Q&A for How to Build a Cardboard Boat

It definitely can if you make your boat big enough! A box that's 1 by 1 by 3 ft (0.30 by 0.30 by 0.91 m) can fit a 187 lb (85 kg) person without sinking, so you should have no trouble building a boat that supports at least 240 lb (109 kg).

That depends on the size of the boat! The key is making the boat large enough to support a certain amount of weight without taking on water. Just multiply the height, width, and length of your proposed boat to get the volume—then, multiply this number by 62.4 to see the combined amount of weight it can support in the water.

Definitely! Lots of community regattas are held at public pools and lakes. Just be sure to apply varnish to your boat so it doesn't get soggy when it hits the water.

Yes. Make sure to add a couple layers of cardboard so it doesn’t sink. Remember, cardboard isn’t the best material to make boats out of, but you can.

Yes, if it is big enough, unless you plan on setting sail in actual water. Even a cardboard boat would not work for use in real water. But, in the future, if your parents tell you not to do something, you probably shouldn't do it.

Yes, if it can hold a passenger, then it can definitely hold 6 rocks! You can test it beforehand with a scrap model if you are still not sure.

Probably, but depending on the weight of the person, you might need to add more pool noodles.

The boat should be big enough to hold your crew. So, depending on how tall your crew members are, then that's how big your boat should be but also remember about reinforcing your boat and the weight of the boat so it won't sink!

It might be able to handle miniature "rapids" in a small creek or pond but if you put it on real rapids, you'd likely not see it again.