Fast Ferry Powering and Propulsors – The Options
By Nigel Gee
Managing Director
Nigel Gee and Associates Ltd, UK
SUMMARY
In the 1970’s and 1980’s, fast ferries were used to transport passengers only and
most were propelled by a pair of industry standard 16 cylinder diesel engines each
driving a waterjet. The size of these vessels was mainly suitable for 300-400
passengers and with speeds of 35-45 knots. Today, passenger ferry sizes have
increased and speeds up to 60 knots are now possible. During the 1990’s in excess
of 100 fast car/passenger ferries have been introduced into service. The speed of
development possibilities for the future are to an extent governed by available prime
movers and propulsors. With increasing size and speed, high installed powers are
required and this has lead to multiple prime mover and propulsor installations.
This paper examines some of the engine and propulsor options open to designers,
builders, and operators, and shows how powering and propulsor choices have been
made through a number of case studies.
AUTHORS BIOGRAPHY
Having graduated with an Honours Degree in Naval Architecture from Newcastle
University in 1969 and, in the same year, completed a shipyard apprenticeship
sandwich course with Swan Hunter Shipbuilders in Newcastle, England, Nigel Gee
entered a career in the Naval Architecture of high speed and novel ship and boat
forms beginning with Burness Corlett & Partners, Consultants, in Hampshire,
England, moved to manufacturing industry with Hovermarine in 1971 being promoted
to Engineering Manager in 1976.
Left Hovermarine to pursue an academic career in 1979 as Senior Lecturer in Naval
Architecture and Fluid Mechanics at the Southampton Institute. Lectured to First
Degree level and undertook a number of research projects linked with industry.
In 1983 returned to industry with the Vosper Group as Technical General Manager of
a department with 60 technical personnel. Left in 1986 to start the design company
Nigel Gee and Associates Ltd.
Since 1986 the company has undertaken designs for over 120 built fast vessels.
These vessel designs range from 10m, 30 knot crew boats, to 200m, 25 knots fast
container ships. In the field of fast ferries, the company has produced designs for a
number of SES and catamaran designs including two 36 knot ferries introduced into
service in New York Harbour in 1997, and a 55 knot vessel which entered service in
1
Argentina in January 1999. A number of designs have been produced for fast car
and passenger ferries and fast freight vessels. Design is in progress for a fast car
ferry due for delivery in mid 2002 and ten vessels have been constructed to the
company’s design for a 25 knot fast feeder container vessel. Further designs for fast
freight vessels with speeds from 30-60 knots are in progress.
Nigel Gee is a Fellow of the Royal Institution of Naval Architects and a Member of the
Society of Naval Architects and Marine Engineers.
1.
ENGINE OPTIONS
Engine options for powering large fast passenger craft, or fast Ro-Pax craft
have been examined. Only engine powers in excess of 2000kW per single
engine have been considered. The high speed diesel engines, medium speed
diesel engines and gas turbine engines normally considered for fast ferry
powering are listed in Tables 1, 2 and 3. These are manufacturers data for dry
engines without gearbox. Footprint is calculated from the engine overall
length by overall width.
Specific Fuel Consumption’s (SFC’s) are
manufacturers quotations in ISO conditions.
Figure 1 shows the distribution of high speed and medium speed diesels and
gas turbines according to power ranges in steps of 2MW. It can be seen that
a range of high speed diesels are available to cover powers from 2-10MW with
the number of engine choices in each power band falling with increasing
power. Similarly, for medium speed diesels there is a wide range of engines
available up to 20MW, and then further single engines available up to a
maximum of 36MW. Multiple gas turbine choices are concentrated in the
range 2-6MW with individual engines covering a number of higher ranges.
There is a significant gap in the availability of gas turbines for powers from 814MW which is becoming an increasingly common fast ferry power demand.
It is of course possible to fulfil this demand by using multiple engines, albeit
with more complexity and possible use of heavy combining gearboxes.
Figures 2, 3 and 4 are plots of engine power to weight ratio for a range of
powers. Figure 2 shows all the diesel engines and Figure 3 the gas turbines.
Power to weight ratios are compared for diesels and gas turbines in Figure 4.
