Propulsion of VLCC

Contents

Introduction .................................................................................................5

EEDI and Major Ship and Main Engine Parameters........................................6

Energy Efficiency Design Index (EEDI) ......................................................6

Major propeller and engine parameters ....................................................7

320,000 dwt VLCC .................................................................................8

Main Engine Operating Costs – 16.3 knots ...................................................9

Fuel consumption and EEDI ....................................................................9

Operating costs .................................................................................... 12

Main Engine Operating Costs – 15.5 knots ................................................. 13

Fuel consumption and EEDI .................................................................. 13

Operating costs .................................................................................... 16

Summary ................................................................................................... 17

Propulsion of VLCC

Introduction

The size of Very Large Crude Carriers,

VLCCs, see Fig. 1, is normally within

the deadweight range of 250,000-

320,000 dwt and the ship’s overall

length is about 330-335 m.

Recent development steps have made

it possible to offer solutions which will

enable significantly lower transporta-

tion costs for VLCCs as outlined in the

following.

One of the goals in the marine industry

today is to reduce the impact of CO2

emissions from ships and, therefore,

to reduce the fuel consumption for the

propulsion of ships to the widest pos-

sible extent at any load.

This also means that the inherent de-

sign CO2 index of a new ship, the so-

called Energy Efficiency Design Index

(EEDI), will be reduced. Based on an

average reference CO2 emission from

existing tankers, the CO2 emission from

new tankers in gram per dwt per nauti-

cal mile must be equal to or lower than

the reference emission figures valid for

the specific tanker.

This drive may often result in opera-

tion at lower than normal service ship

speeds compared to earlier, resulting

in reduced propulsion power utilisa-

tion. The design ship speed at Normal

Continuous Rating (NCR), including

15% sea margin, used to be as high as

16.0-16.5 knots. Today, the ship speed

may be expected to be lower, possibly

15.5 knots, or even lower. However, so

far only few, if any, have specified lower

installed power for new VLCCs.

A more technically advanced develop-

ment drive is to optimise the aftbody

and hull lines of the ship – including

bulbous bow, also considering opera-

tion in ballast condition – making it pos-

sible to install propellers with a larger

propeller diameter and, thereby, ob-

Fig. 1: A VLCC

5Propulsion of VLCC

taining higher propeller efficiency, but

at a reduced optimum propeller speed.

As the two-stroke main engine is direct-

ly coupled with the propeller, the intro-

duction of the ‘Green’ ultra long stroke

G80ME-C engine with even lower than

usual shaft speed will meet this drive

and target goal. The main dimensions

for this engine type, and for other exist-

ing VLCC engines, are shown in Fig. 2.

Based on a case study of a 320,000

dwt VLCC, this paper shows the in-

fluence on fuel consumption when

choosing the new G80ME-C engine

compared with existing VLCC engines.

The layout ranges of 6 and 7G80ME-

C9.2 engines compared with existing

engines are shown in Fig. 3.

EEDI and Major Ship and Main Engine ParametersEnergy Efficiency Design Index (EEDI)

The Energy Efficiency Design Index

(EEDI) is conceived as a future manda-

tory instrument to be calculated and

made as available information for new

ships. EEDI represents the amount of

CO2 in gram emitted when transporting

one deadweight tonnage of cargo one

nautical mile.

For tankers, the EEDI value is essen-

tially calculated on the basis of maxi-

mum cargo capacity, propulsion power,

ship speed, SFOC and fuel type. How-

ever, certain correction factors are ap-

plicable, e.g. for installed Waste Heat

Recovery systems. To evaluate the

achieved EEDI, a reference value for

S90ME-C8.2G80ME-C9.2S80ME-C8.2

13,8

8914,8

79

14,0

71

13,5

86

1,89

0

2,84

0

3,01

0

2,83

5

1,80

0

5,680 5,0005,3745,020

1,96

0

1,73

6

2,65

6

S80ME-C9.2

Fig. 2: Main dimensions for a G80ME-C9.2 engine and for other existing VLCC engines

the specific ship type and the specified

cargo capacity is used for comparison.

