Content

Boat building challenge

Use aluminum foil to make boats and then test designs by seeing how many pennies or paperclips they can hold.

Please find a printable PDF of this activity here.

Background

• When an object is in the water, gravity pulls the object down and displaces some of the water, which means some of the water is pushed aside.
• Gravity pulls the displaced water down, and causes an upward force on the object, called buoyancy.
• The amount of water displaced depends upon the volume of the object. A higher volume causes more fluid to be displaced, which means more buoyancy.
• Boat designers have to consider buoyancy as well as friction when deciding on the shape of a boat’s hull. A boat designed for speed must have enough displacement to stay afloat, but surface area has to be minimized to decrease the effects of friction.
• On the other hand, an object designed to carry a heavy weight, such as a cargo ship, must be designed with greater displacement.

Materials

• Sheets of aluminum foil (30 x 30 cm)
• Tub of water
• Pennies or paper clips

Instructions

• Design and build a boat with one sheet of foil.
• Float boat in the tub of water.
• Add pennies or paper clips one at a time into the boat.
• Design a new boat to hold more weight!

Extensions

• Calculate the boat hull’s surface area and compare/graph to the number of pennies held.
• Design and build sail boats and use a fan for wind.
• Participate in the Sea Perch Challengeoffsite link.