Wartsila O P Waterjets PG

7/29/2019 Wartsila O P Waterjets PG.

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WATERJET RANGE

With this guide it is possible to make a rst jet size

selection and to check weights & dimensions o

jets and possible subsystems. There are two main

waterjet executions available. The pre-assembled

waterjet range and the large jet range have identical

perormance properties, as indicated on page 5.

A pre-assembled and pre-aligned jet delivered

with waterjet inlet duct and skid or direct installation

in the ships hull. For the pre-assembled execution

all auxiliary systems, such as hydraulic systems and

coolers, are mounted on the assembly and piping

connections are made. These units are available up

to approx. 4500 kW and ft in a standard 20 or 40

oot sea container.

For large jets the inlet duct is designed by

Wrtsil and built by the shipyard as part o the ship

construction. Auxiliary systems or the large jet rangecan be selected with this guide, based on the vessel

design details. The largest waterjet in our order book

is a 26,000 kW LJX2180 unit. Our design capability

goes up to 50 MW.

WRTSIL AXIAL WATERJET SERIES

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WRTSIL AXIAL JET TECHNOLOGY

Wrtsil axial waterjets are a line o

single stage, compact high perormance

waterjets combining mixed ow

properties with an axial build. The result

is a much reduced vessel transom

occupation with highly increased waterjet

cavitation margins or optimum vessel

operating exibility. The reduced transom

occupation is achieved without reduction

o the inlet duct diameter or reduction

o the waterjet pump size in order to

maintain maximum eciency or lowest

uel burn.

AVERAGE 25% REDUCED

TRANSOM OCCUPATION

Jet sizes are indicated by the ront sidediameter o the impeller seat ring. Unlike

a non-axial design, the Wrtsil axial

design waterjet does not expand in radial

direction downstream. The ow through

the jets is directed through the pump

over the most ecient path, while at the

same time the transom mounting ange

diameter is reduced. This will allow much

easier tting o the jet in the available

space either in width or height. For naval

architects it will deliver the possibility to

apply a larger power density onto narrower

hulls or achieving top vessel perormance.

AVERAGE 10% HIGHER SHAFT SPEED

= 10% LESS TORQUE

Compared with non-axial designs, the

shat speed o the impeller is on average

10% higher whilst the impeller tip speed

is still lower. This is achieved by the

impeller shape creating a large amount

o blade surace area within small radialdimensions. The low impeller tip speeds

avoid sand erosion, making the axial jet

ideal or shallow water operations, such as

landing crat. At ull manoeuvring power


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INLS system or the US Navy equipped with custom designed jets or thrust in all

directions (360 revolving jet nozzle fitted)

Diameter used ortype designation

Diameter used ortype designation

the impeller tip speed is maximum 30 m/s.

The lower torque a direct result o the

higher shat speeds with low tip speeds

can yield both weight and cost savings or

couplings in intermediate shat lines, or

shats in general and gearboxes.

UP TO 10% LOWER WEIGHTThe reduced transom size not only results

in reduced dimensions, but also gives the

installation a substantially lower weight.

Combined with our welded jet construction

this permits urther weight optimizations

and savings that can be as high as 15%

compared to non-axial jet designs. Since

(waterjet) weight at the very end o the vessel

is usually dicult to compensate elsewhere

in the ship, jet weight savings can result inimproved trim o the vessel. Weight savings

also increase the payload within the same

vessel design.

LARGE MARGINS FOR OPERATING

FLEXIBILITY AND MANOEUVRING

The pump cavitation margins are increased by

at least 35%. Thanks to this larger cavitation

margin and the lower impeller tip speed,

more power can be allowed onto the pump

during manoeuvring, resulting in a 15% higher

manoeuvring thrust and aster response to

acceleration. Also more power will be available

to overcome changing operating conditions,

such as increased vessel resistance due to

shallow water efects. Furthermore, with the

additional cavitation margin, operation with

a reduced number o shat lines is possible

at higher loads o the remaining engines,

improving operating exibility.