The main engine’s 75% SMCR (Speci-

fied Maximum Continuous Rating) fig-

ure is as standard applied in the calcu-

lation of the EEDI figure, in which also

the CO2 emission from the auxiliary en-

gines of the ship is included.

According to the rules finally decided

on 15 July 2011, the EEDI of a new ship

is reduced to a certain factor compared

to a reference value. Thus, a ship built

after 2025 is required to have a 30%

lower EEDI than the reference figure.

6 Propulsion of VLCC

7S80ME-C9.2

6S90ME-C8.2

6S90ME-C7.1

6S80ME-C9.27G80ME-C9.2

6G80ME-C9.2

320,000 dwt VLCCIncreased propeller diameterG80ME-C9.2

4-bladed FP-propellersconstant ship speed coefficient ∝ = 0.28

SMCR power and speed are inclusive of: 15% sea margin 10% engine margin 5% light running

Tdes = 21.0 m

PossibleDprop = 11.0 m(=52.4% Tdes)

PossibleDprop = 10.5 m(=50.0% Tdes)

ExistingDprop = 9.5 m(=45.2% Tdes)

16.0 kn

M4

M4’

M1, M2

M1’M2’

M3

M3’

16.5 kn16.3 kn

15.5 kn

15.0 kn

72 r/min

78r/min

76r/min

G80ME-C9.2Bore = 800 mmStroke = 3,720 mmVpist = 8.43 m/s (8.93 m/s)S/B = 4.65MEP = 21 barL1 = 4,450 kW/cyl. at 68 r/min(L1 = 4,710 kW/cyl. at 72 r/min)

M = SMCR (16.3 kn)M1 = 31,570 kW x 78.0 r/min 7S80ME-C9.2M2 = 31,570 kW x 78.0 r/min 6S90ME-C8.2 M3 = 30,380 kW x 68.0 r/min 7G80ME-C9.2M4 = 30,090 kW x 65.7 r/min 7G80ME-C9.2

M’ = SMCR (15.5 kn)M1’ = 27,060 kW x 78.0 r/min 6S80ME-C9.2M2’ = 26,860 kW x 76.0 r/min 6S90ME-C7.1 M3’ = 26,040 kW x 68.0 r/min 6G80ME-C9.2M4’ = 25,370 kW x 62.0 r/min 7G80ME-C9.2

14.0 kn

ExistingDprop = 10.0 m(=47.6% Tdes)

∝

∝

∝

∝

∝∝

10,000

15,000

20,000

25,000

30,000

35,000

40 50 60 70 80 90 r/minEngine/propeller speed at SMCR

PropulsionSMCR powerkW

Fig. 3: Different main engine and propeller layouts and SMCR possibilities (M1, M2, M3, M4 for 16.3 knots and M1’, M2’, M3’, M4’ for 15.5 knots) for a

320,000 dwt VLCC operating at 16.3 knots and 15.5 knots, respectively.

Major propeller and engine parameters

In general, the larger the propeller diame-

ter, the higher the propeller efficiency and

the lower the optimum propeller speed

referring to an optimum ratio of the pro-

peller pitch and propeller diameter.

When increasing the propeller pitch for

a given propeller diameter with optimum

pitch/diameter ratio, the correspond-

ing propeller speed may be reduced

and the efficiency will also be slightly

reduced, of course depending on the

degree of the changed pitch. The same

is valid for a reduced pitch, but here the

propeller speed may increase.

The efficiency of a two-stroke main en-

gine particularly depends on the ratio of

the maximum (firing) pressure and the

mean effective pressure. The higher the

ratio, the higher the engine efficiency,

i.e. the lower the Specific Fuel Oil Con-

sumption (SFOC).

Furthermore, the higher the stroke/bore

ratio of a two-stroke engine, the high-

er the engine efficiency. This means,

for example, that an ultra long stroke

engine type, as the G80ME-C9, may

have a higher efficiency compared with

a shorter stroke engine type, like a

K80ME-C9.

Furthermore, the application of new

propeller design technologies, NPT

propellers, motivates use of main en-

gines with lower rpm. Thus, for the

same propeller diameter, these propel-

ler types are claimed to have an about

6% improved overall efficiency gain at

about 10% lower propeller speed.

