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Propulsion of 46000 50000 Dwt Handymax Tanker
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Propulsion of 46,000-50,000 dwtHandymax Tanker
Content
Introduction .................................................................................................5
EEDI and Major Ship and Main Engine Parameters........................................6
Energy Efficiency Design Index (EEDI) ......................................................6
Major propeller and engine parameters ....................................................7
46,000-50,000 dwt Handymax tanker .....................................................9
Main Engine Operating Costs – 15.1 knots ................................................. 10
Fuel consumption and EEDI .................................................................. 10
Operating costs .................................................................................... 13
Main Engine Operating Costs – 14.5 knots ................................................. 14
Fuel consumption and EEDI .................................................................. 14
Operating costs .................................................................................... 17
Summary ................................................................................................... 18
Propulsion of 46,000-50,000 dwt Handymax Tanker
Introduction
The main ship particulars of 46,000-
50,000 dwt Handymax tankers are nor-
mally as follows: the overall ship length
is 183 m, breadth 32.2 m and design/
scantling draught 11.0 m/12.2 m, see
Fig. 1.
Recent development steps have made
it possible to offer solutions which will
enable significantly lower transportation
costs for Handymax tankers (and bulk
carriers) 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 operation
at lower than normal service ship speeds
compared to earlier, resulting in reduced
propulsion power utilisation. The design
ship speed at Normal Continuous Rating
(NCR), including 15% sea margin, used
to be as high as 15.0-15.5 knots. Today,
the ship speed may be expected to be
lower, possibly 14.5 knots, or even lower.
A more technically advanced develop-
ment drive is to optimise the aftbody
and hull lines of the ship – including bul-
bous bow, also considering operation
in ballast condition – making it possible
to install propellers with a larger pro-
peller diameter and, thereby, obtaining
higher propeller efficiency, but at a re-
duced optimum propeller speed.
As the two-stroke main engine is direct-
ly coupled with the propeller, the intro-
Fig. 1: Handymax tanker
5Propulsion of 46,000-50,000 dwt Handymax Tanker
duction of the ‘Green’ ultra long stroke
G50ME-B9.3 engine with even lower
than usual shaft speed will meet this
drive and target goal. The main dimen-
sions for this engine type, and for other
existing Handymax tanker (and bulk
carrier) engines, are shown in Fig. 2.
On the basis of a case study of a
47,000 dwt Handymax tanker in com-
pliance with IMO Tier II emission rules,
this paper shows the influence on fuel
consumption when choosing the new
G50ME-B engine compared with ex-
isting Handymax tanker engines. The
layout ranges of 6 and 7G50ME-B9.3
engines compared with 6 and 7S50ME-
B9.3 and existing 6 and 7S50ME-C8.2
engines are shown in Fig. 4.
EEDI and Major Ship and Main Engine ParametersEnergy Efficiency Design Index (EEDI)
The Energy Efficiency Design Index
(EEDI) is a mandatory instrument to be
calculated and made as available infor-
mation for new ships contracted after
1 January 2012. 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 essential-
ly calculated on the basis of maximum
cargo capacity, propulsion power, ship
speed, SFOC (Specific Fuel Oil Con-
sumption) and fuel type. However, cer-
tain correction factors are applicable,
e.g. for installed Waste Heat Recov-
G50ME-B9
9,91
5
3,896
1,86
01,
205
S50ME-B9
9,32
0
3,350
1,76
5
1,19
0
S50ME-C8
8,58
6
3,150
1,67
31,
098
Fig. 2: Main dimensions for a G50ME-B9 engine and for other existing Handymax tanker engines
ery systems. To evaluate the achieved
EEDI, a reference value for the specific
ship type and the specified cargo ca-
pacity is used for comparison.
The main engine’s 75% SMCR (Speci-
fied Maximum Continuous Rating)
figure is as standard applied in the cal-
culation of the EEDI figure, in which
also the CO2 emission from the auxil-
iary engines 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 present reference
figure (2012).