BLACK SMOKE REDUCTIONMARGINAL INCREASE IN POWER

ABSORPTION AT MANOEUVRING

During manoeuvring the diesel engine operates

in its critical zone while in this area waterjets

tend to absorb increased power or lower

impeller speeds. The result can be a high

load or the engine, causing smoke and an

increased thermal load. Thanks to Wrtsil

axial jet series this unwanted increase in power

absorption is up to 70% lower than that o

competing non-axial designs.

DESIGN LAYOUTS

All jet designs are available in a steering/

reversing (SR), reversing only (R), steering

only (S) and booster execution (B). For jet

sizes in between approx. 10004500 kW,

pre-assembled easy to install packages (SRF

executions) are available. On request we ofer

solutions or special applications e.g. thrust

in all 360 directions. The key benets o the

axial technology are valid or all executions.

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Machinery controls box with actory

settings made ahead o sea-trials

Unique compact high perormance

steering & reversing assembly

Cylinders and thrust bearing inboard resulting

in ull absence o oil lubricated or oil containing

parts outboard o the vessel

All piping connected, just one cooling water

connection to be made by the shipyard

Weld-in skid manuactured in the

same material as the hull

Hull customised inlet duct in Wrtsil supply or

top perormance and shipyard risk reduction

PRE-ASSEMBLED WATERJET PACKAGES

THE WATERJET PUMP

For all Wrtsil waterjets large units or

pre-assembled units exactly the same pump

is used and the same hydrodynamic design

process is applied. Pump impeller, stator

section and shat are all manuactured o the

same high quality materials or continued top

perormance long ater Newbuild trials.

STANDARDISED BUT NOT COMPROMISED

HIGH PERFORMANCE WITHIN EASY REACH

Every Wrtsil pre-assembled waterjet

package delivers the customised perormance

o large jets into the market o pre-assembled

jet packages up to 4500 kW. The inlet duct

o the pre-assembled waterjet package is

optimized or hull shape & operational prole.

Modern and cost ecient manuacturing

techniques accurately transer theComputational Fluid Dynamics designed

shape rom the screen to the shop oor. Ater

construction the inlet duct is seamlessly

integrated in the waterjet assembly that is

shipped as one plug-and-play unit or instant

installation by the ship yard.

STEERING AND REVERSING

COMPACT AND FAST

In the market o pre-assembled waterjet

packages, the steering and reversing assembly

is unique in its shape and dimensions.

Deviating rom the market standard, our

assembly ts well within the waterjet stator

transom mounting ange, providing optimum

positioning o multiple jets in the available

transom width. Also the clearance required

above the jet is small and a (swimming)

platorm is easy positioned above the jets.

MAINTENANCE OPTIMIZED

All cylinders are positioned inboard as well

as the waterjet thrust bearing. Apart rom theoperating reliability delivered it also provides

easy access or maintenance without the need

or dry-docking. There are no oil lubricated or

oil containing parts outboard the transom.

QUALITY MATERIALS

FOR CONTINUED HIGH PERFORMANCE

High perormance is one o the key eatures

o the Wrtsil axial jet series. However,

an incorrect material selection can slowly

degrade the perormance o a waterjet in the

years ater sea trials. For that reason Wrtsil

avoided aluminium as construction material

or the waterjet stator bowl. The stator bowl

plays a very critical role in the jet eciency

and the stator blade prole must remain in

top condition as originally designed. It blocks

a slow eciency decrease over time as result

o stator blade ow sheering or unwanted

rotation o the ow. The Wrtsil stator bowl

is thereore constructed o a high grade

stainless steel as common or our large jet

series. In addition to better perormance, the

maintenance requirement o the high gradestainless steel stator is minimal.

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WRTSIL 15002180 SIZES

Vessel speed (knots)15 20 25 30 35 40 45

6000

8000

10 000

12 000

14 000

16 000

18 000

20 000

22 000

24 000

26 000

28 000

30 000

32 000

1500 size

1620 size

1750 size1880 size

2020 size

2180 size

Vessel speed (knots)

WRTSIL 450810 SIZES

15 20 25 30 35 40 4550010001500200025003000350040004500

450 size

510 size

570 size

640 size

720 size

810 size

450 size

510 size

W RTSIL 9101400 SIZES

Vessel speed (knots)15 20 25 30 35 40 45

2000

3000

4000

5000

6000

7000

8000

9000

10 000

11 000

12 000

13 000

14 000

910 size

1000 size

1100 size

1200 size

1300 size

1400 size

910 size

WATERJET SIZE SELECTIONThe graphs above indicate the jet size required based on the relation

between the engine power and the design speed o the vessel. For

instance a ship with our 1250 kW engines and a corresponding

vessel speed o 33 knots will need our 510 size waterjets. A ship

with a design speed o 40 knots at 1250 kW power can use 450 size

waterjets. The correct jet size is thus indicated by the line above the

intersection o the power and the corresponding vessel speed (see

examples in graphs above).

