RESTORATION PROJECT OF THE STRIP DOWN AND REBUILD OF BN’s 1958 DOWTY JET BOAT

Web by BN-WEBS 2012

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Dowty (Hamilton) Turbojet Boat Dowty Turbojet Boat History Jet Unit Trailer Engine Hull Respray Odd & Ends Throttle linkages Gratitude Page Links


The Beginnings:

From a backyard workshop at

Irishman Creek Station in

Central Otago 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.


Bill Hamilton's workshop

expanded over the years, until

in WWII it played an important

role in manufacture of munitions

and earthmoving equipment,

and in the training of

engineering personnel for the

war effort. With the coming of

peace in 1945, he moved

operations to Christchurch,

and as the new operation

prospered he found more time

to devote to new ideas.


Hamilton developed the water jet in response to the need to navigate the shallow waters rivers around his Irishman Creek Station. After fiddling unsuccessfully with airscrews 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 runabout, the jet unit achieved a speed of 11mph, a slow start.

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:

Currently employing 340 staff in New Zealand and 60 overseas, 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. The 10 - 60m range is defined at the lower end by the large number of manufacturers of light-duty water jets for recreational applications, and at the upper end by a few manufacturers as represented by the Rolls Royce-owned Swedish company KaMeWa.

Progress:

Further research and development of the Hamilton's initial design brought three fundament modifications which made the Hamilton Jet what it is today.

The first - expelling the water jet above, rather than below the waterline, significantly increased efficiency of the unit, and therefore thrust and speed.

The 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.

The 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 Original Hamilton Jet Boat

Dowty Handbook.pdf

This is the only copy of a handbook I could find