Build and test a cardboard boat
Why do some things float and others don’t? Learn about a predictor for buoyancy, and how to size and build a boat out of cardboard. Want to have some fun? Build a surfboat! Or, build something smaller that you can test in your bathtub. Your creativity is the limit!
Think like an engineer / buoyancy experiment
This experiment complements the buoyancy / build a cardboard boat project from my second book, The Cardboard Boat Race.
The videos immediately below give an introduction to a simple problem-solving process. We have 3 hypotheses or “guesses” about a predictor for why some things float and others don’t, then conduct simple experiments to test each hypothesis in turn.
Once we can predict whether something will sink or float, we can use that knowledge – in the form of a simple math recipe – to design or size a boat. That’s the next challenge!
I did these experiments for middle grade kids at Blanchester Intermediate on March 4, 2021. It was so amazing, that I duplicated the experiment at home and shot video. So… this is not quite as good as live, but it’ll give you an idea of the overall content and flow.
Keep scrolling down for cardboard boat building tips and videos!
The Buoyancy Project
Want to check out the book the expands on the project & adventure? Check out the Buoyancy Project: Putney Hicks Inventor Adventures–Book 2!
2023 Firebird Book Awards–WINNER!
A perplexing task. A mystery to solve. Can a scientist-in-the-making find the answers hiding in plain sight?
Putney Hicks is itching to take on her next challenge. Preparing for her school’s cardboard-boat regatta, the twelve-year-old inventor hunts down ways to stop the flimsy craft from sinking into a soggy mess. But after she rescues her neighbor’s dog from a rip current, the curious girl can’t shake the thought that the solution is right in front of her eyes…
Joined by her new canine companion and using her magical tablet as she explores an alligator-infested lagoon, Putney is dismayed when she’s paired on the project with her arch-nemesis. And as they reluctantly put their heads together, she suddenly realizes that the scaly swamp predators could hold the secret to their experiment’s success.
Can these stubborn rivals overcome their differences and construct a winning waterproof design?
The Buoyancy Project is the ingenious second book in the Putney Hicks Inventor Adventures middle-grade series. If you like scientifically empowered young women, entertaining escapades, and real-life mathematical motivation, then you’ll love Marsha Tuft’s MacGyver-like enterprise.
Buy The Buoyancy Project to sail full STEM ahead today!
What's the fun all about?
Here’s a short video showing a simple cardboard truss raft and a similar (slightly refined) surfboat with foam insulation platform covered in marine grade fabric shell… for easy carrying to the beach, or a pool on raft night!
My great-nephews had a blast!
Teaser video - 3:35
Making cardboard tube trusses - 14:31
stand test - cardboard trusses - 0:37
build and test a cardboard boat
Why do some things float and others don’t? Learn about a predictor for buoyancy, and how to size and build a boat out of cardboard. Want to have some fun? Build a surfboat! Or, build something smaller that you can test in your bathtub. Your creativity is the limit!
Materials needed:
- Cardboard… how much depends on how big you want to build your boat, and what you want it to be able to hold.
- A measuring tape
- A calculator (or access to a computer… sample spreadsheet provided)
- Duct tape
- A plastic tablecloth (or 2 or 3, depending on how large you go with your boat)
- Something to cut your cardboard with
- Someplace to test your boat… like a bathtub, pool, or lake.
- OPTIONAL: some weight, to verify that your design works. Which means, you’ll also need to be able to weigh your boat with the extra weight. (You can always do this by standing on a scale holding your boat and the weight, then subtracting the weight of you alone.)
I’ll be chatting live on the Girl Scouts of Western Ohio Summer Camp 2020 Facebook Page Friday, July 17, 2020 at 1 pm and 3 pm EDT to answer your questions.
Download the experiment PDF below! Check out the Excel spreadsheet to size your boat quickly!
Experiment video - 32:00
All photos by MK Tufft with the exception of the following two images from the “Why do some things Float? Others Don’t?” poster (above):
- Cruise ship image by Limbovision from Pixabay
- Submarine image from https://www.navy.mil/management/photodb/photos/030814-N-0000X-003.jpg . ”The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement.”
buoyancy
Why do some things FLOAT, and others DON’T?
Can we PREDICT this?
- Is it WEIGHT?
- Is it SIZE?
- Is it DENSITY? (Weight / Volume)
Does MATERIAL matter? (Waterproofing?)
If you need a refresher on buoyancy… or why some things float and others don’t, check out the experiments below for a couple refresher options.
I’ve got an updated Buoyancy Experiment and PDF coming soon, using some of the posters from my upcoming book, Putney and the Magic eyePad–Book 2: The Cardboard Boat Race.
Meanwhile, here’s the experiment we used in Girl Scouts Year of the Girl STEM Summer Camp in 2018 and 2019. I bought some special materials for this project… some lock-up cups and wood pen blocks which you probably won’t have. Don’t worry! You can do all the important bits without them.
More pics
