Introduction

Boats come in all sizes, shapes, and colors!

And, some have trouble going the same direction as others!

Have you ever wondered how a large supertanker filled with oil can float?

Objects submerged in a fluid such as water appear to weigh less than they do when they are not in the water. The liquid exerts a buoyant force on the object.

Archimedes is credited with discovering that the buoyant force on an object is equal to the weight of the displaced fluid. He is said to have discovered this principle in his bath while trying to think of a way to determine whether the king's new crown was gold or a fake. Legend says that he ran naked through the streets shouting, "Eureka."

Archimedes Principle also applies to floating objects. An object floats on a liquid if its density is less than that of the fluid. For our supertanker to float it must displace a volume of water equal to its weight.

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Objective:

• To build a boat out of cardboard and tape capable of holding two people that can be launched and paddled across a pool.
• To apply Archimedes' Principle to your design.

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Materials:

1. Only cardboard and tape may be used to construct the boat.
2. Only corrugated cardboard will be allowed. The maximum allowable thickness of corrugated cardboard is one-half inch.
3. You may NOT use any other objects to contribute to the structural rigidity or the craft's flotation ability.
4. You may only use clear, cheap postal tape that is two inches wide. No reinforced fiber packaging tape or duct tape will be allowed. Examples of the tape will be shown in class. NO GLUE!

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Design Parameters:

Boats will be subject to a technical inspection before the day of the race and must follow these guidelines. Any boat not following these guidelines will be disqualified.

1. Boats must be made from corrugated cardboard. The entire hull, superstructure, and seating must also be made from corrugated cardboard. The maximum thickness of cardboard allowed is two thicknesses (this does not count the where the "seats" contact the boat structure). The maximum single thickness of carboard you may use is 1/2 inch. Thus, the maximum thickness of your two thicknesses of cardboard is one inch. The "seats" may be made of boxes or cardboard. They must comply with the thickness guidelines. You may not use layers of one-quarter inch cardboard to meet the one-inch maximum requirement. Again, the maximum thickness of one piece of cardboard is one-half inch and you may use two thicknesses of this cardboard.
2. No treated cardboard is allowed. Your cardboard must be brown! Treated cardboard looks like it has been waxed. You may not use painted cardboard. Again, your cardboard must be brown! Please note: you may paint your boat with water-soluble paint as part of your decorations for your theme. You may not entirely paint all your sides. Paint is only for decoration -- it cannot make your boat water-soluble.
3. Tape may only be used for its adhesive properties. You may not use tape as if it were twine.
4. NO rafts are allowed!
5. The maximum length is 7 feet. Your boat must be wide enough to fit through the doorway.
6. The hull may not be wrapped in plastic, duct tape, shrink wrap, or anything else. Only the seams and joints may be taped, not the entire boat. In other words, you may only tape where you put two pieces of cardboard together. When taping seams, only 1.5 inches of tape can overlap the seam. When taping seams, a minimum of twelve inches of untaped cardboard must separate seams.
7. You may not use reinforcing structures between your two layers of cardboard. That violates the two thickness' rule.
8. Your two thicknesses of cardboard must physically touch. They may not be separated by air. Your boat design must provide your buoyancy; buoyancy provided by enclosed air is not allowed. In other words -- no boxes taped together.
9. You may use cross bars that are incorporated into your seats to stabilize your boat. Since these are part of your seats and you may only have two seats, you can only have two cross bars. You may have no more than one cross bar to stabilize the front of your boat.
10. Swimming on a cardboard surfboard is not allowed. No appendages are allowed in the water.
11. The passengers of your boat may not be enclosed above the shoulders of the occupants. Both people must be visible while the boat is in the water.
12. Boats must be free of sharp edges, objects with pointed edges, or any other menace.
13. All occupants of a boat must be good swimmers. A WSI instructor will be present.
14. All boats may be propelled through the water by:
    • utilizing the paddle that is provided by the instructor
    • constructing a device that will power the vessel, such as a paddle wheel.
    • using a sail
    • any combination of a, b, or c.
15. No arms or legs may be in the water to assist with stability or propulsion.
16. To qualify as a finisher, both teammates must be in the boat at the end of the race.
17. Extra credit will be awarded for a theme. It will be added to the group daily grade.
    • A theme can consist of coordinating clothes, hats, etc.
    • A theme can consist of decorations on your boat. All decorations must be made of cardboard and be affixed to the boat with approved tape. You may also decorate your boat with markers Ino paint, etc.) in addition to affixing cardboard decorations.
    • The content of the theme must be appropriate, following the rules described in the student handbook.

You will work in 4 member student teams. This will be a four-week assignment. Our study of fluids coincides with the boat challenge.

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Grading Guidelines:

1. There will be a group grade for your boat. This group grade will count as one daily grade. Both teammates must be in the boat.
• Any boat that even makes it off the starting line will earn 80 points.
• Any boat that successfully negotiates one-quarter of the pool's length will receive 85 points.
• Any boat that successfully negotiates one-half of the pool's length will receive 90 points.
• Any boat that successfully negotiates three-quarters of the pool's length will receive 95 points.
• Any boat that successfully negotiates the entire length of the pool will receive 100 points.
2. The race will be timed. Winning times and pictures will be posted on the Internet.
3. There will be an individual grade awarded for your summary of the project. This will count as one daily grade. You may submit your answers using the form below (remember--if using the form, your daily assignment for the individual grade is due one day earlier). It must include the following:

• A one paragraph description of how you would change your design. In other words, what part of your design was effective? What part of your design did not work? How would you change it? 25 pts
• Describe three things that you saw other students do that you consider being very effective. 25 pts
• Archimedes Principle states that "The buoyant force on a body immersed in a fluid is equal to the weight of the fluid displaced by that object." An object floats when its weight is equal to the buoyant force. Write a one-paragraph description of how this principle applies to the floatation of your boat. 25 pts
• Describe how you would calculate the buoyant force exerted on your boat by the water. What measurements would you take and how would you interpret them? 25 pts

Daily Grade Assignment Form

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Extension of Activity for AP Physics:

AP students will construct their boats out of plastic, tape and twine according to the following information.

Plastic Boat Challenge Information

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Record Board

These times are for a shoreline start. In other words, students did not put their boats into the water until the whistle was blown and time began.

Rank	Team Members	Time in seconds	Year Set	Teacher
1	Andy O., Doug Z., Lane M., Tom W.	21.00	2000	PES
2	RS, JE, ML, KS	22.60	2000	JRB
3	Taylor D., Kim H., Jennifer D., Andrew H.	25.67	1999	PES
4	David W., Katie H., Hillary S., Tim B.	26.21	1999	PES
5	Ashley W., Niki W., Alyssa C., Kevin R.	27.00	2000	PES
6	MN, CP, PE, MW	27.00	2000	RLS
7	GS, BH, EC, WB	27.05	2001	RLS
8	CS, JR,JS, DD	28.57	1999	JRB
9	Loralei H., Donya W., Malik H., Derek F.	28.64	2001	PES
10	NN, JR, WR	29.00	2000	JRB

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Suggestions for Conducting the Regatta

Suggestions

Student Pictures

Pictures of Boat Activity

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1998 Student Reactions

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