Please contact us or an optimized jet selection based on specifc

vessel design parameters and operating profle, or or details onwaterjets above 50 knots or 30 000 kW. DXF/DWG ormat general

arrangement drawings o the most oten used sizes are available.

DIMENSION TABLE FOR PRE-ASSEMBLED SRF PACKAGES

A

D

F

B

Waterjet size

510 570 640 720 810

A mm 1400(1500*)

1550(1700*)

1750(1900*)

1950(2100*)

2200(2400*)

B mm 1000 1100 1200 1350 1550

C mm 2300 2600 2800 3100 3600

D mm 3000 3400 3800 4200 4800

E mm 1100 1200 1400 1500 1700

F mm 510 570 640 720 810

Weight steering** kg 1450 1800 2450 3000 4000

Weight booster kg 1050 1300 1800 2250 3000

Entrained water l 400 600 800 1150 1650

* When in reverse. ** Without oil and entrained water.

C

E

AXIAL SERIES WATERJETS

Weight & dimensions o pre-assembled SRF waterjet packages

Waterjetsize

Outboardlength mm

Inboardlengthmm 1)

Transomfange

diametermm

Weightsteering kg

WeightBooster kg

910 2300 4050 1165 3200 2250

1000 2500 4400 1280 4200 2900

1100 2800 4750 1405 5300 3700

1200 3000 5300 1535 7350 5300

1300 3250 5650 1665 8950 6250

1400 3500 6050 1790 11 100 7700

1500 3750 6550 1920 14 250 10 050

1620 4050 7000 2075 17 250 12 000

1750 4350 7500 2240 21 200 15 050

1880 4650 8050 2405 28 950 20 600

2020 5000 8550 2585 34 350 24 150

Note1) Inboard length may vary depending on the optimized shape o the inlet duct.

Inboard lengthOutboard length

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LARGE WATERJETSSR-series. The most compact waterjet available or

large ast vessels

LARGE MARGINS

FOR OPERATING FLEXIBILITY

Our large axial jets have set a standard in the

past years. Introduced in 2006 and selected

or many leading large vessel applications,

such as the US Navy JHSV and LCS programs,

Incat catamarans, and leading superyacht

applications. In addition to our axial design a

non-axial design is also available or vessels

requiring extremely high speeds above 55

knots up to speeds above 70 knots.

The inormation on the ollowing pages is

or the large jet range only. Wrtsil pre-

assembled packages come ully assembled as

one package or direct installation in the ship(see page 5).

JET HYDRAULIC SYSTEMS

Each steering and reversing waterjet requires

a hydraulic power pack (HPP) or steering

control and reversing actions. Two stainless

steel hydraulic cylinders are used to pivot

the steering bucket port and starboard, and

one central hydraulic cylinder to activate

the reversing plate up and down. Hydraulic

cylinders are tted with integrated eedback

sensors linked to the electronic jet control

system or eedback and indication. The

control o each steering and reversing waterjet

installed is independent and ailure in one

hydraulic system will not afect the other jets.

STANDARD HYDRAULIC POWER PACK (HPP)

AND LUBRICATION OIL PACK (LOP)

The hydraulic power pack or control o jet

steering and jet reversing movements, and thelubrication unit or the waterjet thrust bearing,

are combined in a single tank with two

compartments or ecient installation at the

yard site. The hydraulic and lubrication loops

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are ully separated to avoid any contamination

between hydraulic and lubrication oil. The main

hydraulic pump o the standard HPP is driven

by a Power Take Of (PTO) rom the gearbox or

rom the engine. In addition, an electric driven

pump is installed on the oil tank. The electric

pump is used to control the jet movements

with a reduced capacity when the main PTO

pump is not available.