6 Propulsion of 46,000-50,000 dwt Handymax Tanker
8,500
9,000
9,500
10,000
70 8060 90 100 110 120 130 140 150 160 r/minEngine/propeller speed at SMCR
PropulsionSMCR power
kW
1.05
0.95
7.3 m
0.850.76
0.78
0.65
0.60
0.55
p/d
G50ME-B9.3
S50ME-C8.2
S50ME-B9.3
G50ME-B9.3
S50ME-C8.2
S50ME-B9.3
Power and speed curve for the given propeller diameter d = 6.8 m with different p/d ratios
Power and speed curve for various propeller diameters (d) with optimum p/d ratio
SMCR power and speed are inclusive of:15% sea margin10% engine margin 5% propeller light running
4-bladed FP-propellersd = Propeller diameterp/d = Pitch/diameter ratio Design Ship Speed = 15.0 knDesign Draught = 11.0 m
6.8 m
6.3 m
5.8 m
p/dd
0.72
0.74
Fig. 3: Influence of propeller diameter and pitch on SMCR for a 46,000-50,000 dwt Handymax tanker operating at 15.0 knots
Major propeller and engine parameters
In general, the highest possible pro-
pulsive efficiency required to provide a
given ship speed is obtained with the
largest possible propeller diameter d,
in combination with the corresponding,
optimum pitch/diameter ratio p/d.
As an example, this is illustrated for a
46,000-50,000 dwt Handymax tanker
with a service ship speed of 15 knots,
see the black curve on Fig. 3. The need-
ed propulsion SMCR (Specified Maxi-
mum Continuous Rating) power and
speed is shown for a given optimum
propeller diameter d and p/d ratio.
According to the black curve, the ex-
isting propeller diameter of 5.8 m may
have the optimum pitch/diameter ratio
of 0.72, and the lowest possible SMCR
shaft power of about 9,900 kW at about
131 r/min.
The black curve shows that if a bigger
propeller diameter of 6.8 m is possible,
the necessary SMCR shaft power will
be reduced to about 9,050 kW at about
95 r/min, i.e. the bigger the propeller,
the lower the optimum propeller speed.
If the pitch for this diameter is changed,
the propulsive efficiency will be re-
duced, i.e. the necessary SMCR shaft
power will increase, see the red curve.
The red curve also shows that propul-
sion-wise it will always be an advantage
to choose the largest possible propel-
ler diameter, even though the optimum
pitch/diameter ratio would involve a
too low propeller speed (in relation to
the required main engine speed). Thus,
when using a somewhat lower pitch/
diameter ratio, compared with the op-
timum ratio, the propeller/engine speed
may be increased and will only cause a
minor extra power increase.
7Propulsion of 46,000-50,000 dwt Handymax Tanker
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 higher
the engine efficiency. This means, for
example, that an ultra long stroke en-
gine type, as the G50ME-B9.3, may
have a higher efficiency compared with
a shorter stroke engine type, like an
S50ME-C8.2.
The application of new propeller design
technologies may also motivate use of
main engines with lower rpm. Thus, for
the same propeller diameter, these pro-
peller types can demonstrate an up to
6% improved overall efficiency gain at
about 10% lower propeller speed.
This is valid for propellers with Kappel
technology available at MAN Diesel &
Turbo, Frederikshavn, Denmark.
Hence, with such a propeller type,
the advantage of the new low speed
G50ME-B9.3 engine can be utilised
also in case a correspondingly larger
propeller cannot be accommodated.
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
60 70 80 90 100 110 120 130 140 150 r/minEngine/propeller speed at SMCR
PropulsionSMCR powerkW
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 = 11.0 m
G50ME-B9.3Bore = 500 mmStroke = 2,500 mmVpist = 8.33 m/s (9.00 m/s)S/B = 5.00MEP = 21 barL1 = 1,720 kW/cyl. at 100 r/min(L1 = 1,860 kW/cyl. at 108 r/min)
M = SMCR (15.1 kn)M1 = 9,960 kW x 127 r/min, 6S50ME-C8.2 (L1)M2 = 9,730 kW x 117 r/min, 6S50ME-B9.3M3 = 9,310 kW x 100 r/min, 6G50ME-B9.3
M’ = SMCR (14.5 kn)M1’ = 8,500 kW x 119 r/min, 6S50ME-C8.2M2’ = 8,310 kW x 110 r/min, 6S50ME-B9.3M3’ = 7,950 kW x 94 r/min, 6G50ME-B9.3
PossibleDprop=6.3 m(= 57.3% of Tdes)
PossibleDprop=6.8 m(= 61.8% of Tdes)
ExistingDprop=5.8 m(= 52.7% of Tdes)
7G50ME-B9.3
16.0 kn
15.5 kn
15.0 kn15.1 kn
14.5 kn
14.0 kn
13.5 kn
∝
∝
∝
∝
∝
∝
∝
100 r/min 108 r/min 117 r/min 127 r/min
7S50ME-B9.3
6S50ME-B9.37S50ME-C8.2
6S50ME-C8.2
6G50ME-B9.3 M1M1’
M3
M3’
M2
M2’
Increased propeller diameterG50ME-B9.3
Fig. 4: Different main engine and propeller layouts and SMCR possibilities (M1, M2, M3 for 15.1 knots and M1’, M2’, M3’ for 14.5 knots) for a 46,000-50,000
dwt Handymax tanker operating at 15.1 knots and 14.5 knots, respectively
8 Propulsion of 46,000-50,000 dwt Handymax Tanker
46,000-50,000 dwt Handymax tanker
For a 47,000 dwt Handymax tanker, the
following case study illustrates the po-
tential for reducing fuel consumption by
increasing the propeller diameter and
introducing the G50ME-B9.3 as main
engine. The ship particulars assumed
are as follows:
Scantling draught m 12.2
Design draught m 11.0
Length overall m 183.0
Length between pp m 174.0
Breadth m 32.2
Sea margin % 15
Engine margin % 10
Design ship speed kn 15.1 and 14.5
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 Handymax tanker is
found, see Fig. 4. The propeller diame-
ter change corresponds approximately
to the constant ship speed factor α =
0.28 [ref. PM2 = PM1 x (n2/n1)α.
