Hamilton Jet HJ212 Manual

HJ212
Installation and Service Manual
R3A3
Jet unit Manual

Copyright © 2002. C.W.F. Hamilton Ltd
All rights reserved. No part of this document may be reproduced, stored in a retrieval system or transmitted
in any form or by any means; electronic, electrostatic, magnetic tape, mechanical, photocopying, recording
or otherwise, without permission in writing from C.W.F. Hamilton & Co Ltd.
Due to our policy of continuous development, specifications in this document are subject to change without
notice or obligation.
Jet or control type
HJ212
Part number
089212
Revision
R3
01/01/14
Amendment
A3
03/02/15

Contents
1 - Introduction _______________________________________________________1-1
Limited Warranty _________________________________________________________ 1-1
Warranty and Ownership Registration Form ___________________________________ 1-3
General Safety Notice _____________________________________________________ 1-4
2 - Product Description ______________________________________________2-1
Introduction _____________________________________________________________ 2-1
Equipment Description ____________________________________________________ 2-2
Main Components __________________________________________________ 2-3
3 - Design Basics ______________________________________________________3-1
Propulsion System Design __________________________________________________ 3-1
Hull Design ________________________________________________________ 3-1
Drive Lines ______________________________________________________________ 3-4
Requirements of the Driveline _________________________________________ 3-4
H-Bar Drive Lines____________________________________________________ 3-4
Engineering Checks__________________________________________________ 3-5
Driveline Options ___________________________________________________ 3-5
Universal Driveshaft Alignment ______________________________________________ 3-5
Jet Coupling Flange Details____________________________________________ 3-6
Drivelines for Diesel Engines __________________________________________ 3-6
Moments of Inertia__________________________________________________ 3-7
Mainshaft Dimensions _______________________________________________ 3-7
Critical Speed of Mainshaft ___________________________________________ 3-8
Jet Mainshaft Alignment ___________________________________________________ 3-8
Water Offtake____________________________________________________________ 3-9
Conventional Water Pickup ___________________________________________ 3-9
Engine Location and Mounting _____________________________________________ 3-10

Engine mounting___________________________________________________ 3-10
Engine systems ____________________________________________________ 3-10
Exhaust systems ___________________________________________________ 3-11
Governor settings __________________________________________________ 3-11
Dry run kit (optional extra) ________________________________________________ 3-12
Scope of use ______________________________________________________ 3-12
4 - Precautions Against Corrosion _________________________________4-1
General _________________________________________________________________ 4-1
Electrical Wiring System ______________________________________________ 4-1
D.C. Systems _______________________________________________________ 4-2
A.C. Systems _______________________________________________________ 4-2
Shore Connections ________________________________________________________ 4-2
Using an Isolating Transformer ________________________________________ 4-2
Using a Galvanic Isolator _____________________________________________ 4-3
Earth Bonding System _____________________________________________________ 4-3
Corrosion Monitor ________________________________________________________ 4-4
Trim Tabs and Other Submerged Fittings ______________________________________ 4-4
Earth Connections for Electronic Equipment ___________________________________ 4-4
Anodes _________________________________________________________________ 4-5
Jet Unit Anodes_____________________________________________________ 4-5
Hull Anodes ________________________________________________________ 4-5
Anti Fouling Paint _________________________________________________________ 4-5
Anti-Seize Compound______________________________________________________ 4-5
Impressed Current Protection _______________________________________________ 4-6
Steel Hulls and Carbon Fibre Reinforced F.R.P. Hulls _____________________________ 4-6
Earth Bonding System (Not Normally Current Conducting) __________________ 4-6
Checking the Insulation ______________________________________________ 4-6
5 - Installation_________________________________________________________5-1
GRP Hull intake block ________________________________________________ 5-1
Aluminium hull intake block___________________________________________ 5-1
Hull Preparation __________________________________________________________ 5-2