It can be seen that the power to weight ratio of the gas turbines is very
significantly higher than the diesels, generally ranging between 25 or 40 times
as high for gas turbines.
Similarly, Figures 5, 6 and 7 show power to footprint ratio, and once again the
gas turbine engines are superior, generally having power to footprint ratios
three to five times greater than those for diesels. Of course, footprint is not the
only consideration when looking at the volume requirements for engine rooms,
and the increased volume of intake and exhaust systems and intake air
filtration systems required for gas turbines, often means that there is little
difference in the volumetric requirements for gas turbine and high speed diesel
engines, particularly in smaller high speed passenger ferries.
2
In general, it can be stated that the weight of gas turbine installations will be
very significantly less than for diesel installations, and volumes may be less
particularly in larger power installations. On the basis of weights and volume
alone, gas turbines would be favoured.
Figure 8 shows a comparison between specific fuel consumption for the range
of gas turbines and diesels, and it can be seen that at any given power level
gas turbine SFC’s are higher than diesel SFC’s. Of course it is also true that
gas turbine installations require less power for a given vessel speed, because
of their lower weight contributing to a lower displacement for the vessel. If less
power is installed then there is an effective saving in SFC and this is shown in
Figure 8. Nevertheless, in general even this reduction in fuel consumption is
insufficient to offset the increased SFC of the gas turbine in most cases.
Table 4 shows some typical vessel displacements and machinery weights for
a range of vessels designed by Nigel Gee and Associates. In each case, the
percentage reduction in displacement which could be achieved by substituting
gas turbines for diesels is shown together with the percentage SFC increase.
In four of the five cases, the SFC increase more than offsets the displacement
reduction. In the case of the very large 40 knot ro-pax, there is a larger
displacement reduction than SFC increase. This particular vessel has an
installed power in excess of 100MW, which accounts for the large reduction in
weight and at this power, gas turbines fuel consumption is approaching that of
large diesel engines. These figures must be viewed with some caution since
the weight of the engine and gearbox only has been considered and not the
associated inlet and exhaust. Nevertheless, there is a clear indication that for
larger vessels the installation of large lightweight efficient gas turbines could
have advantages in fuel consumption as well as weight and volume.
A criterion often advanced for assisting in the choice between diesel and gas
turbine installation is that of range. Figure 9 shows the variation of speed with
range for a vessel fitted with alternative diesel or gas turbine installations of
the same power. Clearly, the gas turbine vessel will have a lower empty
weight and, therefore, a higher speed at low range. However, since the fuel
consumption is higher, then as range increases, the amount of fuel carried
increases to the point where at a certain range the gas turbine vessel is
actually heavier than the diesel vessel and its speed lower. The preliminary
conclusion would be that at up to the critical range the gas turbine installation
would be selected and above the critical range the diesel selected. However,
if the power of the diesels are increased to give the same empty speed, then
because the percent weight increase is normally less than percent SFC saving
the diesel vessel will show benefit throughout the range.
Weight, volume and SFC are of course only part of the story. Table 5 lists
other considerations which owners and operators will need to look at before
deciding on a particular engine installation. The figure is self-explanatory and
perhaps the main features are the purchase and maintenance costs and the
reliability, availability and maintainability of the chosen units. The case studies
in Section 3 of this paper show how these considerations often become
dominant in engine choice.
3
2.
PROPULSORS
Table 6 shows the propulsor options of fast ferries, together with an indication
of the maximum efficiency that might be expected, and some qualitative
descriptions of the potential advantages and disadvantages of a particular
propulsive device.
For most small vessels, the choice is between propeller or waterjet and the
selection will normally be made on the basis of speed. Vessels having a
speed capability over 35 knots are most likely to have waterjet propulsion
because high efficiencies are still possible. Propeller efficiencies at these
higher speeds are diminishing and propeller sizes may become
unmanageable on small lightweight high speed vessels. For very large
vessels electric podded propulsion is becoming a significant option.
3.
CASE STUDIES
Table 7 below lists six vessels designed by Nigel Gee and Associates which
are used to illustrate some of the criteria used in selecting prime movers and
propulsors for these vessels.