The hydraulic power pack is standard equipped

with:

z 1 x steel tank with two separatedcompartments, hydraulic and lubrication

z1 x startup backup, cooling pump, verticallymounted

z Double gear pump PGP511 seriesz E-motorz Bell-housing and exible coupling between

E-motor and gear pump

z 1 x steel maniold with valves/unctionsaccording to hydraulic diagram (next page)

z Load sense circuit or PTO pump andstartup ow control

z Filter by-pass alarmz Steering unction: 1 x proportional directional control valve 1 x ow/pressure compensator 2 x load holding valve

z Reverse unction: 1 x proportional directional control valve 1 x ow/pressure compensator 1 x load holding valve

z Flushing unction or PTO pump 1 x ushing connection with ow control

valvez 1 x oilsea water cooler with Thermo valvez 1 x return lter mounted on the tank-coverz 1 x temperature gaugez 1 x dip-stick

z 1 x Thermo switchz 2 x level switch; low and too lowz 1 x air breather with steel capz 1 x gate valvez 1 x drain valvez 1 x junction box and wiring to all

components

The lubrication section is standard equipped

with:

z 1 x line mounted medium pressure lterwith clogged lter alarm

z 1 x lter by-pass unction 2-way ball-valve with non-return valves or lter

exchangez 1 x oilsea water coolerz 1 x temperature gaugez 1 x dip-stickz 1 x pressure switchz 1 x pressure gaugez 1 x level switchz 1 x air breather with steel capz 1 x drain valvez 2 x diferential pressure switch

NOTE: INSTALLATION DISTANCESLong distances between HPP and waterjet and

between HPP and the PTO connection or the

hydraulic pump should be avoided. Pressure

losses will occur in the piping i connections

are too ar apart and the jet steering/reversing

perormance could deteriorate. Oil lled piping

running through the vessel over long distances

also increases installation weight. I such

distances cannot be avoided, we can supply

ull electric driven power packs with the pumpdirectly mounted on the HPP tank, eliminating

all pressure and suction piping between

pump and HPP. Please contact us or more

inormation.


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Forward thrust Reverse thrust

Zero thrust Steering

Standard power pack arrangement.

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DESIGN DATA FOR HYDRAULIC SYSTEM UNITS

Jetsize

Max.steerfow

l/min

Max.revfow

l/min

Max.

fowtotal1

l/min

Settlingtimesteer2

sec

Settlingtimerev3

sec

E-motorpower

kW

Coolcap.hydr

kW

Coolcap.lubr.

kW

910 21.17 18.91 40.08 8 8 3 5.12 5.35

1000 23.30 25.16 48.46 8 8 3 6.19 5.27

1100 25.60 35.71 61.31 8 8 4 7.83 5.27

1200 28.32 39.16 67.48 10 10 4 8.62 6.95

1300 37.70 42.39 80.09 10 10 5.5 10.23 6.94

1400 40.57 59.59 100.16 10 10 5.5 12.80 6.99

1500 52.39 63.94 116.32 10 10 7.5 14.86 9.08

1620 60.70 72.78 133.48 12 12 7.5 17.06 9.25

1750 65.58 97.08 162.55 12 12 11 20.78 9.51

1880 88.06 104.30 192.36 12 12 11 24.58 14.03

1) Max ow total represents the ow required or a combined steering and reversing demand thatresults in the settling times as given in the table. For a 1400 size jet the ow o 100.16 dm3/min willthus move the jet over the ull steering range and the ull reverse range in 10 seconds.2) Settling time steering time required or a ull 60 degree steering movement.3) Settling time reversing time required or a ull movement rom either ull ahead to ull astern or v.v.

