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 8-14MW 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 (Ferry Rating; ISO Conditions: air & water temp. 25 o C) Power Weight Footprint Power/Wt Power/Footp'nt SFC Type kw kg m 2 kw/kg kw/m 2 gr/(kw.hr) (Dry) (LxB) (ISO rating) MTU 16V 396 TE74L 2000 6235 6.15 0.321 325.2 207 Ruston 8RK270HF 2020 17500 5.96 0.115 338.9 204 Paxman Valenta CM 12V 2045 8117 3.33 0.252 613.7 230 Cummins-Wärtsilä CW170 16V 2080 11350 5.17 0.183 402.3 205 Ruston 6RK270 2265 13050 5.33 0.174 425.2 200 Paxman VP185 12V 2300 7460 4.93 0.308 466.4 200 MTU 16V 4000 M70 2320 7475 6.79 0.310 341.7 194 Cummins-Wärtsilä CW170 18V 2340 12500 5.53 0.187 423.1 205 Cummins-Wärtsilä CW200 12V 2400 14500 6.75 0.166 355.5 205 Paxman Valenta CM 16V 2725 10220 4.23 0.267 644.3 230 Ruston 8RK270 3020 17500 5.96 0.173 506.7 200 Ruston 12RK270HF 3030 22000 7.82 0.138 387.5 204 Paxman Valenta CM 18V 3065 11147 4.70 0.275 652.4 230 Cummins-Wärtsilä CW200 16V 3200 18000 8.30 0.178 385.4 205 Paxman VP185 18V 3500 10161 5.51 0.344 635.5 200 Cummins-Wärtsilä CW200 18V 3600 19000 8.85 0.189 406.6 205 Pielstick 12 PA6 STC 3880 23000 11.11 0.169 349.2 184 MTU 16V 595 TE70L 3925 13000 5.96 0.302 658.6 215 Ruston 16RK270HF 4040 27000 9.29 0.150 435.0 204 Ruston 12RK270 4530 22000 7.82 0.206 579.3 200 Pielstick 12 PA6 B STC 4860 26000 13.64 0.187 356.2 184 Ruston 20RK270HF 5050 33500 11.57 0.151 436.4 204 Pielstick 16 PA6 STC 5180 32000 13.55 0.162 382.2 184 MTU 16V 1163 TB73L 5200 19500 8.39 0.267 619.7 212 Ruston 12RK280 5400 30000 7.82 0.180 690.5 190 CAT 3616 6000 31000 8.31 0.194 722.4 208 MTU 20V 1163 TB73 6000 22500 10.06 0.267 596.3 208 Ruston 16RK270 6040 27000 9.29 0.224 650.4 200 Pielstick 16 PA6 B STC 6480 34000 15.87 0.191 408.4 184 MTU 20V 1163 TB73L 6500 22900 10.06 0.284 646.0 207 MTU 16V 8000 M70 6560 37000 14.15 0.177 463.7 195 Ruston 16RK280 7200 37000 9.29 0.195 775.3 190 MTU 16V 8000 M90 7200 37000 14.15 0.195 508.9 199 CAT 3618 7200 36000 10.87 0.200 662.2 203 Ruston 20RK270 7550 33500 11.57 0.225 652.4 200 Pielstick 20 PA6 B STC 8100 41000 21.01 0.198 385.4 184 MTU 20V 8000 M70 8200 43000 16.29 0.191 503.3 195 Ruston 20RK280 9000 46000 11.57 0.196 777.7 190 MTU 20V 8000 M90 9020 43000 16.29 0.210 553.6 199
Table 2.- Engine Power Comparison Table Medium Speed Diesel (Ferry Rating; ISO Conditions: air & water temp. 25 o C) Power Weight Footprint Power/Wt Power/Footp'nt SFC Type kw kg m2 kw/kg kw/m2 gr/(kw.hr) (Dry) (LxB) (ISO rating) Ruston 12RK215 2370 13500 6.75 0.176 351.1 199 Wärtsilä 32 6R 2460 42000 11.80 0.059 208.5 190 Wärtsilä 32 6L 2760 32000 11.02 0.086 250.4 183 Ruston 16RK215 3160 17000 8.06 0.186 391.9 199 Wärtsilä 32 8R 3280 62000 13.45 0.053 243.9 190 Wärtsilä 32 8L 3680 42000 13.68 0.088 269.0 183 Wärtsilä 32 9R 3690 68000 14.12 0.054 261.4 190 Wärtsilä 32 9L 4140 48000 14.76 0.086 280.4 183 CAT 3612 4250 24700 6.74 0.172 630.8 203 Wärtsilä 38 6L-B 4350 50000 13.40 0.087 324.7 