What is the best design for a boat made of only cardboard and duct
tape?  The boat must hold three people, and be very inexpensive. 
Multiple designs would be accepted if you can't determine which one
would be best.  The boat must be capable of being paddled around a
pond, with several potential dunkings.

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Clarification of Question by caecias-ga on 28 May 2003 10:05 PDT

I need an answer by this friday, May 30.

Here's a page with pictures of last years winners:
http://www.suu.edu/sast/tech/2002boats.html

Greetings, caecias!

Since the purpose of the competition is to get students to understand
design concepts well enough to construct a seaworthy boat, I am sure
that you will want to design it yourself with your teammates.

Here are some sources for ideas:

http://www.css.cornell.edu/de21/cardboard
http://www.cmesa.org/advisor%20page/cardboard/cardboard_boat.htm
http://www.nsd.nf.ca/boat1s.html
http://www.skillsalberta.com/cardboardpics.htm
http://jflis.com/leisure/canoeing/boat_2001/boats.htm
http://jflis.com/leisure/canoeing/boat_2000/cardboard2000.htm
http://www.dailyegyptian.com/btc98/B/regatta.html
http://www.dailyegyptian.com/spring96/042996/regatta.html


From the US Department of Energy, here's some helpful advice about
building your boat:
http://newton.dep.anl.gov/askasci/chem99/chem99601.htm

And some helpful tips from Jimmy Good Toad:
http://www.knowledgehound.com/topics/boating.htm#cardboard

And some helpful tips from the Great Cardboard Boat Regatta:
http://www.gcbr.com/tips.html

Good Luck,

aceresearcher

Watertightness 

Boats must also be watertight?that is, invulnerable to leakage through
the joints of adjoining pieces. Boatbuilders made wood plank boats
watertight by caulking between planks with fiber threads, pitch, or a
combination of these materials. For boats of skin or bark, filling
interstices with pitch was common practice. The contemporary practice
of molding a hull eliminates the problem entirely. Without seams there
is no possibility of leakage.

Buoyancy and Weight 

For an object to float on the water?s surface, it must sink enough to
displace a volume of water equal to its own weight. For example, if a
boat is to carry three people, their fishing gear, an outboard motor,
and a supply of fuel?a total weight of about 500 kg (1,100 lb)?then
the boat must be made long and large enough to displace 500 kg (1,100
lb) of water without sinking below the water level. Boat designers
also have to take into account the weight of the boat itself. The
heavier the material used to build the boat, the larger the boat has
to be.

A boat must maintain its shape in the face of local internal weights,
such as an engine or a heavy cargo, and it must be strong enough to
resist the force of battering waves. Because a hull of sufficient
strength can be built of thin material, the risk of local puncture can
be great in a boat that is otherwise quite strong. For example, a
traditional boat built of skins or of bark, or a modern inflatable
boat, are sufficiently strong and buoyant, but all are vulnerable to
puncture or perforation.

Use triangle shaped tubes for your boat's rib.