Dowty jet boats were invented by William Hamilton in New Zealand. They proved to be so good that countries like, Australia, Canada and the United Kingdom obtained licences to build the boats, using their local engines and building the Dowty hull in their country.
These boats are not only great fun, but add a real meaning to the word ‘work horse’. They were used as tough boats to go almost anywhere. They were like a waterborne off road vehicle.
Restored Dowty Turbocraft in Belfast under the famous Harland & Wolff Crane
Many famous people owned a Dowty water jet boat and they featured in Patrick McGoohans series of The Prisoner (clip below). He used one to make good his escape from the island he was trapped on in the series. Prince Charles and Donald Campbell had one as did many more. They were used on the Colorado River and in other wild places due to their amazing versatility, power, speed and shallow draft.
The beginnings from a backyard workshop at Irishman Creek Station in Central Otago, New Zealand in the 1920s, to multi-million dollar international enterprise in Christchurch in the 2000s. The story of Bill Hamilton and the Hamilton Jet is surely a pinnacle in the history of backyard tinkering in New Zealand.
William Hamilton’s workshop expanded over the years and with the coming of peace in 1945, he moved operations to Christchurch. Hamilton developed the water jet in response to the need to navigate the shallow water rivers around his Irishman Creek Station. After some unsuccessful trials with air screws and retractable propellers, his first success came with a vertical centrifugal pump powered by a Ford 10 engine through a bevel gear. Mounted in a 3.5m wooden runabout, the jet unit achieved a speed of 11mph, a slow start, but a positive one.
The potential of the concept led Hamilton to hire a young engineer, George Davison, as his assistant in improving the jet unit. Davison’s engineering training, combined with Hamilton’s hands-on approach proved the ideal combination. The concept took off, and the two never looked back. Today Hamilton Jet is now one of New Zealand’s top export earners in the marine industry, exporting almost all of its production to more than 45 countries world-wide.
The company has carved a niche in water jets for craft in the 10 – 60m range, a market in which it has consistently expanded its share. Progress, further research and development of the Hamilton’s initial design brought three fundamental modifications which made the Hamilton Jet what it is today:
First – expelling the water jet above, rather than below the waterline, significantly increased efficiency of the unit, and therefore thrust and speed.
Second -eliminating the bevel gear, brought increased mechanical efficiency. This modification was incorporated in the first commercial units manufactured in 1956. Known as the Rainbow Jet unit, this design featured marine parts such as a centrifugal pump connected directly to the motor, without the need for a noisy and inefficient right-angle bevel drive. Designed for light runabouts, the Rainbow Jet was sold in limited numbers in New Zealand.
Third – eliminating the tortuous and inefficient path through the centrifugal pump, further improved efficiency, and established the fundamental design of the axial-flow jet unit as we know it today.
The axial-flow concept was further improved with development of two and three-stage axial systems developing greater pressures, and incorporated in the Chinook Series in 1957, and the Colorado Series in 1963. In 1959, the Hamilton Jet took on the Colorado River through the Grand Canyon. Over the next few years the team repeatedly visited the Colorado while building the profile of the company in the US market. The Colorado Series of jet units, developed in response to demands for greater simplicity and lower cost, proved a milestone in the development of the Hamilton Jet. The Colorado Series halved the cost of jet units, and reached a wider market, covering everything from small fizz boats to large off-shore racing craft.
As worldwide interest in the Hamilton jet increased, the company began work on the ‘Work Jets System’, introduced to the market in 1970, larger and more robust than previous models, the Work Jets were designed for diesel-powered commercial vessels where high loads and prolonged operation is the norm. The Work Jets Series formed the basis of the HM Series, since developed and refined into the sophisticated HS and HJ Series.
In keeping with the trend towards increasing computerisation, the early 1990s saw the company introduce electronic control systems to manage the increasingly complex units, culminating in today’s ‘blue ARROW’ water jet control system.
The Prisoner escaping from a bizarre situation in a Dowty Turbocraft. (Slow start of film)