The cardboard boat made its first appearance in 1962, when Davis Pratt of Southern Illinois University built one as a physics project. In an effort to prove that cardboard could fulfill the principals of buoyancy, Pratt used corrugated paper to produce a craft that was eight feet (2.44 meters) long, 30 inches (76 centimeters)wide and 12 inches (30.5 centimeters) in depth, capable of carrying a 225-pound (102.6 kg) person. The cardboard boat itself weighed 20 pounds (9.07 kg).
In order to fulfill the goal of his project, Pratt's craft had to travel 100 feet (30.4 meters) without sinking, and it passed that test easily. It also attracted the attention of financially challenged boat lovers across the United States, and soon imitators were everywhere. Southern Illinois hosted a cardboard boat regatta in 1974, an event which expanded into dozens of similar races across the country. More than 30 years later, the most popular such event is the World's Championship Cardboard Boat Races on Greer's Ferry Lake in Heber Springs, AK.
Besides being inexpensive -- a typical cardboard boat can be built for under $50 U.S. Dollars (USD) -- these bargain-basement craft have gained popularity because of their versatility and ease of transport. Made from folded sheets of corrugated cardboard joined together with glue and duct or drywall tape and waterproofed at the joints and edges with contact cement, they can be formed into a wide variety of fanciful shapes. The only limitations on a cardboard boat are the imagination of the builders and the weight-bearing capacity of the craft itself. Competing boats at Heber Springs in recent years have included a six-passenger locomotive, a dragster and a giraffe.
But the cardboard boat has also grown beyond novelty status. With over 1,500 enthusiasts across the United States and worldwide, it is now used for recreation, fishing and kayaking. Generally propelled with kayak oars, it is not recommended for salt water, nor for use in rapids. Substances banned from competitive cardboat boating include epoxy, fiberglass, metal and pre-waxed cardboard. Some cardboat boats have lasted more than 20 years.