box boat, making sure the tape is on the inside of the boat. This step will make your boat waterproof.
Boats more than 10 feet long steer the best. 18 inches or higher allows people to sit and paddle in the boat. 30 inches wide is good for one paddler, and 48 inches fits two. Proper bending can be obtained by slightly creasing the cardboard with the dull side of a knife and using a straight edge.
Plan the correct size of your boat: 1 by 1 by 3 feet will be able to keep 81.6 Kilogram afloat. Bends and folds in the cardboard weaken the boat.