Fixing the Intake Block to the Hull ______________________________________ 5-2
Transom Preparation ________________________________________________ 5-2
Equipment Preparation ____________________________________________________ 5-3
Steering Components ________________________________________________ 5-3
Reverse Components ________________________________________________ 5-3
Mounting the Jet Unit _____________________________________________________ 5-3
Preparation ________________________________________________________ 5-3
Mounting the Jet Unit________________________________________________ 5-4
Fix the Transom Plate to the Hull_______________________________________ 5-4
Installation Checks for the Jet Unit _____________________________________ 5-4
Final Assembly _____________________________________________________ 5-6
Driveline and Engine Installation _______________________________________ 5-6
Engine Cooling ____________________________________________________ 5-10
Engine Systems ____________________________________________________ 5-10
Exhaust Systems ___________________________________________________ 5-10
Optional Impeller Installation_________________________________________ 5-10
Installation of Control Equipment ___________________________________________ 5-10
Reverse Latch Assembly _____________________________________________ 5-11
Reverse Cable _____________________________________________________ 5-11
Zero Speed Detent _________________________________________________ 5-12
Steering Installation ______________________________________________________ 5-13
Steering Wheel Number of Turns______________________________________ 5-13
Tiller Stop Fitting and Adjustment _____________________________________ 5-13
Cable Pulley System ________________________________________________ 5-14
Push-Pull Cable System______________________________________________ 5-14
Transom Preparation _______________________________________________ 5-14
6 - Commissioning____________________________________________________6-1
Pre-Launch Checks ________________________________________________________ 6-1
Post Launch Checks _______________________________________________________ 6-2
Engine Running Checks (Vessel Moored) ______________________________________ 6-2
Vessel Speed and Handling Trials ____________________________________________ 6-3
After Initial Trials (After Engine Shutdown) ____________________________________ 6-3

7 - Fault Finding_______________________________________________________7-1
System Faults ____________________________________________________________ 7-1
Jet Unit Faults____________________________________________________________ 7-1
Engine RPM increases suddenly________________________________________ 7-1
Engine RPM decreases _______________________________________________ 7-1
Water leaking from under the bearing housing ___________________________ 7-2
Loud high pitched rattling whine _______________________________________ 7-2
Excessive vibrations, gradually increasing ________________________________ 7-2
Engine RPM increases gradually over a period of time______________________ 7-2
Sudden increase in vibration from the jet unit ____________________________ 7-2
Gradual increase in vibration from the jet unit ____________________________ 7-2
Low engine RPM ____________________________________________________ 7-3
Thrust bearing excessively hot _________________________________________ 7-3
Dry run faults ____________________________________________________________ 7-3
Bearing seizes when dry running _______________________________________ 7-3
Changing sound from the jet unit ______________________________________ 7-3
Excessive scouring of the shaft sleeve ___________________________________ 7-3
Reverse System Faults _____________________________________________________ 7-4
Steering System Faults _____________________________________________________ 7-5
Steering nozzle slow to respond _______________________________________ 7-5
Steering jamming ___________________________________________________ 7-5
8 - Maintenance _______________________________________________________8-1
General _________________________________________________________________ 8-1
Salt Water Operation ________________________________________________ 8-2
Jet surface coating procedure _______________________________________________ 8-2
Introduction and scope_______________________________________________ 8-2
Application of Antifoul Coatings________________________________________ 8-2
Maintenance of Waterjet Coatings _____________________________________ 8-3
Preservation (Pre Installation) _______________________________________________ 8-7
Preservation (Post Installation) ______________________________________________ 8-8
Servicing Intervals ________________________________________________________ 8-8
HJ Jet Unit Service Intervals ___________________________________________ 8-9
Daily "pre use" servicing checks_______________________________________ 8-10