Pumptype

Displ.cc/rev

Max.rpm

Max.press.

barRot Shat Flange Weightkg

US NAVY, LITTORAL COMBAT SHIPLCS-2 USS INDEPENDENCE

2 x LJ150E waterjets for the wing propulsion lines 2 x LJ160E waterjets for the centre propulsion lines

1 16.2 1800 280 CCW SAE-A 82-2 (A) 14

2 25.2 1800 280 CCW SAE-B 101-2 (B) 18

3 40.5 1800 280 CCW SAE-B 101-2 (B) 18

4 54 1800 280 CCW SAE-C 127-2 (C) 29

5 67.5 1800 280 CCW SAE-C 127-2 (C) 30

6 94.5 2300 320 CCW SAE-C-C 127-2 (C) 63

7 130.5 2200 320 CCW SAE-D 127-2 (C) 78

8 162 2200 350 CCW SAE F SAE 4 hole 90

9 243 1800 350 CCW SAE F SAE 4 hole 172

LOAD SENSE VARIABLE DISPLACEMENT not only higher eciency, but also lower seconds ater the command was given on the

PUMP FOR DIRECT MOUNTING ON THE vessel resistance due to the absence o bridge. With special, ast crash stop jets the

GEARBOX PTO underwater appendages like shats, rudders time to ull crash stop thrust can be shortened

The selection o a suitable gearbox PTO can be and shat struts. The absence o parts below to less than 3 seconds. The example to the

made with the tables above. For instance the the waterline also makes waterjets an ideal right illustrates the crash stop action o such

jet size that you have selected or your vessel solution or shallow water operation. an installation, redirecting more than 40.000

with the jet selection graphs on page 5 is a With excellent manoeuvrability at all vessel litres o 120 km/h sea water in an instant,

1400 size jet. The rst table above indicates speeds, waterjets deliver ast turn-around while the gas turbine driving the jet keeps

that the ow or a combined steering and times or all applications. With catamarans it turning at constant high load throughout the

reversing movement is 100.16 dm3/min in is usually possible to achieve pure sideways crash stop operation.

order to achieve settling times o 10 seconds. movement and 360 degree turning without a

I the engine runs at 600 rpm at idle, and bow thruster. HYBRID OR WARP SYSTEMS

the step up ratio o the PTO on the primary Unique to Wrtsil is the delivery o various

side o the gearbox is 1, then the pump FAST FERRY hybrid or Waterjet And Rened Propeller

capacity according to the second table above Waterjets developed ast together with the rise (WARP) systems. These systems combine

has to be 100,160/600 = 166.9 cc/rev o the ast erry industry. With jets delivered to controllable pitch propellers with a waterjet.

(size 9). I the step up ratio o the PTO at the all the main builders o car/pax erries, there is The benet is that the largest parts o the total

primary side o the gearbox is 2, then a pump a broad experience or these systems. installed vessel power can be absorbed by the

capacity o 83.47 cc/rev (size 6) is sufcient. waterjet. Despite the high amount o power

FAST NAVAL CRASH STOP SYSTEM the dimensions o the jet remain relativelyTYPICAL REFERENCES/APPLICATIONS Waterjets do not require reversal o the rotation small due to the high allowed power density

Waterjets propulsion is the most successul direction to generate astern thrust. A bucket compared to a propeller. With the jet taking

and ecient method o propulsion or high- redirects the ow rom the nozzle, generating most o the total vessel power, the propellers

speed applications. The advantages are ull astern thrust generally within 810 can remain small in diameter as well limiting

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Copyright Austal Australia 2009Incat 112 m ast erry equipped with our 1500SRi jets each driven by 9000 kW

Diesel engine (4 vessels delivered).

Hybrid or WARP system.

Crash stop action o LJ210E jet in a 86 m

corvette driven by one 20 MW gas turbine

and approx. 11,000 kW Diesel power.

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the drat o the vessel. The result is a very attractive

operational prole. The propellers are ully optimized

or lower cruising speeds delivering optimum

eciency with low noise and vibrations. At the

same time the combination o the waterjet and the

propellers still gives access to higher speeds when

required. Hybrid systems were delivered or various

yachts with total vessel power up to 32 MW and or

Navy vessels up to 28 MW.

SHOCK REQUIREMENTS

FOR JETS IN NAVAL USE

Several waterjet installations have been supplied

with shock requirements proven by calculations. The

main changes required in case o shock are shock

mounts or equipment such as the hydraulic power

packs and oil lubrications sets, and strengthening

o the thrust bearing. Due to the inboard position o

the bearing that is relatively easy. The housing o the

bearing standard o aluminium to minimize weight is replaced with a steel housing and i required the

bearing can be somewhat oversized. Please contact

us to learn the possibilities and required actions

based on your project details.


