The first airboat, called the Ugly Duckling, was built in 1905 in Nova Scotia Canada by a team lead by Dr. Alexander Graham Bell. It was used to test various engines and prop configurations. An associate of Dr. Bell, Glen Hammond Curtiss (of airplane manufacturing fame) is reported to have registered the first airboat in Florida, USA in 1920. It was called the Curtis Scooter (Dreamers, Schemers and Scalawags By Stuart B. McIver: Chapter 28, Who Invented the Airboat?) and it had a closed cockpit design.
By the 1930's homemade airboats began appearing in the swamps and marshes of Florida and Louisiana. One company in Florida claims to have been providing airboat rides as entertainment since the mid 1930's. Over the years a variety of designs were tried and. through trail-and-error, the standard design used today arose. That is, 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. One well documented case of a homemade design (though not the first) was an airboat built by staff at the Bear River Bird Refugee near Brigham City, Utah in the 1940's. It appears to have involved collaborative efforts by three employees of the refuge - Leo young, G. Hortin Jensen and Cecil Williams.
A story in Ducks Unlimited magazine in 1987 mentioned Young and Jensen and dated the building of the first boat in 1950. Refuge records, however, show the first boat came into use in 1943, with several photos of running air boats dated 1947. Prior to the introduction of the airboat, refuge biologists had to either walk through shallow water and deep, sticky mud or push unpowered flat-bottom boats with long poles. Staff had experimented with a boat called the "Mud Queen," which had small paddle wheels on either side that pushed the boat. They build their first airboat nicknamed "Alligator I" from a flat-bottom boat pushed along by an aircraft engine purchased for $99.50. Young reported that he called the first airboat an "air-thrust boat." Once word got out about the boat, Leo Young built and sold boats all over the world.
Proud and (again) current member of the "Four Banger's Club"