3.1
Case Study 1
This is a 30m, 45 knot passenger vessel (see Figure 10) currently at the
detailed design stage and due for delivery in 2002. The vessel is designed to
meet a requirement for a very small craft to achieve high speeds with a high
degree of passenger comfort when operating in sea state 3-4. To achieve the
speed and comfort required, it is necessary to “fly” the vessel on a
combination of foils and buoyant pods. The hull design of the vessel is based
on the NGA Patented Pentamaran form, with a combination pod and lifting
hydrofoils spanning the aft sponsons, and a T-Foil at the bow which also
contributes net lift to the system The main problem with such a vessel is the
high vertical distance between the prime mover and the propulsive device.
Choices for this application are either a propeller driven through a V box and
steeply angled shaft, a waterjet with a deep scoop, or a Z-drive. In this
particular case, the propeller solution was regarded as relatively high risk,
mainly from the point of view of the cavitation of a propeller running at 40-45
knots on a high angled shaft. Waterjets were rejected because of the lower
efficiency associated with lifting water from the intake scoop to the hullmounted waterjet, and the drag of the scoop itself. Because the power of this
vessel is quite low (approximately 2.3MW) an Ulstein Speed-Z unit was
chosen as the propulsor. These units have been fitted to a variety of high
speed craft including SES, catamarans and foil catamarans. The necessity to
keep weight to an absolute minimum and the very limited space involved in the
single slender hull led to a gas turbine being selected as the prime mover
despite the higher fuel consumption.
4
3.2
Case Study 2
This vessel is designed to carry 400 passenger at 40 knots in sea state 3 on a
30nm route. The design requirement and choices made are summarised in
Figure 11. For this vessel a number of powering options were considered,
three of which are shown in Figure 12. Speeds of between 40-45 knots were
considered. The final selection was for 2 x TF50 gas turbines driving
waterjets. It is interesting to note that a solution using four diesel engines
would have yielded a slightly higher speed at a lower overall fuel consumption,
but nevertheless the gas turbine solution was selected. The operator wished
to have the facility to run at 100% MCR reasonably frequently and also
preferred gas turbine maintenance routines.
3.3
Case Study 3
Figure 13 shows the prime mover and propulsor selection for a 55 knot
passenger vessel built during 1999 for Buquebus. Once again despite
superior fuel consumption figures for a diesel solution the operator selected
gas turbines. The decision was made on a complex mix of space, weight and
vessel trim considerations. When considering costs it is significant that this
operator’s major competition on routes across the River Plate are aircraft and,
therefore, fuel cost considerations may not be as significant on some other
routes.
3.4
Case Study 4
This vessel is shown in Figure 14 and is currently in detail design destined for
delivery in late 2002. The vessel carries 300 passengers and 40 cars and has
a maximum speed of 40 knots. Fuel economy was of paramount importance
on this vessel and four diesel engines were selected.
3.5
Case Study 5
This vessel is a 40 knot large ro-pax ferry and at the preliminary design stage
for a Mediterranean customer (see Figure 15). The vessel can carry 800
passengers and 200 cars at 40 knots. The prime mover selection on this
vessel is further complicated by the possibility of building the vessel is either
aluminium or steel. For the same speed and payload the aluminium hull/gas
turbine propelled vessel will have better fuel economy than a steel vessel fitted
with medium speed diesel engines. The potential operator for this vessel is
currently weighing the trade-off between better fuel economy and higher
purchase cost of the vessel.
5
3.6
Case Study 6
This vessel is certainly not fast having a top speed of 12 knots (see Figure 16).
It is included as a case study to illustrate another set of design drivers on
prime mover and propulsor selection. This ro-pax vessel is very small
(approximately 35m) it has to carry a high load of 16 cars or 2 x 38 tonne
articulated trucks at speeds of 12 knots in seas with a maximum wave height
of 5m. Installed power levels on the vessel are driven by the berthing
requirement in Beaufort 10 winds, rather than by the free-running speed of 12
knots. As well as a high power required for berthing, very high side thrusts are
required, which has led to the selection of azimuthing pods for main propulsion
and very large twin bow thrusters. The huge power range and high cyclic
loading demanded by frequent berthings and very short passage times has led
to the selection of diesel electric machinery. Small high speed diesel engines
were selected on space and cost grounds.
