Boat Engineering
In this activity, we will explore the physics of sinking and floating. Through comparing and contrasting two boat designs, early and elementary scientists can practice simple math, science, and engineering skills.
Learning Objectives
Watch this quick video tutorial!
Science Content Knowledge: Learning about the Engineering Design Cycle and the physics behind sinking and floating
Science Process Skills: observing, measuring, comparing, experimenting
Developmental Skills: fine motor skills
Materials
Tub/basin
Water
Aluminum foil
Stones, pebbles, or any uniform weights
Towel
Slotted spoon
Models of boats like toy boats or objects that float like boats (e.g. soap dish, custard cup)
Set-Up
Choose a water-friendly location!
Fill tub/basin with water
Cut aluminum foil into 6-inch squares
Activity Instructions
Step 1: Plan (Investigate Materials)
Becoming familiar with materials and properties of an object is an important part of planning! Begin by observing models of boats and discussing their characteristics and then testing the aluminum foil to see what it can do. Consider the following questions when exploring the materials:
What SHAPE is the boat? Compare the boats and identify if they are pointy, flat, round, square etc.
What are boats used for? A boat is designed to carry people or cargo.
What do you see on the boats that help them keep water out? It’s important to keep water out of the boat so it will stay afloat.
Does the aluminum foil float? Place the flat square in the water to test it out!
How does the aluminum foil feel? Is it stiff or bendy? Try folding it into a new shape.
Make a plan! What changes do you want to make to your aluminum foil to make a boat that floats?
Step 2: Build
It’s time to put your plan into action! Design two boats, one with a canoe-like shape and one with a raft-like shape. Explore the following design questions:
What shape is it?
How many sides does it have?
Is it long or short?
How big is the inside?
Step 3: Predict
Make a prediction. Will both boats sink? Will they float? Which one do you think will hold more weight? Record your predictions on your Cargo Carry Worksheet.
Step 4: Test
Test one boat at a time. Place your boat design on top of the water. What happens? If your boat is floating, try adding some weight!
Slowly, add one weight at a time being sure to distribute the weight evenly throughout the body of the boat (i.e. do not pile them all in the middle). Count how many weights the boat can hold before capsizing (sinking). Record how many weights your first boat design held on your Cargo Carry Worksheet.
If your boat sank, rescue it and try again!
Now, try your second boat.
Place your boat design on top of the water. What happens?
If your boat is floating, try adding some weight!
Slowly, add one weight at a time being sure to distribute the weight evenly throughout the body of the boat (i.e. do not pile them all in the middle). Count how many weights the boat can hold before capsizing (sinking). Record how many weights your first boat design held on your Cargo Carry Worksheet.
If your boat sank, rescue it and try again!
Step 5: Improve/Try Again!
Examine your boats. What parts of the boats do you think helped it to float? Was it the length, the shape, the amount of space in the middle?
Choose 1 part of each boat to change. It is important to only change 1 thing, so that you know if the boat does holds more or less weight, it is because of the thing you changed.
For example, if we decided to change the amount of flat space in the middle of the boat, we could either curve the sides more to reduce the amount of flat space or press the sides down to increase the amount of flat space.
Once we have decided what to change and made the change to our boats, we can test them.
One at a time, place a boat into the tub. Slowly, add one weight at a time being sure to distribute the weight evenly throughout the body of the boat (i.e. do not pile them all in the middle). Count how many weights the boat can hold before capsizing (sinking). Record how many weights your second boat held on your Cargo Carry Worksheet. Repeat with the second boat.
Continue to design, test, and incrementally re-design for five trials or until your boat can successfully hold twice the weight it held in the original design!
Science Background
To successfully build a boat that not only floats, but can also carry weight, depends on the boat’s size, material, weight, and shape.
In this experiment, we learned that the shape of an object affects how buoyant it can be. While the boats were made of the same material (tin foil) and were approximately the same shape, the boats were able to carry very different amounts of weight just because of their shape.
One possible reason is due to weight distribution. If a boat is narrow, there is less space to distribute weight which might mean parts of it get heavy faster. Another reason might be the amount of space a boat takes up. A small boat displaces just a little bit of water where a large, flat boat might displace a lot of water changing how buoyant it is.
We used the design cycle to increase our boat’s carrying capacity. Small changes can have a big impact, but it's important to only change one thing at a time. This is called experimental control and allows us to make conclusions about what effects our changes had on our design. Including these simple elements of the scientific process can help children develop strong science reasoning skills at an early age!