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Q&AAXIAL VS. NON AXIAL

WHAT IS THE DIFFERENCE BETWEEN AN

AXIAL AND NON-AXIAL WATERJET? The

waterjet principle (see also under jet working

principle) is based on a pump. Pump types can

be grouped rom pure axial to radial pumps.A pure axial pump will deliver a high ow at a

low pressure. A pure radial pump will generate

a low ow at a high pressure. For a high thrust

output a waterjet needs to generate both a

high ow through the jet system and a high

pressure, requiring a jet pump with so called

mixed ow properties. The unique eature o

the Wrtsil axial ow waterjet is that it has

the mixed ow properties required, but delivers

it in a pure axial geometry. This results in a

substantial advantage as the water ollows the

optimum ow path straight through the pump

instead o partly travelling in radial direction

beore exiting at the nozzle.

WHAT IS THE DISADVANTAGE/LIMITATION

OF AN AXIAL JET? Axial jets are primarily

ocused on applications with maximum speeds

up to 50 55 knots. Above that the axial jet

should not be used and a more radial shaped,

mixed ow pump will give better results (see

also section above). For these extremely high

speed applications, we ofer our E-series

waterjets.

WHAT ARE THE BENEFITS OF AN AXIAL

JET? Compact, high eciency, low weight,

more cavitation margin, higher shat speed

reducing torque, low orces transerred to the

ship construction.

HYDRAULIC SYSTEMS

WHAT IS THE DIFFERENCE BETWEENELECTRIC AND PTO DRIVEN POWERPACKS?

For an electrically driven powerpack all power

or displacing the oil volume is delivered by

an electric power source. The pump or a

PTO driven powerpack is driven by a Power

Take Of o the gearbox or engine. For such a

powerpack normally an electric backup rom an

electrically driven pump with reduced capacity

is installed (see page 6). The big advantage o

an electrically driven powerpack is the absenceo long suction and pressure lines between the

pump and the oil tank, since the ull electric

driven pump is mounted directly on top o

the tank. This decreases installation work

and minimizes pressure losses in suction and

pressure lines. Further a ull electrically driven

powerpack is independent rom the engine

speed. At low speed and idle maneuvering

conditions the available speed rom the engine

or driving the HPP PTO pump is low, while

the request or hydraulic power during vessel

maneuvering is high. An electrically driven

pump is thus smaller in size than a PTO driven

pump.

DO PTO POWERPACKS HAVE A BACKUP

FACILITY? Yes, on a HPP with a PTO (Power

Take Of) driven pump a second electrically

driven pump is mounted directly on the HPP

oil tank. However, the backup has a limited

capacity (see page 7). This means that

response times will be lower in HPP backup

mode.

CAN THE POWERPACK BE PLACED IN

ANY LOCATION? It is advised to place the

powerpack as close as possible to the jet

steering assembly, as that is the location

where the hydraulic power has to be delivered.

In case o a powerpack with a PTO driven

pump the distance to the PTO also has to be

taken into account, to avoid too high losses in

piping to that end.

CAN THE PTO BE PLACED IN ANYLOCATION? The PTO driving the hydraulic

pump is normally placed on the primary side

o the gearbox. In this case it is possible to

put the jets into zero thrust position while

the engine is running, beore jet clutch in.

Placement on the secondary side is possible,

but electric power will have to be available to

control the jet beore clutch in with an electric

backup motor.

WILL THE POWERPACK STILL WORK IFTHE ENGINE ROOM IS FLOODED? Standard

powerpacks will malunction due to water

ingress through the breather and other

parts. To avoid malunction due to ooding

o compartments it is advised to place the

powerpack one deck above compartments

that can possibly be ooded in emergency

situations. Measures can be taken to avoid

malunction due to ooding, but the costs

depending on the exact demands are high

without exception.

WHAT DETERMINES THE DIMENSIONS OF

THE POWERPACK? Jet size, required settling

times and maximum roll o the vessel.

WHAT IS THE ADVANTAGE OF INBOARD

HYDRAULICS? An inboard hydraulic system

brings all hydraulic cylinders and hoses inboard

o the vessel in the jet room. This reduces

maintenance in general, especially when the risk

or marine growth is high. Specic advantages

are operation in ice conditions or waters with

high debris content. Furthermore, vulnerablemarine environments can benet as there are no

systems containing oil outboard the transom in

combination with our inboard thrust bearing and

outboard water lubricated bearing.