4.
CONCLUSION
This short paper and selection of case studies has indicated that prime mover
and propulsor selection is normally made on the basis of a wide range of
owner/operator requirements and rarely restricted to simple considerations of
weight, space and fuel consumption.
6
Table 1.- Engine Power Comparison Table – High Speed Diesel
o
(Ferry Rating; ISO Conditions: air & water temp. 25 C)
Power
Type
kW
MTU 16V 396 TE74L
Ruston 8RK270HF
Paxman Valenta CM 12V
Cummins-Wärtsilä CW170 16V
Ruston 6RK270
Paxman VP185 12V
MTU 16V 4000 M70
Cummins-Wärtsilä CW170 18V
Cummins-Wärtsilä CW200 12V
Paxman Valenta CM 16V
Ruston 8RK270
Ruston 12RK270HF
Paxman Valenta CM 18V
Cummins-Wärtsilä CW200 16V
Paxman VP185 18V
Cummins-Wärtsilä CW200 18V
Pielstick 12 PA6 STC
MTU 16V 595 TE70L
Ruston 16RK270HF
Ruston 12RK270
Pielstick 12 PA6 B STC
Ruston 20RK270HF
Pielstick 16 PA6 STC
MTU 16V 1163 TB73L
Ruston 12RK280
CAT 3616
MTU 20V 1163 TB73
Ruston 16RK270
Pielstick 16 PA6 B STC
MTU 20V 1163 TB73L
MTU 16V 8000 M70
Ruston 16RK280
MTU 16V 8000 M90
CAT 3618
Ruston 20RK270
Pielstick 20 PA6 B STC
MTU 20V 8000 M70
Ruston 20RK280
MTU 20V 8000 M90
2000
2020
2045
2080
2265
2300
2320
2340
2400
2725
3020
3030
3065
3200
3500
3600
3880
3925
4040
4530
4860
5050
5180
5200
5400
6000
6000
6040
6480
6500
6560
7200
7200
7200
7550
8100
8200
9000
9020
Weight
kg
(Dry)
6235
17500
8117
11350
13050
7460
7475
12500
14500
10220
17500
22000
11147
18000
10161
19000
23000
13000
27000
22000
26000
33500
32000
19500
30000
31000
22500
27000
34000
22900
37000
37000
37000
36000
33500
41000
43000
46000
43000
Footprint
2
m
(LxB)
6.15
5.96
3.33
5.17
5.33
4.93
6.79
5.53
6.75
4.23
5.96
7.82
4.70
8.30
5.51
8.85
11.11
5.96
9.29
7.82
13.64
11.57
13.55
8.39
7.82
8.31
10.06
9.29
15.87
10.06
14.15
9.29
14.15
10.87
11.57
21.01
16.29
11.57
16.29
Power/Wt
kW/kg
0.321
0.115
0.252
0.183
0.174
0.308
0.310
0.187
0.166
0.267
0.173
0.138
0.275
0.178
0.344
0.189
0.169
0.302
0.150
0.206
0.187
0.151
0.162
0.267
0.180
0.194
0.267
0.224
0.191
0.284
0.177
0.195
0.195
0.200
0.225
0.198
0.191
0.196
0.210
Power/Footp'nt
2
kW/m
325.2
338.9
613.7
402.3
425.2
466.4
341.7
423.1
355.5
644.3
506.7
387.5
652.4
385.4
635.5
406.6
349.2
658.6
435.0
579.3
356.2
436.4
382.2
619.7
690.5
722.4
596.3
650.4
408.4
646.0
463.7
775.3
508.9
662.2
652.4
385.4
503.3
777.7
553.6
SFC
gr/(kW.hr)
(ISO rating)
207
204
230
205
200
200
194
205
205
230
200
204
230
205
200
205
184
215
204
200
184
204
184
212