Hence, the advantage of the new lower

speed engines can be utilised also in

case a correspondingly larger propeller

cannot be accumulated.

7Propulsion of VLCC

320,000 dwt VLCC

For a 320,000 dwt VLCC tanker, the

following case study illustrates the po-

tential for reducing fuel consumption by

increasing the propeller diameter and

introducing the G80ME-C9.2 as main

engine. The ship particulars assumed

are as follows:

Scantling draught m 22.5

Design draught m 21.0

Length overall m 333.0

Length between pp m 319.0

Breadth m 60.0

Sea margin % 15

Engine margin % 10

Design ship speed kn 16.3 and 15.5

Type of propeller FPP

No. of propeller blades 4

Propeller diameter m target

Based on the above-stated average

ship particulars assumed, we have

made a power prediction calculation

(Holtrop & Mennen’s Method) for dif-

ferent design ship speeds and propel-

ler diameters, and the corresponding

SMCR power and speed, point M, for

propulsion of the VLCC is found, see

Fig. 3. The propeller diameter change

corresponds approximately to the con-

stant ship speed factor α = 0.28 [PM2 =

PM1 x (n2/n1)α].

Referring to the two ship speeds of

16.3 knots and 15.5 knots, respective-

ly, four potential main engine types and

pertaining layout diagrams and SMCR

points have been drawn-in in Fig. 3, and

the main engine operating costs have

been calculated and described below

individually for each ship speed case.

The layout diagram of the G80ME-C9.2

below or equal to 68 r/min is especially

suitable for VLCCs whereas the speed

range from 68 to 72 r/min is particularly

suitable for e.g. container vessels.

It should be noted that the ship speed

stated refers to NCR = 90% SMCR in-

cluding 15% sea margin. If based on

calm weather, i.e. without sea margin,

the obtainable ship speed at NCR =

90% SMCR will be about 0.7 knots

higher.

If based on 75% SMCR, as applied for

calculation of the EEDI, the ship speed

will be about 0.1 knot lower, still based

on calm weather conditions, i.e. with-

out any sea margin.

8 Propulsion of VLCC

0

10,000

15,000

5,000

20,000

25,000

30,000

Relative powerreduction

%

Propulsion power demand at N = NCR

kW

0

1

2

3

4

5

6

7

8

9

10

11

12

7S80ME-C9.2N1

10.0 m

6S90ME-C8.2N2

10.0 m

7G80ME-C9.2N3

10.8 m

7G80ME-C9.2N4

11.0 mDprop:

28,410 kW

Inclusive of sea margin = 15%

28,410 kW27,340 kW 27,080 kW

0% 0%

3.8%

4.7%

Propulsion of 320,000 dwt VLCC – 16.3 knotsExpected propulsion power demand at N = NCR = 90% SMCR

Fig. 4: Expected propulsion power demand at NCR for 16.3 knots

Main Engine Operating Costs – 16.3 knots

The calculated main engine examples

are as follows:

16.3 knots

1. 7S80ME-C9.2

M1 = 31,570 kW x 78.0 r/min

2. 6S90ME-C8.2

M2 = 31,570 kW x 78.0 r/min.

3. 7G80ME-C9.2

M3 = 30,380 kW x 68.0 r/min.

4. 7G80ME-C9.2

M4 = 30,090 kW x 65.7 r/min.

The main engine fuel consumption and

operating costs at N = NCR = 90%

SMCR have been calculated for the

above four main engine/propeller cases

operating on the relatively high ship

speed of 16.3 knots, as often used

earlier. Furthermore, the corresponding

EEDI has been calculated on the basis

of the 75% SMCR-related figures (with-

out sea margin).

Fuel consumption and EEDI

Fig. 4 shows the influence of the pro-

peller diameter when going from about

10.0 to 11.0 m. Thus, N4 for the

7G80ME-C9.2 with an 11.0 m propel-

ler diameter has a propulsion power

demand that is about 4.7% lower

compared with N1 and N2 valid for

the 7S80ME-C9.2 and 6S90ME-C8.2,

both with a propeller diameter of about

10.0 m.