JET ENGINE MATCHING

CAN YOU ADJUST THE WATERJET SHAFT

SPEED TO SUIT A GEAR RATIO? Yes, by

varying the jet size or a constant engine power.

However, by purely selecting the jet size to suit

a gear ratio, the jet will become larger than

strictly required or your operation. The gearbox

manuacturer should thus ofer suitable gear

ratios to ensure the best perormance o the

waterjet system.

DOES WRTSIL DETERMINE THE GEAR

RATIO? With the engine perormance diagram,

Wrtsil selects the best ratio out o the gear

ratios ofered by the gearbox manuacturer.

In case a proper ratio is not available, a

diferent gearbox has to be selected to avoid

underperormance o the waterjet.

WHAT HAPPENS IF THE JET AND ENGINE

ARE NOT PROPERLY MATCHED? I the gear

reduction ratio is too low the waterjet will rotate

aster than optimal, delivering more thrust but

possibly overloading the engine. I the reduction

ratio is too high, the jet will not turn ast enough

and underperorm.

IS SEA MARGIN REQUIRED FOR A JET? No,

sea margin is not required. Compared to a xed

pitch propeller there are two main diferences.

Because o the jet inlet duct the jet impeller is

not directly inside the hull wake ow and the jet

impeller operates in a protected environment

created by the Wrtsil designed inlet duct.

Further, in deviation with an FPP, a jet is a pump,

and thus a diferent type o machinery (turbo

machinery) with a relatively at power absorption

curve is required.

WHAT IS THE SHAFT SPEED OF A WATERJET?

The shat speed depends on the jet size and the

power applied. A small jet at high power can run

at 2000 rpm, a large one at 200 rpm.

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WHAT IS THE STANDARD DIRECTION OF

ROTATION FOR A JET? Clockwise when acing

orward rom at. A diferent direction is possible,

but is considered a custom design with longer

delivery time and higher initial costs.

JET MAINTENANCE

CAN YOU DESCRIBE THE MAINTENANCE

REQUIRED FOR A WATERJET? We ofer

standard maintenance packages or every

mechanical job on the waterjet. The standard

packages contain all parts and consumables

required or a particular job. Standard

maintenance intervals are every 2.5 years and

every 5 years. Five years is normally a class

required docking interval. Maintenance strongly

depends on the intensity o the service and

local conditions.

JET OFFER

WHAT INFORMATION DOES WRTSIL NEED

FOR MAKING A WATERJET SELECTION

AND OFFER? As a minimum the waterline

length o the hull, the number o shat lines

and the relation between the ship design

speed and the engine power; e.g. 40 knots

at 4 x 7200 kW with a waterline length o

75 meter. I the relation o speed and engine

power is not known, we can make a rough

estimate based on the displacement o the

vessel. Additional inormation useul to urther

sharpen the jet selection is ull resistance data

o the hull including various displacements, the

ship operating prole and any specic design

requirements.

WHY USE WATERJETS?

HOW DO I KNOW IF I SHOULD USE

WATERJETS OR PROPELLERS? That should

be investigated case by case. In generalwaterjets are not used or ships with design

speeds below 30 knots, unless the vessel

is in special service, such as shallow water

operation.

The advantage o jets over propellers is their

ability to absorb high input powers on a small

diameter, reducing the size o the installation.

Further, the steering is integrated in the

jets and rudders are thus not required. The

absence o rudders and other appendages,such as shat struts, will substantially reduce

the resistance o the hull at high speed. Other

reasons or using waterjets can be shallow

water access, as the jet unit sits above the

vessel baseline in the transom, reducing vessel

drat and avoiding damage rom grounding.

Good maneuverability can also be a reason to

select jets as propulsion units. There is always

a relatively high ow leaving the jet nozzle at

both high and low vessel speeds.

FOR WHICH APPLICATIONS HAS WRTSIL

DELIVERED WATERJETS? For everything

rom slow 10 knot applications requiring

high maneuverability to high speed and high

powered 70 knot applications. Further several

hybrid (see also next question) solutions, as

well as various custom solutions or special

vessels, have been delivered.