190
208
208
200
184
207
195
190
199
203
200
184
195
190
199
Table 2.- Engine Power Comparison Table – Medium Speed Diesel
(Ferry Rating; ISO Conditions: air & water temp. 25oC)
Type
Ruston 12RK215
Wärtsilä 32 6R
Wärtsilä 32 6L
Ruston 16RK215
Wärtsilä 32 8R
Wärtsilä 32 8L
Wärtsilä 32 9R
Wärtsilä 32 9L
CAT 3612
Wärtsilä 38 6L-B
Sulzer ZA40S 6L
Wärtsilä 26X 12V
Wärtsilä 32 12V-E
Wärtsilä 32 12V
Wärtsilä 38 8L-B
Sulzer ZA40S 8L
Wärtsilä 46 6L-C
Wärtsilä 26X 16V
Wärtsilä 38 9L-B
Wärtsilä 32 16V-E
Sulzer ZA40S 9L
Wärtsilä 26X 18V
Wärtsilä 32 16V
Wärtsilä 32 18V-E
Wärtsilä 32 18V
Wärtsilä 46 8L-C
Wärtsilä 38 12V-B
Pielstick 12 PC 2.6 B
Sulzer ZA40S 12V
Wärtsilä 46 9L-C
Wärtsilä 64 5L
Pielstick 14 PC 2.6 B
Sulzer ZA40S 14V
Wärtsilä 38 16V-B
Pielstick 16 PC 2.6 B
Sulzer ZA40S 16V
Wärtsilä 64 6L
Wärtsilä 46 12V-C
Wärtsilä 38 18V-B
Pielstick 10 PC4.2B
Sulzer ZA40S 18V
Wärtsilä 64 7L
Pielstick 20 PC 2.6 B
Pielstick 12 PC4.2B
Wärtsilä 64 8L
Wärtsilä 46 16V-C
Wärtsilä 64 9L
Wärtsilä 46 18V-C
Pielstick 16 PC4.2B
Wärtsilä 64 12V
Pielstick 18 PC4.2B
Pielstick 20 PC4.2B
Wärtsilä 64 16V
Wärtsilä 64 18V
Power
kW
2370
2460
2760
3160
3280
3680
3690
4140
4250
4350
4500
4800
4920
5520
5800
6000
6300
6400
6525
6560
6750
7200
7360
7380
8280
8400
8700
9000
9000
9450
10050
10500
10500
11600
12000
12000
12060
12600
13050
13250
13500
14070
15000
15900
16080
16800
18090
18900
21200
23280
24000
26500
31040
34920
Weight
kg
(Dry)
13500
42000
32000
17000
62000
42000
68000
48000
24700
50000
59000
29100
76000
55000
66000
78000
95000
33700
72000
93000
86000
36800
67000
100000
75000
121000
82000
93000
102000
137000
185000
105000
119000
107000
115000
132000
227000
165000
120000
200000
145000
240000
135000
240000
265000
225000
292000
250000
300000
428000
330000
350000
532000
550000
Footprint
m2
(LxB)
-
6.75
11.80
11.02
8.06
13.45
13.68
14.12
14.76
6.74
13.40
19.81
14.15
14.61
20.05
15.98
24.86
24.00
16.42
17.27
21.43
26.87
17.55
27.05
23.25
28.89
31.57
23.47
28.16
26.50
36.02
36.02
31.89
36.05
25.50
39.32
40.19
45.17
44.24
51.41
42.59
45.50
40.64
56.60
49.66
55.74
53.82
60.52
67.23
84.07
72.82
78.52
102.05
110.37
Power/Wt
kW/kg
0.176
0.059
0.086
0.186
0.053
0.088
0.054
0.086
0.172
0.087
0.076
0.165
0.065
0.100
0.088
0.077
0.066
0.190
0.091
0.071
0.078
0.196
0.110
0.074
0.110
0.069
0.106
0.097
0.088
0.069
0.054
0.100
0.088
0.108
0.104
0.091
0.053
0.076
0.109
0.066
0.093
0.059
0.111
0.066
0.061
0.075
0.062
0.076
0.071
0.054
0.073
0.076