178 Sulzer ZA40S 6L 4500 59000 19.81 0.076 227.2 186 Wärtsilä 26X 12V 4800 29100 14.15 0.165 339.3 189 Wärtsilä 32 12V-E 4920 76000 14.61 0.065 336.8 188 Wärtsilä 32 12V 5520 55000 20.05 0.100 275.2 181 Wärtsilä 38 8L-B 5800 66000 15.98 0.088 363.0 178 Sulzer ZA40S 8L 6000 78000 24.86 0.077 241.4 186 Wärtsilä 46 6L-C 6300 95000 24.00 0.066 262.5 175 Wärtsilä 26X 16V 6400 33700 16.42 0.190 389.9 189 Wärtsilä 38 9L-B 6525 72000 17.27 0.091 377.9 178 Wärtsilä 32 16V-E 6560 93000 21.43 0.071 306.1 188 Sulzer ZA40S 9L 6750 86000 26.87 0.078 251.3 186 Wärtsilä 26X 18V 7200 36800 17.55 0.196 410.3 189 Wärtsilä 32 16V 7360 67000 27.05 0.110 272.1 181 Wärtsilä 32 18V-E 7380 100000 23.25 0.074 317.4 188 Wärtsilä 32 18V 8280 75000 28.89 0.110 286.6 181 Wärtsilä 46 8L-C 8400 121000 31.57 0.069 266.1 175 Wärtsilä 38 12V-B 8700 82000 23.47 0.106 370.7 177 Pielstick 12 PC 2.6 B 9000 93000 28.16 0.097 319.6 184 Sulzer ZA40S 12V 9000 102000 26.50 0.088 339.6 185 Wärtsilä 46 9L-C 9450 137000 36.02 0.069 262.4 175 Wärtsilä 64 5L 10050 185000 36.02 0.054 279.0 171 Pielstick 14 PC 2.6 B 10500 105000 31.89 0.100 329.3 184 Sulzer ZA40S 14V 10500 119000 36.05 0.088 291.2 185 Wärtsilä 38 16V-B 11600 107000-0.108-177 Pielstick 16 PC 2.6 B 12000 115000 25.50 0.104 470.6 184 Sulzer ZA40S 16V 12000 132000 39.32 0.091 305.2 185 Wärtsilä 64 6L 12060 227000 40.19 0.053 300.1 171 Wärtsilä 46 12V-C 12600 165000 45.17 0.076 279.0 175 Wärtsilä 38 18V-B 13050 120000 44.24 0.109 295.0 177 Pielstick 10 PC4.2B 13250 200000 51.41 0.066 257.7 184 Sulzer ZA40S 18V 13500 145000 42.59 0.093 317.0 185 Wärtsilä 64 7L 14070 240000 45.50 0.059 309.2 171 Pielstick 20 PC 2.6 B 15000 135000 40.64 0.111 369.1 184 Pielstick 12 PC4.2B 15900 240000 56.60 0.066 280.9 184 Wärtsilä 64 8L 16080 265000 49.66 0.061 323.8 171 Wärtsilä 46 16V-C 16800 225000 55.74 0.075 301.4 175 Wärtsilä 64 9L 18090 292000 53.82 0.062 336.1 171 Wärtsilä 46 18V-C 18900 250000 60.52 0.076 312.3 175 Pielstick 16 PC4.2B 21200 300000 67.23 0.071 315.3 184 Wärtsilä 64 12V 23280 428000 84.07 0.054 276.9 169 Pielstick 18 PC4.2B 24000 330000 72.82 0.073 329.6 184 Pielstick 20 PC4.2B 26500 350000 78.52 0.076 337.5 184 Wärtsilä 64 16V 31040 532000 102.05 0.058 304.2 169 Wärtsilä 64 18V 34920 550000 110.37 0.063 316.4 169
Table 3.- Engine Power Comparison Table - Gas Turbines (ISO Conditions: 15 o C, 1.013mbar, 60% relative humidity) Type Power Weight Footprint Power/Weight Power/Footprint SFC kw kg m 2 kw/kg kw/m 2 gr/(kw.hr) (Ferry Rating) (LxB) (ISO rating) Rolls Royce UT 903 2375 1740 1.40 1.36 1696 270 Allied Signal TF40 2983 601 1.27 4.96 2356 299 Pratt & Whitney ST30 Dry 3341 500 1.10 6.68 3027 263 Allied Signal TF50A 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
Table 4.- Engine Weight & SFC Comparisons Involving NGA Designs Ferry Type & Application 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