CAN WATERJETS AND PROPELLERS BE

COMBINED? is possible or some applications,

Wrtsil calls that the Waterjet And Rened

Propeller (WARP) systems. Usually these

applications have top design speeds around

30 knots and an operating prole requiring

requent operation around 20 knots and

occasional operation around 30 knots. These

systems with two wing propellers and a central

booster jet operate on propellers only or the

speed around 20 knots, and on combined

propellers and jet or reaching the top speed.The main advantage is smaller propellers

than on an all propeller 30 knots ship, as

the propellers are optimized or the power

requirements around 20 knots. These hybrid

systems can thus be very attractive as they

combine the best o both worlds or ships

around 30 knots.

JET OPERATION

WILL THE JET START ITSELF? This dependson shat height and ship speed. At a ship

speed o 0 knots and with the waterline not

lower than on or just below the jet shat centre

line, the jet will always start (prime) at normal

idle engine speed. I the water level drops ar

below the impeller shat, priming will slowly

become more dicult and higher starting shat

speeds will be required or priming the pump.

When the ship makes speed, starting inactive

jet propulsion line will become easier even i

the waterline is ar below the jet impeller shat.

Due to the ship speed water will be orced into

the jet inlet duct.

>Idle

Above idle

High rpm

PRIMING, WATER COVERAGE

11


12/14

Several customers have recognized us as

their preerred service supplier to ensure the

availability and cost-ecient operation o their

installations. They benet rom having their

entire power system ully serviced by one

global supplier. Wrtsil Services provides ull

service throughout the product liecycle or

both marine and power plant customers, and is

constantly developing its network worldwide.

Additionally, we are continually

broadening our range o services by adding

valuable products and specialist services

to our portolio. In this way we also support

equipment onboard your vessel or at your

installation and in our numerous workshops

around the globe and in key ports, regardless

o your equipment make.

We oer liecycle efciency solutions in the

ollowing services product lines:

z Engine Servicesz

Propulsion Servicesz Electrical & Automation Servicesz Boiler Servicesz Operations & Management Servicesz Training Servicesz Environmental Services

These services cover everything rom

basic support with parts, eld service and

technical support to service agreements

and condition based maintenance; rom

installation and commissioning, perormance

optimization, including upgrades and

conversions, to environmental solutions,

technical inormation and online support.

The choice available to you extends rom

parts and maintenance services to a variety

o comprehensive, customized long-term

service agreements, including perormance

and operations & management agreements.

Our Services organization currently eatures

more than 11,000 dedicated proessionals

in 70 countries.

Wrtsil adds value to your business

at every stage in the liecycle o your

installations. With us as your service partner,

you receive many measurable benefts such

as availability and perormance, productivitygains and cost benefts. Above all, peace o

mind in the knowledge that your installation

is being serviced by the most experienced

partner you could have Wrtsil.

SERVICES


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SUPPORTFROM YOURLOCAL OFFICE

For a nal jet selection you are alwayswelcome to consult a local Wrtsil oce. In

cooperation with the centre o excellence or jet

propulsion they will optimize the selection and

jet perormance based on the requirements o

your ship design, hull parameters and/or ship

operating prole.

The addresses o our local oces worldwide

can be ound on www.wartsila.com,

or you can contact one o the below oces or

specic applications.

Wrtsil-Lips Inc.

3617 Koppens Way

Chesapeake Virginia 23323, USA

Tel. +1 757 558 3625

Wrtsil Deence

3 Boulevard de La Loire

Nantes 44275, France

Tel. +33 240 411 602

Wrtsil NetherlandsLipsstraat 52

5151RP Drunen, The Netherlands

Tel. +31 416 388 208


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WRTSIL is a registered trademark. Copyright 2011 Wrtsil Corporation.

Wrtsil is a global leader in complete liecycle power solutions or the

marine and energy markets. By emphasising technological innovation

and total efciency, Wrtsil maximises the environmental and economic

perormance o the vessels and power plants o its customers. Wrtsil

is listed on the NASDAQ OMX Helsinki, Finland.

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Documents

Wartsila O P Waterjets PG