Jet Unit Servicing Details __________________________________________________ 8-10
Internal Water Path: ________________________________________________ 8-10
Thrust Bearing_____________________________________________________ 8-11
Water Seal: _______________________________________________________ 8-11
Anodes: __________________________________________________________ 8-11
Steering System ___________________________________________________ 8-12
Reverse Shaft and Bushes____________________________________________ 8-13
Reverse Linkages: __________________________________________________ 8-13
H Bar or Driveshaft Universal Joints____________________________________ 8-13
Engine Alignment:__________________________________________________ 8-13
Jet Unit ________________________________________________________________ 8-13
Impeller blades: ___________________________________________________ 8-13
Impeller check for wear and damage: __________________________________ 8-14
Marine bearing: ___________________________________________________ 8-14
Reverse duct ______________________________________________________ 8-14
Splash Guard ______________________________________________________ 8-14
Tailpipe, nozzle and nozzle housing ____________________________________ 8-14
Jet unit paintwork: _________________________________________________ 8-14
Excessive wear: ____________________________________________________ 8-15
Control System __________________________________________________________ 8-15
Checking the steering system_________________________________________ 8-15
Checking the Reverse Linkages _______________________________________ 8-17
Laying Up_________________________________________________________ 8-18
Tools __________________________________________________________________ 8-18
Threaded Fasteners ______________________________________________________ 8-19
Thread locking agents_______________________________________________ 8-19
Recommended Oils and Lubricants __________________________________________ 8-19
9 - Overhaul____________________________________________________________9-1
General Information_______________________________________________________ 9-2
Introduction _______________________________________________________ 9-3
Care of Jet Unit Paintwork ____________________________________________ 9-4
Torquing Sequence of Nuts ___________________________________________ 9-4
Anode Replacement _________________________________________________ 9-4
Refitting the Locating Dowels__________________________________________ 9-5

Reverse Assembly Overhaul ________________________________________________ 9-6
Reverse Duct Removal _______________________________________________ 9-6
Reverse Duct Overhaul _______________________________________________ 9-6
Reverse Link Removal and Inspection ___________________________________ 9-7
Bush and O-Ring Replacement _________________________________________ 9-7
Reverse Shaft Shouldered Bush Replacement_____________________________ 9-8
Latch System Removal and Overhaul____________________________________ 9-8
Latch System Checking for Wear _______________________________________ 9-9
Reverse Assembly Refitting ___________________________________________ 9-9
Steering Assembly Overhaul _______________________________________________ 9-12
Remove the Steering Shaft ___________________________________________ 9-12
Steering Nozzle Assembly Removal ____________________________________ 9-13
Steering Assembly Re-Fitting _________________________________________ 9-15
Bearing Housing Assembly overhaul _________________________________________ 9-18
Bearing Housing and Water Seal Assembly Dismantling____________________ 9-18
Inspect the Bearing Assembly and Water Seal ___________________________ 9-19
Reassemble the Bearing Housing and Water Seal_________________________ 9-20
Tailpipe Area Overhaul____________________________________________________ 9-22
Impeller - Checking for wear _________________________________________ 9-22
Marine water bearing - Checking for wear ______________________________ 9-22
Tailpipe Area Dismantling _________________________________________________ 9-23
Tailpipe, Marine Bearing and Wear Ring Inspection_____________________________ 9-23
Wear Ring Removal and Replacement _______________________________________ 9-23
Removal of the wear ring and insulator strip ____________________________ 9-24
Preparing a new wear ring for fitting ___________________________________ 9-24
Fitting a new insulator ______________________________________________ 9-25
Fitting a new wear ring ______________________________________________ 9-25
Impeller Overhaul________________________________________________________ 9-27
Inspection ________________________________________________________ 9-27
Blade leading edge repair procedure___________________________________ 9-27
Impeller outside diameter (O.D.) repair procedure _______________________ 9-28
Balancing _________________________________________________________ 9-28
Passivation _______________________________________________________ 9-29
Marine Bearing Replacement ______________________________________________ 9-29
Dry Run Bearing _________________________________________________________ 9-30
Dry Run Bearing Graphic ____________________________________________ 9-30
Tailpipe and Impeller Reassembly ___________________________________________ 9-31

