U.S. Crash Boats Emblem
U.S. Crash Boats

Small Boats, Groups 1 & 2

Small Boats  - Group One
The following, although with separate design numbers, were considered to be one basic group of boats. The 24 ft. boat was a Chris-Craft civilian design. About 1950 the USAF started designating these as R-4-*** boats. Assorted small boats of 38 feet and under were used in inland waters:
Boat Type                             Design No.            No. Built                            Length
38ft Rescue Boat                        388                        48                                    38’
36ft Rescue Boat                        382                      102                                    36’ 
31ft Rescue Boat                        387                        30                                    31’  10”
24ft Rescue Boat*                      326                         60                                    24’
18ft Swamp Glider (Airboat)       415                       113                                    18’
TOTAL BOATS                                                       353  
* Some records show 24ft and others 22ft, all show the design as 326
The Navy also had a 34 ft crash boat in their inventory, powered by a single Kermath "Sea Raider" engine but the quantity has not been found.
Swamp Gliders
R-24-1422, a 24ft swamp glider staioned at Kisarazy AFB, on Tokyo Bay, 1955. The 24ft glider was a larger version of the 18ft, WWII glider, with the driver sitting higher for improved visibility. It is miliatry, so of course its bigger, better and more expensive.
The Swamp Glider is also known as an airboat, swamp boat, or bayou boat. The version used by the AAF was a flat-bottomed boat propelled by an aircraft propeller and powered by an aircraft engine. In the AAF they were not recorded as “P” boats as were the larger rescue craft but as “SG” boats. 
The first airboat was the Ugly Duckling, an aircraft propeller testing vehicle built in 1905 in Canada by a team led by Dr. Alexander Graham Bell. Farman Aircraft, the company that built the engines for the WWI military airboats was an early builder but pulled out of the boat business by the end of the 1920s.
In the United States, Glenn Curtiss is credited with building a type of airboat in 1920 to access the Florida backwoods. Airboats began to become popular in the United States in the 1930s, when they were independently "invented" and used by a number of Floridians, most living in or around the Everglades.  Some Floridians who invented their own airboats include frog hunter Johnny Lamb, who built a 75-horsepower airboat in 1933 and Ernest and Willard Yates, who built an airboat in 1935 that they steered via reins attached to a crude wooden rudder.  Yates was the first person to die in an airboating accident, when the engine dislodged and sent the spinning propeller into him.
By the time gliders went into military rescue service the engine and propeller were enclosed in a protective metal cage to prevent objects, such as tree limbs, clothing, or wildlife, from contacting the whirling propeller, which can cause severe injury to the operator and damage the swamp glider.
During World War II, Army Air Forces training fields dotted the whole state of Florida and the Gulf Coast from Florida to Texas. Pilots in training had plenty of crashes into the coastal marshes, bayous, and swamps that were almost impenetrable. The glider that had evolved from the efforts of the various inventers was a boat of extremely shallow draft, propelled and directed from above the water. The characteristic flat-bottomed design of the airboat, in conjunction with the fact that there are no operating parts below the waterline, allows for easy navigation through shallow swamps and marshes; in canals, rivers, and lakes; and even on ice and frozen lakes.
The airboat is pushed forward by the propeller. Steering is accomplished by diverting that column of air left or right as it passes across the rudder, mounted behind the propeller, which the pilot controls with a steering wheel on the AAF/USAF swamp gliders. Overall steering and control are a function of water current, wind, water depth, and propeller thrust.
Among those Floridians who claimed to have invented the swamp glider was the namesake of Paul Prigg Boat Works near Miami. It was a small, very clean operation, with Paul's home attached. Paul was a boat builder and private pilot before the war. In an article in a 1946 issue of Motor Boating he claimed to have birthed the swamp glider from the knowledge acquired in pursuing those interests. He developed the design of the AAF swamp glider and had little trouble convincing the AAF of their need for the boats. He further stated that he convinced them that the boats should be stationed in “out of the way places” remote from the bases for quicker response time. Paul Prigg Boat Works appears to have built all of the Word War II era swamp gliders as production records show that he was contracted to build numbers SW-1 through SW-113, which appears to be the total in AAF service. Other sources state that Prigg built 188 boats and another 17 were built by other builders but I cannot confirm those numbers.
An improved airboat was invented in Utah in 1943 by Cecil Williams, Leo Young, and G. Hortin Jensen.  Their boat, is sometimes erroneously called the first airboat. By installing a 40-horsepower Continental aircraft engine on a flat-bottomed 12-foot long aluminum boat, they built one of the first modern airboats. Airboat manufacturers tend to be small, family run businesses that assemble built-to-order boats.
Today airboats continue to be a very popular means of transportation in marshy and/or shallow waters, most in the Everglades, the Indian River Lagoon, and the Kissimmee and St. Johns rivers, all of which are in Florida. They are also extensively used in the Louisiana bayous and internationally, the Mekong River and Delta in Vietnam, as well as the Mesopotamian Marshes.
In modern airboats the operator and passengers, are typically seated in elevated seats that allow visibility over swamp vegetation. High visibility lets the operator and passengers see floating objects, stumps, other submerged obstacles, and animals in the boat's path. This does make them very top heavy and suitable only for protected waters.
Boats in the Forties - Group Two
Design 385 and 221 – 45 & 42ft boats for use in inland and coastal waters were considered to be a second group. Their combined total production was 163 boats. They were recreational boat designs drafted for war time use.
The 42 ft. boat was twin screw,most sources indicate that it was designed  by Owens Yachts as Design 221 and built by both Owens and Chris Craft, although Chris Craft primarily built Higgins boats. There are two sheets at the Mariners' Museum dated 1941 and credited to "Marine Design and Construction / Quartermaster Corps, U.S.A. One sheet shows the lines and offsets while the other shows the sections. While the boat was most likely a civilian design, the drawings may include modifications for military use. Most, if not all of these boats, were produced in 1941 and 1942.
Occasionally an army 40 ft. boat will be found Built by Palmer Scott & Co. of New Bedford Massachussetts but they were classified as passenger boats and were given "J" numbers. There were about 157 of these boats built between 1941 and 1944 by Palmer Scott & Co. There may still be other builders that remain unfound.