Introduction: How to Build a Cardboard and Duct Tape Boat

Building boats are fun, but can be time consuming. If the boat is built for as a two seater, then the time spent making it will take longer. Remember to make measurements of the boat before starting. Do not eyeball it, as it usually does not work out. Having fun with this project is key to success! Average time for building a cardboard and duct tape boat is about 10 hours, but our boat took about 16 hours, 8 rolls of duct tape (regular duct tape and gorilla tape (stronger)). Regular duct tape is enough to stop water from entering, but to be extra safe, gorilla tape won't hurt, except it might burn a hole in your wallet....

Follow the rest of steps to ensure a well built cardboard and duct tape boat!

Step 1: How to Build the Cardboard Boat

Our team's boat consisted of layers of cardboard boxes. We used bike boxes as they are usually stronger than regular cardboard. When starting off, keep in mind how many people will be riding in the boat as the layers of cardboard needed needs to be accounted for. Next, measure out the dimensions, and make sure that there is enough leg room, length, width, and height.

The bottom of our boat was composed of 3 layers of bike cardboard, with 2 layers for the sides as well as for the back. The slanting front side was composed of 1 layer because there is no weight being put on it so it doesn't need to be that thick. At this point, you should have measured out the desired pieces, and have it all ready to be taped together. Remember, only duct tape is allowed. When the tape is added to the boat, it will weigh a lot more, but do not be afraid because the weight doesn't matter too much at this point. Our boat weighed 25 pounds in the end, and it not only floated but it held up to 360 pounds too!

Step 2: How to "waterproof" the Boat

After you have the boat assembled. it's time to add the duct tape. This is what "waterproofs" the boat. Regular duct tape is fine, but gorilla tape can be used too if you want the boat to be even stronger. But it will cost a lot more than regular tape, so if you're willing to spend the extra bucks, then go for it.

To start off, tape the bottom side of the boat first, and make sure to tape both sides so that the water cannot get in from the bottom and it won't let water seep into the card board from the top if water was to splash into the insides. Do the same to the sides of the boat as well as to the front and back. But for these sides, it is not needed to tape the insides. Once you have taped those sides, start putting the boat together. Tape the corners and attach the pieces.

Once you have finished taping it together, make sure to go over it again to make sure that there are no holes or air bubbles where water can get in. After it is done, the boat will be pretty heavy, but as mentioned before, it is not something to worry about.

Step 3: How to Create the Costumes and Props

After the boat is done, it is time to consider making the costumes. For this particular boat project, our team decided on the theme from the movie "Castaway". So we decided to put fedex boxes on the front of the boat, and for the costumes, we each painted a design onto white t-shirts. So in the end, one shirt had "fedex" on it, and the other had the face of wilson which is the face painted onto the volleyball in the movie. Finally, we added a simple cardboard piece onto the side of the boat that said "Castaway".

For the design on the shirt, I cut out a outline on cardboard first so that I could just color inside of the template, thus making it look neater and more exact. We also bought a Wilson volleyball that had the face on it, for about $20 at sports authority, but the stores that have this may vary.

Step 4: How to Find the Density and Waterline of the Boat

After all has been done, it is time to find the density of the boat in order to see if the boat will float or not. The density of water is 1 g/m3 or 1000 kg / m3, so anything below it will float.

For example:

-Boat weight: 25lbs

-Mass of riders: 335lbs

-Total mass: 360lbs

-Total volume of boat: 0.4m3

Density = Mass / Volume

360lbs to kg = 163kg

Density = 163kg / 0.4 m3


divide by 1000

= 0.4 as the density.

Since it is below 1, the boat will be able to float carrying a mass of up to 360lbs.

The waterline will be about half way on the boat, which is nothing to worry about

After all this is done, you are ready to get the boat on the water and float it! Have fun, and enjoy!