Transom Plate Assembly Overhaul __________________________________________ 9-31
Transom Plate Removal _____________________________________________ 9-31
Transom Plate Refitting _____________________________________________ 9-32
Intake Screen ___________________________________________________________ 9-32
Intake Screen Removal ______________________________________________ 9-32
Intake Screen Refitting ______________________________________________ 9-32
Hatch Extension _________________________________________________________ 9-33
Hatch Extension Fitting______________________________________________ 9-33
Hatch Extension Removal ____________________________________________ 9-34
10 - Appendix _______________________________________________________ 10-1
Conversions ____________________________________________________________ 10-2
Loctite Application Guide__________________________________________________ 10-3
General Practice ___________________________________________________ 10-3
Primers, Activators and Accelerators___________________________________ 10-3
Equivalents _______________________________________________________ 10-4
KMT Nut Fitting and Removal _____________________________________________ 10-12
Installation Checks ______________________________________________________ 10-14
Jet Unit Mounting _________________________________________________ 10-14
Jet Unit General __________________________________________________ 10-15
Jet Systems Steering _______________________________________________ 10-16
Drive Shaft_______________________________________________________ 10-17
Commissioning Checks___________________________________________________ 10-18
Pre Launch Checks ________________________________________________ 10-18
Post Launch Checks________________________________________________ 10-19
Engine Checks (Vessel Moored) ______________________________________ 10-20
Vessel Trial ______________________________________________________ 10-22
After Initial Trials__________________________________________________ 10-23
Jet Unit Trials & Commissioning Data _________________________________ 10-24
Temperature Readings _____________________________________________ 10-24
Speed Trial Readings_______________________________________________ 10-24
Aluminium Weld Procedure_______________________________________________ 10-26
Tightening Torques _____________________________________________________ 10-28
Nut Tightening Torque _____________________________________________ 10-28
Screw Tightening Torques __________________________________________ 10-29

Stud Installation __________________________________________________ 10-30
Set Screws _______________________________________________________ 10-30
Hydraulic Cylinder Piston ___________________________________________ 10-31
Hydraulic Fittings _________________________________________________ 10-31
Thread Lubricants _________________________________________________ 10-33
Recommendations for Lubricants and Oils ___________________________________ 10-34
Hydraulic Fluids___________________________________________________ 10-34
Bearing Housing Lubrication ________________________________________ 10-36
Joint Lubrication __________________________________________________ 10-37
Drivers Guide __________________________________________________________ 10-38
Starting Up ______________________________________________________ 10-38
Ahead, Zero Speed and Astern Controls _______________________________ 10-39
Power Assisted Slowdown __________________________________________ 10-39
Steering _________________________________________________________ 10-40
Manoeuvring and Docking __________________________________________ 10-41
Cruising _________________________________________________________ 10-44
Shallow Water Operation ___________________________________________ 10-44
Acceleration to High Speed _________________________________________ 10-45
Aerated Water ___________________________________________________ 10-46
Blockages (Debris in the Jet Unit)_____________________________________ 10-46
Operating With an Engine and Jet Unit Out of Service ____________________ 10-47
Shutting down the Jet Units after use _________________________________ 10-47
11 - Technical Drawings ___________________________________________ 11-1

Installation and Service Manual
Introduction
1 -Introduction
In This Section
Limited Warranty...................................................................................................................1-1
Warranty and Ownership Registration Form ........................................................................1-3
General Safety Notice............................................................................................................1-4
Limited Warranty
Terms of coverage
C.W.F. Hamilton & Co. Ltd. (Hamilton Jet) warrants to the original purchaser that each new Hamilton Jet
product is free from defects in material and workmanship under normal use and service for the warranty
period.
In the event that a warranted defect in material or workmanship is disclosed to Hamilton Jet within the
warranty period, Hamilton Jet's obligation is limited to, at its option, repairing or replacing the defective
product, or component part at its factory or such other location as may be designated by Hamilton Jet.
Defective products shall be returned to Hamilton Jet or its authorised service representative for
inspection with transportation charges prepaid by the purchaser to the location specified by Hamilton
Jet.
This warranty only applies where the product is shown, to the satisfaction of Hamilton Jet, to be
defective in material or workmanship during the warranty period.
Hamilton Jet will supply parts required for warranty repairs free of charge and pay reasonable authorised
labour costs.
To the extent permitted by law, this warranty sets out the original purchaser's exclusive remedies with
respect to the product covered by this warranty. In the event that Hamilton Jet determines it is unable to
repair or replace any component part(s) found to be defective in materials and/or workmanship,
Hamilton Jet's warranty liability shall be limited to payment by Hamilton Jet to the original purchaser of
an amount not to exceed the value of the defective part(s), together with shipping charges, if any,
incurred.
All products removed or replaced under the warranty shall become the property of Hamilton Jet.
All warranty claims shall be lodged with Hamilton Jet or its authorised distributor.
Warranty period
The warranty period for Hamilton Jet products is limited to a period of twenty-four (24) months from the
date of original shipment from the Hamilton Jet factory, or twelve (12) months from the vessel launch
date, whichever occurs first.
1-1