0.058
0.063
Power/Footp'nt
kW/m2
-
351.1
208.5
250.4
391.9
243.9
269.0
261.4
280.4
630.8
324.7
227.2
339.3
336.8
275.2
363.0
241.4
262.5
389.9
377.9
306.1
251.3
410.3
272.1
317.4
286.6
266.1
370.7
319.6
339.6
262.4
279.0
329.3
291.2
470.6
305.2
300.1
279.0
295.0
257.7
317.0
309.2
369.1
280.9
323.8
301.4
336.1
312.3
315.3
276.9
329.6
337.5
304.2
316.4
SFC
gr/(kW.hr)
(ISO rating)
199
190
183
199
190
183
190
183
203
178
186
189
188
181
178
186
175
189
178
188
186
189
181
188
181
175
177
184
185
175
171
184
185
177
184
185
171
175
177
184
185
171
184
184
171
175
171
175
184
169
184
184
169
169
Table 3.- Engine Power Comparison Table - Gas Turbines
o
(ISO Conditions: 15 C, 1.013mbar, 60% relative humidity)
Type
Power
Weight
kW
kg
Footprint
2
(Ferry Rating)
2375
1740
m
(LxB)
1.40
Allied Signal TF40
2983
601
Pratt & Whitney ST30 Dry
3341
Allied Signal TF50A
Power/Weight
kW/kg
Power/Footprint
2
kW/m
SFC
gr/(kW.hr)
1.36
(ISO rating)
1696
270
1.27
4.96
2356
299
500
1.10
6.68
3027
263
4000
710
1.27
5.64
3159
277
Pratt & Whitney ST40 Dry
4039
500
1.10
8.08
3659
254
GE LM600
4474
612
1.95
7.31
2293
269
Solar Taurus 60M
5010
8499
6.19
0.59
809
266
Rolls-Royce 501-KF7
5235
1361
4.31
3.85
1216
265
Rolls-Royce 601-KF9
6469
1361
2.42
4.75
2671
252
Rolls-Royce 601-KF11
7830
1723
3.13
4.54
2504
248
GE LM1600
14318
3424
9.06
4.18
1581
231
ABB GT35
17000
23000
37.95
0.74
448
260
Rolls-Royce Spey
19500
25633
17.14
0.76
1138
226
GE LM2500
24609
4762
14.31
5.17
1720
226
GE LM2500+
30201
5079
14.96
5.95
2019
215
GE LM6000PC
42752
7302
18.51
5.86
2310
200
Rolls-Royce Trent
50000
25941
40.06
1.93
1248
203
Rolls Royce UT 903
Table 4.- Engine Weight & SFC Comparisons Involving NGA Designs
Diesel Full Load
Displacement
(tonnes)
Diesel Engine +
GB Weight
(tonnes)
GT Engine +
GB Weight
(tonnes)
% Displacement
Reduction
% SFC
Increase
35 knot Passenger
Ferry NYFF
155
16
7
6
30
55 knot Passenger
Ferry BUQUEBUS
205
50
15
17
30
40 knot Ro-Pax
PECAN (HSD)
2400
130
30
4
14
40 knot Ro-Pax
PECAN (MSD)
2500
252
30
9
20
40 knot Ro-Pax
SEABRIDGE
25000
2000
200
7
5
Ferry Type &
Application
Table 5. Other Considerations
•
Will Diesels Fit ?
Ø Small boats, high powers
Ø Slender craft
• Cost / kW
• Maintenance Costs
• Can A Lightweight Diesel Provide High Enough Power
Ø High speed diesel limit
Ø Medium speed diesel limit
Ø Gas turbine
• Reliability, Availability, Maintainability
• Frequency of Need To Use 100% MCR
10 MW
35 MW
50 MW
(90 MW Soon!)