9Propulsion of VLCC

Fig. 5 shows the influence on the main

engine efficiency, indicated by the Spe-

cific Fuel Oil Consumption, SFOC, for

the four cases. N3 = 90% M3 for the

7G80ME-C9.2 has an SFOC of 164.1

g/kWh, whereas the N4 = 90% M4,

also for the 7G80ME-C9.2, has a high-

er SFOC of 164.8 g/kWh because of

the higher mean effective pressure.

The 164.8 g/kWh SFOC of the N4 for

the 7G80ME-C9.2 is 0.6% lower com-

pared with N1 for the nominally rated

7S80ME-C9.2 with an SFOC of 165.8

g/kWh. This is because of the higher

stroke/bore ratio of this G-engine type.

Engine shaft power25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 % SMCR

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

SFOCg/kWh

IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg

Standard high-loadoptimised engines

N3

N1

N4

N2

M = SMCRN = NCR

M3 7G80ME-C9.2

M4 7G80ME-C9.2

M2 6S90ME-C8.2M1 7S80ME-C9.2

10.8 m

11.0 m

10.0 m10.0 m

Dprop

Savingsin SFOC0%

0.6%

1.0%

Propulsion of 320,000 dwt VLCC – 16.3 knotsExpected SFOC

Fig. 5: Expected SFOC for 16.3 knots

10 Propulsion of VLCC

0

0.5

1.0

1.5

2.0

2.5

3.0

7S80ME-C9.21

10.0 m

6S90ME-C8.22

10.0 m

7G80ME-C9.23

10.8 m

7G80ME-C9.24

11.0 m

2.65

2.51 106%2.65

2.51 106% 2.542.51101%

2.502.51100%

Dprop:

0

20

30

40

50

60

70

80

90

100

110

10

Reference and actual EEDICO2 emissions gram per dwt/n mile Actual/Reference EEDI %

EEDI reference EEDI actual

Propulsion of 320,000 DWT VLCC – 16.3 knotsEnergy Efficiency Design Index (EEDI) 75% SMCR; 16.2 kn without sea margin

Fig. 7: Reference and actual Energy Efficiency Design Index (EEDI) for 16.3 knots

t/24h

0

10

20

30

40

50

60

70

80

90

100

110

120

0

1

2

3

4

5

6

7

8

9

10

11

12

Relative saving of fuel consumption

Fuel consumptionof main engine

%

IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg

113.1t/24h

7S80ME-C9.2N1

10.0 m

113.0t/24h

6S90ME-C8.2N2

10.0 m

107.7t/24h

7G80ME-C9.2N3

10.8 m

107.1t/24h

7G80ME-C9.2N4

11.0 m

0%0%

4.8%5.3%

Dprop:

Propulsion of 320,000 dwt VLCC – 16.3 knotsExpected fuel consumption at N = NCR = 90% SMCR

Fig. 6: Expected fuel consumption at NCR for 16.3 knots

When multiplying the propulsion power

demand at N (Fig. 4) with the SFOC

(Fig. 5), the daily fuel consumption is

found and is shown in Fig. 6. Com-

pared with N1 for the 7S80ME-C9.2,

the total reduction of fuel consumption

of the 7G80ME-C9.2 at N4 is about 5.3 %

(see also the above-mentioned 4.7%

and 0.6%).

The reference and the actual EEDI

figures have been calculated and are

shown in Fig. 7 (EEDIRef = 1,218.8 x

DWT -0.488, 15 July 2011). As can be

seen for all four cases, the actual EEDI

figures are higher than or equal to the

reference figure. However, this is to be

expected for VLCC operation on a ship

speed as high as 16.3 knots.

11Propulsion of VLCC

Operating costs

The total main engine operating costs

per year, 250 days/year, and fuel price

of 700 USD/t, are shown in Fig. 8. The

lube oil and maintenance costs are

shown too. As can be seen, the major

operating costs originate from the fuel

costs – about 96%.