Introduction
Installation and Service Manual
Limitation of liability
This warranty is extended only to the original purchaser, and is not transferable to or assignable to any
other person or entity, and does not extend to future performance.
In no event will Hamilton Jet, its distributors, or affiliates be liable for any incidental, punitive or
consequential losses, inconveniences, damages or other costs resulting directly or indirectly from any
defect in the product covered by this warranty, including, but not limited to, loss of use, revenue or
profit.
Hamilton Jet reserves the right to change its product through changes in design or materials without
obligation to incorporate such changes in any products previously manufactured, but any improvement
or changes may be incorporated in replacement product.
Warranty does not extend to failures, damages or defects resulting from the following:
What Hamilton Jet determines to be, misuse, abuse, overloading, improper application, improper
transportation or storage, abnormal wear and tear, negligence, carelessness, accident, natural calamity,
vandalism, fouling caused by foreign material, peculiar water conditions or chemicals, or other
circumstances over which Hamilton Jet has no control.
Operation or maintenance in any way other than in accordance with the operating and maintenance
instructions of Hamilton Jet.
Vessel-to-shore electrical connections that change the corrosion potential of the vessel. For vessels
equipped with shore power this warranty will not extend to the product unless an isolating transformer
or galvanic isolator is fitted as described in the applicable Hamilton Jet Product Manual.
Incorrect installation, as per the applicable Hamilton Jet Product Manual and the applicable Hamilton Jet
Designer's Manual. This warranty will not extend to the product unless a negative earth bonding system
has been installed in the vessel as specified in the respective Hamilton Jet Product Manual, and a Jet
Mainshaft critical speed check carried out to Hamilton Jet's written satisfaction.
Warranty does not cover or provide payment or reimbursement for the following:
Any repairs or alterations carried out with the use of parts or accessories not manufactured by Hamilton
Jet or its authorised representatives.
Items incorporated in any Hamilton Jet product (other than by Hamilton Jet) when such items have been
manufactured by others or are warranted by their respective manufacturers in favour of the purchaser.
Used or reconditioned parts.
The cost of transporting the vessel to a repair facility and for all related towing, harbour, docking,
slippage, lifting, moorage, launching or retrieval charges.
Any product which may have been serviced, repaired or altered in any way by anyone other than
Hamilton Jet or a Hamilton Jet authorised facility.
No representations or express or implied warranty except as herein stated
To the extent permitted by law, this limited warranty is the only warranty extended by Hamilton Jet and
is in lieu of all other warranties, EXPRESSED or IMPLIED, oral or written and of all other obligations or
liabilities, including without limitation any IMPLIED WARRANTIES of MERCHANTABILITY or FITNESS for a
PARTICULAR PURPOSE. Except as provided in this warranty the product is sold as is, where is.
No other person or agent or distributor is authorised to modify this warranty, give any other warranty on
behalf of HamiltonJet or to assume for Hamilton Jet any other obligation or liability in connection with
the sale of its products.
In the United States and Canada, some states and provinces do not allow limitations on duration of an
implied warranty, or the exclusion or limitation of incidental or consequential damages, so the above
limitations or exclusions may not apply to you. This limited warranty gives you specific legal rights and
you may also have other rights, which vary from state to state.
In other countries outside the United States and Canada, you may have statutory rights which cannot be
affected or limited by the terms of this Warranty.
C.W.F. Hamilton & Co. Ltd. July 2005 [Rev H]
1-2

Installation and Service Manual
Introduction
Warranty and Ownership Registration Form
To allow Hamilton Jet to complete its records and in order to assist any claim under the attached limited
warranty, please complete this Warranty and Ownership Registration Form in full and return as soon as
possible by post, facsimile or Email to:
The Marketing Department, C.W.F. Hamilton & Co Ltd.
PO Box 709, Christchurch,
New Zealand.
Fax, [phone]
Email, [e-mail]
Hamilton Jet encourages the distributor to take responsibility for ensuring the purchaser and the distributor
complete this form at the time of sale and return it to Hamilton Jet. Please complete one form per vessel
only.
Jet Model
Serial Number(s)
Delivery Date
Commissioning / In service Date
Vessel/Project
Purchaser
Address
Contact Name
Signed
Distributor
Address
Contact Name
Signed
Office Use Only
Logged By
Project Code
Date
1-3

