The knowledgable Greek scientist Archimedes determined that if an object weighs less than the water it displaces it won’t sink. Did you know that concrete, too, can float in water?
In fact, during World War II, the United States made two dozen concrete ships to conserve steel. Students from universities around the country are currently competing with one another to design the best concrete boat.
With a few simple materials and an hour of time, you too can engineer your own concrete ship.
As described in Popular Science, you will need the following materails and to follow these steps to build a concrete boat:
- 10-lb. bag Portland type 1 cement
- 20-lb. bag sand
- half gallon water
- Large sturdy container
- Two feet of 3-inch-wide-by-1.65-inch-thick polystyrene foam insulation
- Polyurethane glue
- Plastic wrap
- One 3-foot-long-by-5-inch-wide sheet of ?-inch-thick plywood
- Nonstick silicone spray
Follow these five easy steps to become a captain of your own concrete ship:
Lay the polystyrene foam on a flat surface. Draw an oblong egg shape on the foam.
Cut the shape out of the foam with a utility knife. Then round off one side of the foam. Sand until smooth.
Encase the mold with two layers of wrap. Shrink the plastic using a blow-dryer.
Saw the plywood to fit the mold. Next, smear polyurethane glue on the sculpted foam’s flat side and put it facedown on the plywood. Press until dry, about two minutes. Coat exposed plywood with silicone spray.
Mix the cement and sand in the wheelbarrow. Stir well, add the water, and mix until uniform. Slowly pour the concrete over the mold. Let it dry for 21 days, and then sand until smooth.
Set the boat and water and watch concrete science in action! Want it to glean and shine? Remember to polish the floors and deck of your newly constructed concrete boat!
For extra boyancy, consider using lightweight aggreate material in your concrete, such as foam, beads, and expended glass shale.? The shape of the concrete boat matters too, as a different amount of water will be displaced.