How it began
Bill Hamilton, a self-taught engineer, ran Irishman Creek Station, a high-country sheep run in the South Island of New Zealand, and kept a workshop there. In 1951 he returned to an old idea of a boat that could travel up the shallow, fast rivers nearby. After his Christchurch factory took over production work, the station workshop became a research site for the project.
His first jet boat was a plywood hull of about 3.6 meters with a Ford engine driving a centrifugal pump. It was tested on the station dam and water race, then traveled up the Waitaki River in early 1954. Hamilton said he did not invent the waterjet itself. He credited the principle to Archimedes and described his own work as making it practical for boats.
Before it existed
Shallow braided rivers are hard on propellers and rudders, which hang below the hull and strike gravel. Hamilton's first attempts in 1951 used an air screw and a retractable marine propeller, and they did not work. He then followed the most successful earlier design, the American Hanley hydrojet, using a round centrifugal pump that drew in water and expelled it through a steerable nozzle under the boat. That arrangement reached about 11 miles per hour.
How it works
A waterjet draws water in through the bottom of the hull, speeds it up with a pump, and pushes it out the stern. The reaction drives the boat, and turning the nozzle steers it. The 1954 change that made the design work was to send the jet stream out above the waterline instead of below the boat. Speed rose to 17 miles per hour and nothing was left hanging under the hull. Later units replaced the centrifugal pump with axial-flow pumps in two or three stages, where water passes straight through and pressure builds at each stage.
How it spread
The first production unit, named Quinnat, used a vertical shaft and a right-angle gearbox. About 100 smaller Rainbow units were made and sold in New Zealand from 1956, and the more efficient Chinook axial-flow unit followed in 1957. The Colorado series of 1963 was a simpler design that halved the cost of a unit. Larger Work Jets for diesel commercial vessels arrived in 1970. Jet boats went on to run rivers including the Sun Kosi in Nepal, the Sepik, the Zaire, the Ganges and the Amazon, and were used for flood relief, surveying and recreation.
What changed first
In 1960 a team that included Hamilton's son Jon took jet boats down and up the Colorado River through the Grand Canyon, the first upstream run of the river. In 1961 Bill Hamilton received an OBE with a citation that named the design and construction of the jet-propelled motorboat. He retired from the company in 1965 and was knighted in 1974.
Where it stands today
HamiltonJet, the company Hamilton founded in 1939, stopped making industrial equipment in the late 1970s and early 1980s to focus on waterjets and controls. It remains family owned, employs more than 400 people, and says it has installed over 60,000 waterjets worldwide. Its units drive fast ferries, pilot boats, rescue and fire boats, military and patrol craft, and wind farm service vessels as well as recreational boats.