The relative savings in operating costs

in Net Present Value (NPV), see Fig. 9,

with the 7S80ME-C9.2 or 6S90ME-

C8.2 used as basis with the propeller

diameter of about 10.0 m, indicates an

NPV saving for the 7G80ME-C9.2 en-

gines after some years in service. After

25 year in operation, the saving is about

16.7 million USD for N3 with 7G80ME-

C9.2 with the SMCR speed of 68.0 r/

min and propeller diameter of about

10.8 m, and about 18.4 million USD for

N4 also with 7G80ME-C9.2, but with

the SMCR speed of 65.7 r/min and a

propeller diameter of about 11.0 m.

Fig. 8: Total annual main engine operating costs for 16.3 knots

0

20

18

16

14

12

10

8

6

4

2

7S80ME-C9.2N1

10.0 m

MaintenanceLub. oil

Fuel oil

6S90ME-C8.2N2

10.0 m

7G80ME-C9.2N3

10.8 m

7G80ME-C9.2N4

11.0 m

0

10

22 11

9

8

7

6

5

4

3

2

1

IMO Tier llISO ambient conditions250 days/yearNCR = 90% SMCRFuel price: 700 USD/t

Annual operating costsMillion USD/Year

Relative saving in operating costs

%

0%

0.1%

4.7%5.2%

Dprop:

Propulsion of 320,000 dwt VLCC – 16.3 knotsTotal annual main engine operating costs

Million USD

LifetimeYears

0

10

20

25

5

15

0 5 10 15 20 25 30–5

IMO Tier llISO ambient conditionsN = NCR = 90% SMCR250 days/yearFuel price: 700 USD/tRate of interest and discount: 6% p.a.Rate of inflation: 3% p.a.

N3 10.8 m7G80ME-C9.2

N2 10.0 m6S90ME-C8.2N1 10.0 m7S80ME-C9.2

N4 11.0 m 7G80ME-C9.2

Propulsion of 320,000 dwt VLCC – 16.3 knotsRelative saving in main engine operating costs (NPV)Saving in operating costs(Net Present Value)

Fig. 9: Relative saving in main engine operating costs (NPV) for 16.3 knots

12 Propulsion of VLCC

24,350 kW

0

10,000

15,000

5,000

20,000

25,000

30,000

Relative powerreduction

%

Propulsion power demand at N’ = NCR

kW

0

1

2

3

4

5

6

7

8

9

10

11

12

Inclusive of sea margin = 15%

6S80ME-C9.2N1’

9.7 m

24,170 kW

6S90ME-C7.1N2’

9.8 m

23,440 kW

6G80ME-C9.2N3’

10.4 m

22,830 kW

7G80ME-C9.2N4’

11.0 m

0%

0.7%

3.8%

6.2%

Dprop:

Propulsion of 320,000 dwt VLCC – 15.5 knotsExpected propulsion power demand at N’ = NCR = 90% SMCR

Fig. 10: Expected propulsion power demand at NCR for 15.5 knots

Main Engine Operating Costs – 15.5 knots

The calculated main engine examples

are as follows:

15.5 knots

1’. 6S80ME-C9.2

M1’ = 27,060 kW x 78.0 r/min

2’. 6S90ME-C7.1

M2’ = 26,860 kW x 76.0 r/min.

3’. 6G80ME-C9.2

M3’ = 26,040 kW x 68.0 r/min.

4’. 7G80ME-C9.2

M4’ = 25,370 kW x 62.0 r/min.

The 6S90ME-C7.1 has been chosen as

case 2’ as often used in the past.

The main engine fuel consumption and

operating costs at N’ = NCR = 90%

SMCR have been calculated for the

above four main engine/propeller cases

operating on the relatively lower ship

speed of 15.5 knots, which is probably

going to be a more normal choice in

the future. Furthermore, the EEDI has

been calculated on the basis of the

75% SMCR-related figures (without

sea margin).

Fuel consumption and EEDI

Fig. 10 shows the influence of the

propeller diameter when going from

about 9.7 to 11.0 m. Thus, N4’ for the

7G80ME-C9.2 with an 11.0 m propel-

ler diameter has a propulsion power

demand that is about 6.2% lower com-

pared with the N1’ for the 6S80ME-

C9.2 with an about 9.7 m propeller

diameter. The choice of the one extra

cylinder for the 7G80ME-C9.2 has

made it possible to choose the large

11.0 m. propeller.

