Dowty Marine and Dowty Turbocraft - Remembered by Adrian Waddams

My early love of boating as a boy was kindled by the Dowty Turbocraft, and I retain a great affection for what was a pioneering application of water jet marine propulsion.  As well as the history and development of the Turbocraft I developed an interest in other applications of Dowty water jet marine propulsion systems.

First pioneered by C W F Hamilton and Co of New Zealand and manufactured and developed under licence by Dowty Marine Ltd in the UK and Canada, Dowty became a major producer of water jet propulsion systems.   By way of background I am a Chartered Mechanical Engineer, a Fellow of the Institution of Mechanical Engineers and a member of the Royal Institution of Naval Architects, and now happily retired after an interesting career that included working in the marine industry.

I owned and restored a 1962 MkII Dowty Turbocraft during the 1970s, and subsequently published two articles about the Dowty Turbocraft and my experiences with it.  I did this to ensure the Dowty Turbocraft was not forgotten and to provide a historical record about how important it was.  The first article was in Classic Boat Magazine, November 2010, timed for the 50th anniversary of the Turbocraft’s launch, and the latter an enhanced version of this in Motorboat Owner Magazine in September 2015 which is an on-line only free publication.  Both articles are reproduced here in the Dowty Heritage archive.

The Turbocraft articles include images from original Dowty brochures and photographs plus my own contemporary photographs taken during my ownership of a MkII Turbocraft in the 1970s.  The boat in question was first owned by my cousin from 1963 so as a teenager living in Brighton I grew up with it, and took ownership around 1973 as my articles explain.

From 1977-79 as a young design engineer I worked for Rotork Marine in Poole, and found myself developing and testing a pair of Combat Support Boats (CSB) for evaluation trials by the US Army as Bridge Erection Boats.  Developed from the Rotork 8 metre Series 5 Sea Truck, built in GRP, these craft had two 12-inch diameter Dowty water jets driven by specially marinised GM Detroit 4-53T diesel engines each rated at 200bhp@2800 rpm.  These 12-inch jets were a variant of the propulsion units used in amphibious vehicles such as the Alvis Stalwart.

With 400bhp the Rotork CSBs could travel at 20 knots free running, but were primarily designed to develop 2 tons of static thrust to push or pull heavy floating bridge pontoons into place in shallow water.

Two engineers from Dowty Marine worked with us at Rotork on the CSB project, namely Bert Copp and George Ronson.  These gentlemen had been involved with development of the Turbocraft from the outset in 1959 and improved the jet steering nozzle and reverse deflector from the original design of CWF Hamilton and Co.  This can be seen in the Turbocraft engine and jet installation drawing I have added to the archive, whereby the steering control is brought inboard, and the jet deflector bucket is a fully contoured light alloy casting for improved reverse thrust.  The external mechanism is then protected under a moulded GRP cover, as seen in some of the photographs, and applies to MkII and MkIII versions from around 1961/2 onwards.

During my time at Rotork I was able to launch my Turbocraft from the factory slipway, and use her in Poole Harbour.  My contacts at Dowty provided me with a copy of the report on the Dowty Turbocraft towing tank tests carried out by Saunders Roe of East Cowes, IoW in 1959.  The tests used a 1/4 scale wooden model of the Dowty Turbocraft commissioned by the boat’s famous designer Fred Cooper and made by Attrills Boatyard at Bembridge, who also made the production moulds for the GRP Turbocraft hulls.   A copy of this report is in the Dowty Heritage Archive with photographs, lines drawings and test results.  The hull design for all marks of the Dowty Turbocraft from MkI to III was finalised after this report was issued.

I am not sure when Dowty Turbocraft production ended, or how many were made, but I believe it was around 1965 with the final MkIII boats manufactured by Watercraft Ltd of Shoreham-by-Sea, Sussex.  Perhaps someone can provide this missing information?

Further work at Rotork Marine included larger 12 metre Sea Trucks with Hamilton 1031 water Jets, for commercial applications.  From 1979 my subsequent career left marine propulsion behind, although I did enjoy further spells in the marine industry.  To this day I have great memories of my beloved Dowty Turbocraft with its smooth, throaty Ford Zephyr engine and unique handling characteristics.

I learned many of my practical skills working on the boat, water jet unit and engine, no doubt helping to nurture my interest in mechanical engineering as well as boat design.  As a final anecdote, I took my driving test in 1966 and passed first time driving my late father’s 1963 Ford Zodiac, so I enjoyed driving both the car and boat powered by the same Ford 6 cylinder engine.

I have provided to the Dowty Heritage archive with a number of scanned Turbocraft brochures, period photographs and extracts from Ford Marine Power brochures, the latter showing pictures of a MkII Turbocraft identical to mine with the covered external jet unit mechanism, squared engine and jet cover and lowered centre front seat backrest.  Plus there is the full towing tank test report and lines plan.

For action films of the Dowty Turbocraft there are some interesting period newsreels by Pathe News on the launching of the Turbocraft in 1959/60, including with Donald Campbell driving, and a more recent video of the rare Healey Marine 707 jet boat also using a Dowty water jet with the more powerful 3 litre Austin-Healey 3000 sports car engine.

These can be found on YouTube by clicking on links below:

Adrian Waddams

April 2019

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