Table 5. Other Considerations Will Diesels Fit? Small boats, high powers Slender craft Cost / kw Maintenance Costs Can A Lightweight Diesel Provide High Enough Power High speed diesel limit 10 MW Medium speed diesel limit 35 MW Gas turbine 50 MW (90 MW Soon!) Reliability, Availability, Maintainability Frequency of Need To Use 100% MCR
Table 6.- Propulsor Options Propulsor Type Preferred Speed Range (knots) Maximum Efficiency Advantages Disadvantages Propeller up to 35 0.73 - Low Cost Waterjet 30-70 0.73 Surface Propeller 40-100 0.67 Electric POD Drives up to 30 0.75* - Compact - Low Vulnerability - Steerable - High Efficiency at very high speeds - Steerable - Very high efficiency - Flexibility for type alocation of prime movers - High diameter - Vulnerability - High Cost - Few commercially proven systems - High cost Z-Drives up to 45 0.75* Airscrews 100 + 0.50 - High efficiency - Deep shaft line - For Hydrofoils and POD supported boats (no water contact required) - Limited Power & Torque torque range - Low efficiency - Noise (*) Excludes Strut Drag
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
Figure 1.- Marine Propulsion Engines For Fast Ferries The Ranges Gas Turbines Medium Speed Diesel High Speed Diesel 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
Figure 2.- Power/Weight Ratio As A Function of Power - Diesel 0.40 0.35 High Speed Diesels 0.30 Power/Weight (kw/kg) 0.25 0.20 0.15 Medium Speed Diesels 0.10 0.05 0.00 0 5000 10000 15000 20000 25000 30000 35000 Power (kw)
Figure 3.- Power/Weight Ratio As A Function of Power Gas Turbine 9.00 8.00 7.00 Large scatter in data is caused by differences in the way manufacturers quote gas turbine weight. Some include acustic insulation, some others don't. 6.00 Power/Weight (kw/kg) 5.00 4.00 3.00 2.00 1.00 0.00 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 Power (kw)
Figure 4.- Comparison of Power/Weight Ratio Between Diesel And Gas Turbine 9.00 8.00 7.00 Power/Weight (kw/kg) 6.00 5.00 4.00 3.00 Diesel Gas Turbine 2.00 1.00 0.00 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 Power (kw)
Figure 5.- Power/Footprint Ratio As A Function of Power - Diesel 900.00 800.00 700.00 Power/Footp'nt (kw/m 2 ) 600.00 500.00 400.00 300.00 200.00 100.00 0.00 0 5000 10000 15000 20000 25000 30000 35000 Power (kw)
Figure 6.- Power/Footprint Ratio As A Function of Power Gas Turbine 4000.00 3500.00 Large scatter in data is caused by differences in the way manufacturers quote gas turbine weight. Some include acustic insulation, some others don't. 3000.00 Power/Footp'nt (kw/m 2 ) 2500.00 2000.00 1500.00 1000.00 500.00 0.00 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 Power (kw)
Figure 7.- Comparison of Power/Footprint Ratio Between Diesel And Gas Turbine 4000.00 3500.00 3000.00 Power/Footp'nt (kw/m 2 ) 2500.00 2000.00 1500.00 Diesel Gas Turbine 1000.00 500.00 0.00 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 Power (kw)
Figure 8. SFC Comparison Between Gas Turbine and Diesel 300 280 SFC (gr/(kw.hr)) 260 240 220 200 Effective Reduction in SFC by Weight and Power Saving Gas Turbine 180 160 Diesel 0 10 20 30 40 50 60 70 80 90 100 Total Installed Power (MW)