13Propulsion of VLCC

Engine shaft power

15925 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 % SMCR

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

SFOCg/kWh

175

176

10.4 m

9.8 m9.7 m

Dprop

IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg

Standard high-loadoptimised engines

N4’

N2’

N3’

N1’

M1’ = SMCRN1’ = NCR

M4’

7G80ME-C9.2

M3’ 6G80ME-C9.2

M2’ 6S90ME-C7.1M1’ 6S80ME-C9.2

11.0 m

Savingsin SFOC0%

0.3%

1.0%

2.5%

Propulsion of 320,000 dwt VLCC – 15.5 knotsExpected SFOC

Fig. 11: Expected SFOC for 15.5 knots

Fig. 11 shows the influence on the main

engine efficiency, indicated by the Spe-

cific Fuel Oil Consumption, SFOC, for

the four cases. N4’ = 90% M4’ with

the 7G80ME-C9.2 has a relatively low

SFOC of 161.6 g/kWh compared with

the 165.8 g/kWh for N1’ = 90% M1’ for

the 6S80ME-C9.2, i.e. an SFOC reduc-

tion of about 2.5%, mainly caused by

the derating potential used for the one

cylinder bigger 7G80ME-C9.2 engine.

14 Propulsion of VLCC

t/24h

96.9t/24h

0

10

20

30

40

50

60

70

80

90

100

110

0

1

2

3

4

5

6

7

8

9

10

11

Relative saving of fuel consumption

Fuel consumptionof main engine

%

IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg

6S80ME-C9.2N1’

9.7 m

95.9t/24h

6S90ME-C7.1N2’

9.8 m

92.3t/24h

6G80ME-C9.2N3’

10.4 m

88.6t/24h

7G80ME-C9.2N4’

11.0 m

0%

1.0%

4.8%

8.6%

Dprop:

Propulsion of 320,000 dwt VLCC – 15.5 knotsExpected fuel consumption at N’ = NCR = 90% SMCR

0 0

20

30

40

50

60

70

80

90

100

110

10

0.5

1.0

1.5

2.0

2.52.51 2.51 2.51 2.51

2.40 2.372.28

2.19

3.0

Reference and actual EEDICO2 emissionsgram per dwt/n mile Actual/Reference EEDI %

EEDI reference EEDI actual

Dprop:

6S80ME-C9.21’

9.7 m

6S90ME-C7.12’

9.8 m

6G80ME-C9.23’

10.4 m

7G80ME-C9.24’

11.0 m

95% 95%91%

87%

Propulsion of 320,000 DWT VLCC – 15.5 knotsEnergy Efficiency Design Index (EEDI)75% SMCR; 15.4 kn without sea margin

Fig. 13: Reference and actual Energy Efficiency Design Index (EEDI) for 15.5 knots

Fig. 12: Expected fuel consumption at NCR for 15.5 knots

The daily fuel consumption is found by

multiplying the propulsion power de-

mand at N’ (Fig. 10) with the SFOC (Fig.

11), see Fig. 12. The total reduction

of fuel consumption of the 7G80ME-

C9.2 is about 8.6% compared with the

6S80ME-C9.2.

The reference and the actual EEDI

figures have been calculated and are

shown in Fig. 13 (EEDIRef = 1,218.8 x

DWT -0.488, 15 July 2011). As can be

seen for all four cases, the actual EEDI

figures are now lower than the reference

figure because of the relatively low ship

speed of 15.5 knots. Particularly, case

4’ with 7G80ME-C9.2 has a low EEDI –

about 87% of the reference figure.