Introduction
Installation and Service Manual
General Safety Notice
Warning
A warning is an operation or maintenance procedure, practice, condition or statement which, if not strictly
observed, could result in injury or death to personnel.
This is indicated throughout this manual as shown below:
Caution:
A caution is an operation or maintenance procedure, practice condition or statement which, if not strictly
observed, could result in damage to, or destruction of equipment or loss of mission effectiveness.
This is indicated throughout this manual as shown below:
Note:
A note contains additional information that will help clarify a procedure.
This is indicated throughout this manual as shown below:
1-4

Installation and Service Manual
Product Description
2 -Product Description
In This Section
Introduction...........................................................................................................................2-1
Equipment Description..........................................................................................................2-2
Introduction
Waterjets have rapidly gained acceptance as the leading means of propulsion for all types of high speed
marine craft including ferries, work boats, patrol craft and pleasure boats.
Recent advances in waterjet technology have put them ahead of conventional propeller systems in both high
speed performance and reliability.
Conventional propeller powered craft have several shortcomings, such as vibration, higher engine loading
and susceptibility to damage from water borne debris.
Modern waterjet powered vessels offer many advantages:
High efficiency.
Rapid acceleration.
Shallow draft.
Manoeuvrability.
Smooth, quiet operation.
Lower maintenance.
Longer engine life.
Simplified installation.
No protrusions under the water.
Safety for personal working in the water near the vessel.
The waterjet unit is an ideal form of propulsion for vessels working in a marine mammal environment.
Hamilton Jet pioneered the commercial development of the modern waterjet system in the early 1950’s.
2-1

Product Description
Installation and Service Manual
Figure 1: Hamilton Quinnant Jet, Circa 1953
Today we have over 30,000 units in service world wide.
With a complete range of models suitable for power inputs of up to 10000kW per unit. Hamilton waterjets
are ideally suited to the efficient propulsion of a wide variety of high speed vessels, in either single or
multiple jet configurations.
Hamilton Jet is dedicated to the production of the highest quality waterjets and controls systems designed
and manufactured to meet the requirements of the worlds leading certifying authorities.
Full support for projects is provided by the global Hamilton Jet organisation through factory support staff,
regional offices and an extensive network of factory trained distributors in over 50 locations worldwide.
Equipment Description
The Hamilton HJ series is a range of highly efficient single stage waterjets suitable for propelling craft
typically up to 20meters in length and 30tonnes displacement, at speeds up to 50knots. HJ Series waterjets
are generally directly driven by high speed diesel engines.
The Hamilton HM & HT series are larger single stage waterjets suitable for vessels typically up to 65m in
length and are generally driven by high speed diesel engines via a reduction gearbox.
Mounted partly inboard at the stern of the vessel, the Hamilton waterjet consists of a totally integrated, jet
mounted hydraulic steering, reverse and control system package.
Water is drawn into the waterjet through an intake screen at the base of the intake, which is mounted flush
with the hull bottom. The pumping unit (impeller + stator) increases the pressure or "head" of the flow,
which is then discharged at high velocity at the nozzle. The reaction to this high velocity jet stream provides
the net thrust force, which is fully transmitted through the intake to the hull bottom.
A single piece balanced steering nozzle precisely directs the jet stream as commanded by the helm, providing
high turning forces to either port or starboard. An independent split-duct type reverse deflector, directs the
jet stream back underneath the hull to provide powerful astern thrust.
The reverse duct can be set to a "zero speed" position (where the ahead and astern thrusts are balanced) at
which point full steering is still available.
Infinitely variable forward and reverse thrust may be selected by varying the position of the reverse duct and
combined with the highly efficient steering, results in unparalleled vessel control and manoeuvrability.
2-2