Table 6.- Propulsor Options
Propulsor Type
Propeller
Preferred Speed
Range (knots)
Maximum
Efficiency
up to 35
0.73
- Low Cost
- High diameter
- Vulnerability
- High Cost
Advantages
Disadvantages
Waterjet
30-70
0.73
- Compact
- Low Vulnerability
- Steerable
Surface Propeller
40-100
0.67
- High Efficiency at very high
speeds
speeds
- Few commercially
provensystems
systems
proven
- High cost
Electric POD Drives
up to 30
0.75*
- Steerable
- Very high efficiency
- Flexibility for type alocation of
primemovers
movers
prime
Z-Drives
up to 45
0.75*
- High efficiency
- Deep shaft line
- Limited Power &
torque range
range
Torque
0.50
- For Hydrofoils and POD
supportedboats
boats(no
(nowater
water
supported
contactrequired)
required)
contact
- Low efficiency
- Noise
Airscrews
(*) Excludes Strut Drag
100
+
Table 7. Case Studies
1. 45 knot Small Passenger Vessel
2. 40 knot Passenger Vessel
3. 55 knot Passenger Vessel
4. 40 knot Ro-Pax Ferry
5. 40 knot Large Ro-Pax
6. Small Diesel - Electric Ro-Pax Vessel
Gas Turbines
Medium Speed
Diesel
High Speed
Diesel
Figure 1.- Marine Propulsion Engines For Fast Ferries – The Ranges
2-4
4-6
6-8
8-10
10-12
12-14
14-16
16-18
18-20
20-22
22-24
24-26
26-28
28-30
30-32
32-34
34-36
36-38
38-40
40-42
42-44
44-46
46-48
48-50
50-52
Power/Weight (kW/kg)
Figure 2.- Power/Weight Ratio As A Function of Power - Diesel
0.40
High Speed Diesels
0.35
0.30
0.25
0.20
Medium Speed Diesels
0.15
0.10
0.05
0.00
0
5000
10000
15000
20000
Power (kW)
25000
30000
35000
Figure 3.- Power/Weight Ratio As A Function of Power – Gas Turbine
9.00
Large scatter in data is caused by differences in the way
manufacturers quote gas turbine weight. Some include
acustic insulation, some others don't.
8.00
7.00
Power/Weight (kW/kg)
6.00
5.00
4.00
3.00
2.00
1.00
0.00
0
5000
10000
15000
20000
25000
Power (kW)
30000
35000
40000
45000
50000
Figure 4.- Comparison of Power/Weight Ratio Between Diesel And Gas Turbine
9.00
8.00
7.00
Power/Weight (kW/kg)
6.00
Diesel
Gas Turbine
5.00
4.00
3.00
2.00
1.00
0.00
0
5000
10000
15000
20000
25000
Power (kW)
30000
35000
40000
45000
50000
Figure 5.- Power/Footprint Ratio As A Function of Power - Diesel
900.00
800.00
700.00
Power/Footp'nt (kW/m2)
600.00
500.00
400.00
300.00
200.00
100.00
0.00
0
5000
10000
15000
20000
Power (kW)
25000
30000
35000
Figure 6.- Power/Footprint Ratio As A Function of Power – Gas Turbine
4000.00
Large scatter in data is caused by differences in the
way manufacturers quote gas turbine weight. Some
include acustic insulation, some others don't.
3500.00
Power/Footp'nt (kW/m2)
3000.00
2500.00
2000.00
1500.00
1000.00
500.00
0.00
0
5000
10000
15000
20000
25000
Power (kW)
30000
35000
40000
45000
50000
Figure 7.- Comparison of Power/Footprint Ratio Between Diesel And Gas Turbine
4000.00
3500.00
Power/Footp'nt (kW/m2)
3000.00
Diesel
Gas Turbine
2500.00
2000.00
1500.00
1000.00
500.00
0.00
0
5000
10000
15000
20000
25000
Power (kW)
30000
35000
40000
45000
50000
Figure 8. SFC Comparison Between Gas Turbine and Diesel
300
280
SFC (gr/(kW.hr))
260
Effective Reduction in SFC
by Weight and Power Saving
240
220
Gas Turbine
200
180
Diesel
160
0
10
20
30
40
50
60
Total Installed Power (MW)
70
80
90
100
Figure 9. Speed Variation With Range for Diesel and Gas Turbine
Same Installed Power
Diesel & Gas Turbines
Speed at Full Load Displacement
Normal expected range where % Wt increase < % SFC saving
Increased power Diesels where % Wt
increase < % SFC saving
DIESEL
Increased power Diesels where
% Wt increase > % SFC saving
GA
ST
UR
BI
NE
Range
Figure 10. Case Study 1 – 45 knot Small Passenger Vessel
• Design Requirement
Ø 149 passengers; 40/45 knots.