15Propulsion of VLCC

Annual operating costsMillion USD/Year

0

8

16

2

4

6

12

10

18

14

6S80ME-C9.2N1’

9.7 m

6S90ME-C7.1N2’

9.8 m

6G80ME-C9.2N3’

10.4 m

7G80ME-C9.2N4’

11.0 m

IMO Tier llISO ambient conditionsN’ = NCR = 90% SMCR250 days/yearFuel price: 700 USD/t

0

8

16

4

12

2

10

18

6

14

Relative saving in operating costs

%

4.7%

8.2%

0%

0.9%

MaintenanceLub. oil

Fuel oil

Dprop:

Propulsion of 320,000 dwt VLCC – 15.5 knotsTotal annual main engine operating costs

Fig. 14: Total annual main engine operating costs for 15.5 knots

Operating costs

The total main engine operating costs

per year, 250 days/year, and fuel price

of 700 USD/t, are shown in Fig. 14.

Lube oil and maintenance costs are

also shown at the top of each column.

As can be seen, the major operating

costs originate from the fuel costs –

about 96%.

The relative savings in operating costs

in Net Present Value, NPV, see Fig. 15,

with the 6S80ME-C9.2 with the propel-

ler diameter of about 9.7 m used as ba-

sis, indicates an NPV saving after some

years in service for the G80ME-C9.2

engines. After 25 years in operation, the

saving is about 14.3 million USD for the

6G80ME-C9.2 with the SMCR speed

of 68.0 r/min and propeller diameter

of about 10.4 m, and about 25.1 mil-

lion USD for the derated 7G80ME-C9.2

with the low SMCR speed of 62.0 r/min

and a propeller diameter of about 11.0 m.

16 Propulsion of VLCC

Million USD

LifetimeYears

0

10

20

35

30

5

15

25

0 5 10 15 20 25 30–5

Saving in operating costs(Net Present Value)

IMO Tier llISO ambient conditionsN’ = NCR = 90% SMCR250 days/yearFuel price: 700 USD/tRate of interest and discount: 6% p.a.Rate of inflation: 3% p.a.

N3’ 10.4 m6G80ME-C9.2

N2’ 9.8 m6S90ME-C7.1

N1’ 9.7 m6S80ME-C7.1

N4’ 11.0 m7G80ME-C9.2

Propulsion of 320,000 dwt VLCC – 15.5 knotsRelative saving in main engine operating costs (NPV)

Fig. 15: Relative saving in main engine operating costs (NPV) for 15.5 knots

Summary

Traditionally, super long stroke S-type

engines, with relatively low engine

speeds, have been applied as prime

movers in tankers.

Following the efficiency optimisation

trends in the market, the possibility of

using even larger propellers has been

thoroughly evaluated with a view to us-

ing engines with even lower speeds for

propulsion of particularly VLCCs.

VLCCs may be compatible with pro-

pellers with larger propeller diameters

than the current designs, and thus high

efficiencies following an adaptation of

the aft hull design to accommodate the

larger propeller, together with optimised

hull lines and bulbous bow, considering

operation in ballast conditions.

The new ultra long stroke G80ME-C9.2

engine type meets this trend in the

VLCC market. This paper indicates,

depending on the propeller diameter

used, an overall efficiency increase of

4-9% when using G80ME-C9.2, com-

pared with existing main engines ap-

plied so far.

The Energy Efficiency Design Index

(EEDI) will also be reduced when us-

ing G80ME-C9.2. In order to meet the

stricter given reference figure in the fu-

ture, the design of the ship itself and

the design ship speed applied (reduced

speed) has to be further evaluated by

the shipyards to further reduce the

EEDI. Among others, the installation of

WHR may reduce the EEDI value.

17Propulsion of VLCC

MAN Diesel & Turbo

Teglholmsgade 412450 Copenhagen SV, DenmarkPhone +45 33 85 11 00Fax +45 33 85 10 30info-cph@mandieselturbo.comwww.mandieselturbo.com

MAN Diesel & Turbo – a member of the MAN Group

All data provided in this document is non-binding. This data serves informational purposes only and is especially not guaranteed in any way. Depending on the subsequent specific individual projects, the relevant data may be subject to changes and will be assessed and determined individually for each project. This will depend on the particular characteristics of each individual project, especially specific site and operational conditions. Copyright © MAN Diesel & Turbo. 5510-0106-01ppr Aug 2012 Printed in Denmark