Installation and Service Manual
Product Description
Main Components
Intake block
Is bolted or welded to the vessel hull.
Intake
Is bolted to the intake block and represents the main structural body of the jet unit. It is capable of
transmitting the full thrust of the jet unit to the hull bottom. The intake is cast from high silicon aluminium
alloy.
Thrust bearing
Mounted inside the bearing housing, absorbs the thrust generated by the impeller.
No external thrust bearing is required.
Water seal
Mounted on the mainshaft aft of the bearing housing. Stops water entering the bearing housing or the
vessel.
Coupling
The jet unit can be connected to various engine types using the following:
Close coupling to certain gasoline engines.
H-bar connection to the jet mainshaft splines.
Companion flange fitted to the jet mainshaft splines, where a longer driveshaft is required.
Engine mount and close coupling
This jet is designed with the option of a flexible close coupling arrangement combined with an engine mount.
This allows the engine to be moved as far aft as possible in the boat, simplifying the driveline arrangement
and providing a low noise torsionally flexible coupling.
Impeller
Mixed flow type, capable of pumping large volumes of water at relatively low pressures. Permits high
propulsive coefficients to be achieved at fast vessel speeds. The cast stainless steel impeller runs within a
replaceable stainless steel wear ring located in the rear section of the intake.
Tailpipe
The tailpipe contains a water lubricated bearing supporting the rear of the mainshaft.
The tailpipe contains a vaned stator to remove the rotation of the water flow, allowing a uniform axial
flow to the nozzle.
Steering nozzle
After the water flow passes through the impeller and stator, it is at a high pressure and relatively low
velocity.
Water flow at the nozzle outlet is at atmospheric pressure. This difference in flow pressure is converted
to flow velocity in the nozzle.
Correct nozzle sizing is critical to the correct operation of the jet unit.
2-3

Product Description
Installation and Service Manual
Steering assembly
Attached to the rear of the tailpipe, consists of a nozzle housing, nozzle insert and steering nozzle. The
steering nozzle is mounted inside the nozzle housing on vertical pivot pins and is rotated to port or starboard
by linkages attached to an inboard steering tiller. The nozzle insert ensures that the flow exiting the stator
section reaches the final steering nozzle outlet without being disturbed by the steering mechanism, thus
maximising steering efficiency.
Reverse duct
Can be positioned up or down by the reverse cylinder.
A splitter is incorporated into the reverse duct to divide and angle the astern jet stream downwards and
to the sides, clearing the transom and intake opening.
This stops recycling of water flow through the jet unit (which may be aerated or contain sediment) and
excessive disturbance to the bottom of the waterway.
Transom seal
Seals the hole in the transom through which the waterjet passes. It is bolted to the vessel transom and
incorporates a rubber ring which seals around the jet unit.
Reverse latch
The manually controlled reverse duct has a latch mechanism which locks the reverse duct in position. The
hand controller, automatically releases the brake when operated. The reverse duct cannot be moved by
hand from outside the boat, nor by the pressure of the water.
The latch has been factory set and should not require adjustment during installation.
Screen rake
May be fitted as an optional extra. The screen rake is a hand operated rake mounted in the lower half of the
intake, designed to clear any debris caught by the intake screen.
Dry run kit (optional extra)
The dry run kit is an optional extra that can be fitted to the jet unit at the customer's request.
It is purchased at additional cost and should be requested when the initial jet order is placed.
The dry run system is typically used for man-overboard boats and lifeboats where the engines need to be
started before the vessel is in the water.
The dry run kit consists of a special marine bearing which can be run dry for short periods of time. Standard
rubber marine bearings cannot be run dry.
Overflow preventer/hatch extension (optional extra)
The overflow preventer is an optional extra for use with jet units where the water level (when the vessel
is fully laden) is above the normal level of the main inspection cover.
It is attached to the top of the intake around the outside of the main inspection cover.
2-4

Installation and Service Manual
Product Description
Figure 2: Figure 1: HJ212 Main Components
1 Intake 7 Reverse duct
2 Intake block 8 Transom plate
3
Inspection hatch
9
Anode
4 Reverse assembly 10 Intake screen ( hidden)
5 Steering shaft 11 Hatch extension
6 Tail pipe
2-5

Product Description
Installation and Service Manual
2-6