How to Build a Submarine From a Water Bottle

Make a replica of a working submarine with a water bottle.

Submerge any thoughts you may have about the impossibility of building a toy submarine. This project is good for young children who can learn the basic theories of buoyancy by constructing a submarine out of simple objects found around the house. Combine bath time with a science lesson and talk about how blowing air into the submarine straw makes the water inside the submarine less dense than the surrounding water, and causes the sub to rise.

Things You'll Need

• Empty 16 oz. plastic water bottle with cap
• Hammer
• Block of wood
• Nail
• Scissors
• Flexible straw
• Putty
• Masking tape
• 7 quarters
• 2 rubber bands
• Bathtub

Instructions

1. Place the water bottle camp on a block of wood. Hammer a nail through the top of the water bottle cap to make a hole for the straw.

2. Cut two small holes in the plastic along one side of the water bottle. Position the holes so they are 2 inches apart and in line with each other lengthwise.

3. Tape three quarters together. Tape the remaining four quarters together.

4. Stretch the rubber band around the bottle to attach the taped group of four quarters directly below the hole nearest the bottle bottom.

5. Stretch the other rubber band around the bottle to attach the taped group of three quarters directly below the other hole.

6. Place the end of the straw near the flexible section in the top of the bottle cap. Pack the putty around the straw to seal it and screw the cap on the bottle.

7. Fill the bathtub with water and submerge the water bottle. Let the “submarine” fill up with the water and sink, keeping the straw above the water.

8. Blow into the straw and watch the “submarine” rise.

References

• Science and Technology Focus - Blow the Ballast!

Resources

• Read this Article in Spanish