Sea state 4; High comfort level.
• Hull Form Selected
Ø Stabilised monohull (Pentamaran) with
submerged Pods.
Weight critical design.
• Power Required
Ø 2 / 2.5 MW.
Ø Gas turbine selected on weight and
space criteria.
• Propulsor
Ø Vessel ‘flies’, needs high vertical
separation between prime mover and
propulsor.
Waterjet and scoop or Z-Drive.
Z-Drive available and gives higher
efficiency
Designer’s Note: Limited range of Z-Drives or other propulsors available for this type of application
Figure 11. Case Study 2 – 40 knot Passenger Vessel
• Design Requirement
Ø 400 passengers - 40 knots
Ø Sea state 3
• Hull Form Selected
Ø Round bilge catamaran
• Power Required
Ø
Ø
Ø
Ø
• Operator Choice
Ø TF50 gas turbines
Ø Wants to run 100% MCR, often prefers
gas turbine maintenance routine
• Propulsor
7.2 MW (gas turbine)
8.1 MW (diesels)
Diesels 12½ % higher power
But gas turbines SFC 30% higher
Ø KaMeWa waterjets
Figure 12. Case Study 2; Power Requirements
16000
Power Required - 4 x MTU 16V4000
Power Required - 2 x TF50
14000
22 xx TF80
TF80 Turbines
Turbines
12000
Required Power (kW)
Power Required - 2 x TF80
10000
4 x MTU 16V4000
4 x MTU 16V4000
8000
22 xx TF50
TF50 Turbines
Turbines
6000
4000
2000
0
20
25
30
35
Vessel Speed (knots)
40
45
50
Figure 13. Case Study 3 – 55 knot Passenger Vessel
• Design Requirement
Ø 55 knot top speed
Ø 50 knot cruise at full load in
sea state 3
• Hull Form Selected
Ø Hard chine catamaran
• Power Required
Ø
Ø
Ø
Ø
• Operators Choice
Ø TF80 (2 x TF40) gas turbines
13.0 MW diesel
11.0 MW gas turbine
Diesels 18% higher power
But gas turbines SFC 30% higher
Ø Decision based on space weight and
trim considerations
Ø Hull form allows side-by-side
installation
• Propulsor
Ø MJP waterjets
Figure 14. Case Study 4 – 40 knot Ro-Pax Ferry
• Design Requirement
Ø 350 passengers and 40 cars;
40 knots
• Hull Form Selected
Ø Round bilged catamaran
• Power Required
Ø 9.0 MW diesel
Ø 7.5 MW gas turbine
• Operators Choice
Ø Diesel for fuel economy
Ø 4 x MTU 4000 M70
• Propulsor
Ø Waterjets
Figure 15. Case Study 5 – 40 knot Large Ro-Pax Ferry
• Design Requirement Ø 800 passengers and 200 cars;
40 knots
• Hull Form Selected
Ø Pentamaran
• Power Required
Ø Aluminium / gas turbine – 22 MW
Ø Aluminium / high speed diesel – 25 MW
Ø Steel / medium speed diesel – 28 MW
Ø Aluminium / gas turbine – 22% less
power
Ø Steel / medium speed diesel – 18%
less SFC
Ø Aluminium/gas turbines better fuel
economy - but higher cost
• Operators Choice
Ø Under discussion
• Propulsor
Ø Waterjet
Figure 16. Case Study 6 – Small Diesel-Electric Ro-Pax Vessel
• Design Requirement
Ø 16 cars or 2 x 38t articulated trucks
and 100 passengers; 12 knots
Maximum length 35m
Sea state 4/5; Beaufort 10
• Hull Form Selected
Ø Full form monohull
• Power Required
Ø 2.0 MW (docking condition)
Ø Steerable thrusters with very high
bow thrust requirement
Ø Diesel / electric solution
• Engines Selected
Ø High speed diesels - 3 installed,
2 running
• Propulsors Selected
Ø Aquamaster