a flat-bottomed 12-foot long aluminum boat, they built one of the first modern airboats. Their airboat had no seat, so the skipper was forced to kneel in the boat. They dubbed it the Alligator I as a response to a joking comment from US Fish and Wildlife Service headquarters that they should "get an alligator from Louisiana, saddle up and ride the critter during their botulism studies." Their airboat was the first to use an air rudder (a rudder directing the propeller exhaust rather than the water), a major improvement in modern airboat design. The purpose of Williams, Young, and Jensen's airboat was to help preserve and protect bird populations and animal life at the world's largest migratory game bird refuge. The Bear River Migratory Bird Refuge near Brigham City, Utah is a wetlands oasis amid the Great Basin Desert and an essential stopping point for birds migrating across North America. The need for a practical way to navigate a challenging environment of wetlands, shallow water, and thick mud helped inspire Williams, Young, and Jensen to create the flat-bottom airboat, which they initially called an "air thrust boat." Designs and subsequent improvements and practical use of the air thrust boats appears to have been a collaborative effort. LeeRue Allen, who worked at the Refuge since 1936 appears to have also been involved and helped to document a history of the events. Many of the early airboats built at the refuge in Utah were shipped to Florida. Early records show it cost roughly $1,600 to build a boat, including the engine. Over the years, the standard design evolved through trial-and-error: an open, flat bottom boat with an engine mounted on the back, the driver sitting in an elevated position, and a cage to protect the propeller from objects flying into them. Manufacture and design Airboat manufacturers tend to be small, family run businesses that assemble built-to-order boats. Most airboats are manufactured in the United States, although they are also built in Russia, Italy, Finland, Japan, Australia, and elsewhere. Prior to 1950, most airboats were manufactured in France by companies and individuals such as Farman, De Lambert, and René Couzinet. Modern, commercially manufactured airboat hulls are made of aluminum or fiberglass. The choice of material is determined by the type of terrain in which the vessel will be operated; airboats intended for use in icy conditions will have sturdier polymer coated aluminum