Figure 9. Speed Variation With Range for Diesel and Gas Turbine Same Installed Power Diesel & Gas Turbines Normal expected range where % Wt increase < % SFC saving Speed at Full Load Displacement Increased power Diesels where % Wt increase > % SFC saving Increased power Diesels where % Wt increase < % SFC saving GAS TURBINE DIESEL Range
Figure 10. Case Study 1 45 knot Small Passenger Vessel Design Requirement 149 passengers; 40/45 knots. Sea state 4; High comfort level. Hull Form Selected Stabilised monohull (Pentamaran) with submerged Pods. Weight critical design. Power Required 2 / 2.5 MW. Gas turbine selected on weight and space criteria. Propulsor 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 400 passengers - 40 knots Sea state 3 Hull Form Selected Round bilge catamaran Power Required 7.2 MW (gas turbine) 8.1 MW (diesels) Diesels 12½ % higher power But gas turbines SFC 30% higher Operator Choice TF50 gas turbines Wants to run 100% MCR, often prefers gas turbine maintenance routine Propulsor KaMeWa waterjets
Figure 12. Case Study 2; Power Requirements 16000 Power Required - 4 x MTU 16V4000 Power Required - 2 x TF80 14000 Power Required - 2 x TF50 12000 2 x TF80 Turbines Required Power (kw) 10000 8000 6000 4 x MTU MTU 16V4000 16V4000 2 x TF50 Turbines 4000 2000 0 20 25 30 35 40 45 50 Vessel Speed (knots)
Figure 13. Case Study 3 55 knot Passenger Vessel Design Requirement 55 knot top speed 50 knot cruise at full load in sea state 3 Hull Form Selected Hard chine catamaran Power Required 13.0 MW diesel 11.0 MW gas turbine Diesels 18% higher power But gas turbines SFC 30% higher Operators Choice Propulsor TF80 (2 x TF40) gas turbines Decision based on space weight and trim considerations Hull form allows side-by-side installation MJP waterjets
Figure 14. Case Study 4 40 knot Ro-Pax Ferry Design Requirement 350 passengers and 40 cars; 40 knots Hull Form Selected Round bilged catamaran Power Required 9.0 MW diesel 7.5 MW gas turbine Operators Choice Diesel for fuel economy 4 x MTU 4000 M70 Propulsor Waterjets
Figure 15. Case Study 5 40 knot Large Ro-Pax Ferry Design Requirement 800 passengers and 200 cars; 40 knots Hull Form Selected Pentamaran Power Required Aluminium / gas turbine 22 MW Aluminium / high speed diesel 25 MW Steel / medium speed diesel 28 MW Aluminium / gas turbine 22% less power Steel / medium speed diesel 18% less SFC Aluminium/gas turbines better fuel economy - but higher cost Operators Choice Under discussion Propulsor Waterjet
Figure 16. Case Study 6 Small Diesel-Electric Ro-Pax Vessel Design Requirement 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 Full form monohull Power Required 2.0 MW (docking condition) Steerable thrusters with very high bow thrust requirement Diesel / electric solution Engines Selected High speed diesels - 3 installed, 2 running Propulsors Selected Aquamaster