My Dowty as purchased. Looks OK, but on break down not so good , neither was the trailer
The stern and its antiquated steering nozzle arrangement. Steering cables had no guides through the hull so acted like a saw through the stern
Dowty data – 1958 UK built Turbocraft
Length: 14’6″ (4.42 metres)
Beam: 5’9″ (1.52 metres)
Draught: 9″ (0.27 metre)
Power Unit: Marinised Ford Zephyr MK 11
Propulsion Unit: Dowty-Hamilton Chinook Marine Jet (2 stage)
Maximum Speed (1958): 35 M.P.H. (56 KPH)
Dry Weight: 1 ,350 lbs (612.35 KG)
Fuel Capacity: 10 Imperial Gallons (37.85 Litres)
Seating Capacity: Up to 5
Interior looked OK and was serviceable but not solid and I wanted to use the boat to its maximum
Dowty Engine and Water Jet Restoration
The original engine had a cracked block, so I purchased another and rebuilt it. Right is the result a lovely Ford Zephyr straight 6 – 2500cc engine. The replacement block came from an RAF compressor for starting jet engines
The sequence of the break-down and rebuild at the moment is likely to change as it is a large piece of work.
Engine repair was simple. The water jet dismantling was difficult. Help was found with an excellent Toolmaker friend who manufactured some of the obsolete parts, mostly in stainless steel and aluminium. Below is a large, pictorial file on the strip down and rebuild of the boat with basic details:
Replacement engine 
Not too bad 
Dowty Manifold 
Engine rebuilt 
New wiring 
Electronic distributor 
Nicely hidden electronic internals 
Activation tube-note washers at stern, these should be 1/2 moon bands 
Wierd steering 
Jet outlet 
Reduction nozzle 
Steering flaps 
Reverse guile (left broken) Right new one 
Steering, reverse & exit nozzle 
Reverse rollers 
outer impeller 
Impeller blade – stainless 
Activation tube – stainless 
Straightener blades 
Cutlass bearing shim between blades 
Inner blade 
Warer leak area 
Activation tube removed – reverse link above 
Rats evicted 
Jet base plate removed 
Serious leak under base plate 
Engine support 
Engine support 
Drive shaft coupling 
Removing coupling 
Massive chunk out of main bearing 
Bearing pot – hard to remove 
Lead telltale inserts to indicate removal 
Old seals 
Prop with seal holder sleeve 
Cuts in prop tube from seal 
Spacer and cutlass bearing sleeve 
Removing cutlass bearing
Ensure when replacing the cutlass bearing, the correct end is set up for the ‘Leading Edge’, which is marked on the edge.
Dowty jet unit rebuild
New & old cutlass bearing converted barge steering bush 
Cutlass bearing ready for fitting into activation unit 
Fitted-ensure you read the edge for the correct end 
1st impeller fitted 
2nd impeller fitted 
Intake housing ready for assembly 
Bearing pot and cover 
Bearing pot 
Bearing pot parts 
Bearing pot and seals placed in following 
Seal fitting sequence 
Bearing with drive sleeve 
Bearing pot housing-note marker to see if been off before 
Seal ready for cover 
Loose assy waiting drive coupling, then respray whole unit
A word about the main bearing. This displays the vital importance of setting up the ‘thrust’ spacers. Setting up is the most difficult part of the jet unit assembly. You can see clearly that the bearing has pushed out the side of the inner bearing holder and also a slice in the outer bearing shell. That in turn would chew up the seals, both oil and water.
Assembled drive shaft after full refurbish. Note new sleeve behind 2nd (inner) impeller. The shaft is 1 metre long. There are 9 seals and 1 massive bearing in it, plus a cutlass bearing between the impellers.
Dowty jet unit base plate re-manufacture
Possibly the worst job of all. It required the valuable help of a foundry, toolmaker and a fibreglass expert, large milling machine, specialist alloy welder and of course me.
Old jet intake base plate extracted from hull, very difficult job 
Tried welding torn threads-no good 
So new cast alloy base plate cast 
Inserts top-bottom to increase performance and reduce leaks. Drilling and tapping of holes was a chore, due to the accuracy required 
Easy job-new gasket 3mm synth cork 
New base plate inserted-dreadful job required F1 fibreglass specialists help 
Test fit-looking good 
Original exit and steering for jet 
Having a bit of fun (all returnable to original) fitting a large jet-ski nozzle and bucket for better power output, reverse and steering control 
New engine frame 
New dashboard, trial fit much more to do. More to come on all these items.
IMPORTANT NOTE: The base plate has an inherited weakness. The weakest point for leaks and rarely found is at the rear of the intake housing, take a look at ‘Inlet casing’ picture, there is a dark stain below the water exit‘. Pressure of the water being forced out of the exit nozzle causes the seal and even the fibreglass structure to break down. These water-jets produce a considerable amount of pressure.
Dowty Forward/Reverse shift mechanism
Gear box for reverse-forward 
Start of disassembly 
Oil bath and helical gears 
Shift box 
F/R shift bearing front end 
Huge shift shaft 12 foot 
F/R shift stern 
Bottom of shift box 
F/R slots in shift box
Dowty trailer replacement
Original Trailer-Not Good 
New wheels,axle & suspension 
I have started new trailer 
Little extras added 
Upgraded chassis 
More little extras 
Done and galvanised – temp mudguards
Dowty Dashboard
Old plastic dash 
Marking out new dash for gauges 
Trial gauge and switch fit 
Gauge and switch fitting after powder coat