Propulsion of VLCC
Jan 05, 2016
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 [email protected]
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