Not only is it possible to build a boat from corrugated cardboard, but you can fit up to 10 people in it and sail many times throughout the competition. So why do some boats sink when they hit the water, and others float like a bob? It's all in the ingredients.

Following are the secrets to building a seaworthy boat, as well as where to get the material.   Here's everything you need to know.

Class I Boat
Boats in this class must be propelled by canoe or kayak oars, or paddles. These propulsion tools, as well as their decorations, may be constructed from materials other than cardboard. ALL OTHER PARTS of the boat must be corrugated cardboard. This includes the hull, decking, cowling, superstructure, oar locks, seating and rudder. Get as creative as you want -- just think cardboard. Nuts, bolts, washers and staples are not allowed.

Class II Boat
Class II boats must meet the requirements of Class I boats, with the exception of the propulsion and steering systems. Here's an opportunity to test your survivor skills.

The muscle-powered propulsion system (propellers, paddle wheels, sails) and the steering system (rudders) do not need to be made of cardboard, but materials used must not contribute significantly to the structural rigidity of the boat. Propulsion and steering systems must be designed and fabricated by the boat building team. In addition, the connection between the propulsion and steering systems must be made of corrugated cardboard.

Important Construction Rules
• Any thickness of corrugated cardboard is permitted, but waxed cardboard, carpet tubes and barrels are not allowed.
• Only duct tape may be used. Tape may be used on seams, joints or patches. Do not wrap the hull in tape, plastic, shrink wrap or any other material.
• Caulking may be used, but only on seams and edges.
• A one-part enamel or lacquer paint and/or polyurethane varnish or water seal is permitted. Do not use tar-based substances, epoxy glue, fiberglass resin or any two-part substance, including two-part varnishes and paint. Applied paint must be allowed to dry for at least 24 hours prior to launching.
• Styrofoam or any other flotation-type foam is a major no-no. Violators will be branded "Pirates" and will be stripped of any trophies.

Boat Building Basics

Develop A Concept
Determine race category to enter, Class I or II boats
Sketch your creative ideas on paper
Calculate length, width, height, draft, balance
Consider size and weight of crew
Build a scale model

Preparing For Construction
Secure adequate work and storage space
Gather supplies

Suggested Supplies
Corrugated cardboard - three layers for floor, two layers for walls
Acrylic latex caulk
String line for straight edge; right angle or squaring tool
Carpet knife or Exacto knife, extra blades
Wood glue, Liquid Nail panel adhesive, or DAP contact cement
Water seal, polyurethane
Foam brush
Paint brush or roller
Paint, including latex house paint
Paper tape, masking tape
Creasing tool (scissors work well)
Clamps (spring & quick)
Measuring tape
Duct tape

Construction Steps
Transfer model or concept to cardboard
Mark lines
Cut cardboard
Bend cardboard
Brace
Glue
Tape
Seal
Waterproof with materials listed in Important Construction Rules

Being Creative
Develop a theme

Paddling
Types of paddles - canoe or kayak oars
Consider whether you'll be rowing alone or with others

Testing
Test prior to the event or take your chance on race day.