An improved airboat was invented in Utah in 1943 by Cecil Williams, Leo Young, and G. Hortin Jensen. Their boat, developed and used near Brigham City, Utah, is sometimes erroneously called the first airboat. At the Bear River Migratory Bird Refuge in northern Utah, Cecil S. Williams and G. Hortin Jensen sought a solution to the problem of conducting avian botulism studies in the shallow, marshy hinterlands. By installing a 40-horsepower Continental aircraft engine, purchased for $99.50, on 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.