Referring to the two ship speeds of
15.1 knots and 14.5 knots, respective-
ly, three potential main engine types,
6S50MC-C8.2, 6S50ME-B9.3 and
6G50ME-B9.3 and pertaining layout
diagrams and SMCR points have been
drawn-in in Fig. 4, and the main engine
operating costs have been calculated
and described below individually for
each ship speed case.
The layout diagram of the G50ME-B9.3
below or equal to 100 r/min is especially
suitable for Handymax tankers (and bulk
carriers) whereas the speed range from
100 to 108 r/min is particularly suitable
for tankers with limited room for installa-
tion of a large propeller.
The S50MC-C and S50ME-C engines
(127 r/min) have often been used in the
past as prime movers for Handymax
tankers, and the relatively new S50ME-
B9 (117 r/min) has already been installed
in some ships. Therefore, a comparison
between the new 6G50ME-B9.3 and
the existing 6S50ME-C8.2 is of major
interest in this paper.
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 0.5 knots higher.
If based on 75% SMCR, as applied for
calculation of the EEDI, the ship speed
will be about 0.2 knot lower, still based
on calm weather conditions, i.e. with-
out any sea margin.
9Propulsion of 46,000-50,000 dwt Handymax Tanker
Main Engine Operating Costs – 15.1 knots
The calculated main engine examples
are as follows:
15.1 knots
1. 6S50ME-C8.2 (Dprop = 5.9 m)
M1 = 9,960 kW x 127.0 r/min
2. 6S50ME-B9.3 (Dprop = 6.2 m)
M2 = 9,730 kW x 117.0 r/min.
3. 6G50ME-B9.3 (Dprop = 6.7 m)
M3 = 9,310 kW x 100.0 r/min.
The main engine fuel consumption
and operating costs at N = NCR =
90% SMCR have been calculated for
the above three main engine/propeller
cases operating on the relatively high
ship speed of 15.1 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. 5 shows the influence of the pro-
peller diameter with four propeller
blades when going from about 5.9 m to
6.7 m. Thus, N3 for the 6G50ME-B9.3
with a 6.7 m propeller diameter has a
propulsion power demand that is about
6.5% lower compared with N1 valid for
the 6S50ME-C8.2 with a propeller di-
ameter of about 5.9 m.
0
4,000
6,000
2,000
8,000
10,000
Relative powerreduction
%
Propulsion power demand at N = NCR
kW
0
1
2
3
4
5
6
7
8
9
10
6S50ME-C8.2N1
5.9 m×4
6S50ME-B9.3N2
6.2 m×4
6G50ME-B9.3N3
6.7 m×4Dprop:
8,964 kW
Inclusive of sea margin = 15%
8,757 kW8,379 kW
0%
2.3%
6.5%
Propulsion of 47,000 dwt Handymax Tanker – 15.1 knotsExpected propulsion power demand at N = NCR = 90% SMCR
Fig. 5: Expected propulsion power demand at NCR = 90% SMCR for 15.1 knots
10 Propulsion of 46,000-50,000 dwt Handymax Tanker
Fig. 6 shows the influence on the main
engine efficiency, indicated by the Spe-
cific Fuel Oil Consumption, SFOC, for
the three cases. N3 = 90% M3 for the
6G50ME-B9.3 has an SFOC of 164.1
g/kWh and almost the same 164.3 g/
kWh for N2 = 90% M2 with 6S50ME-
B9.3 where in both cases for the ME-B
engine is included +1 g/kWh needed
for the Hydraulic Power Supply (HPS)
system.
The 164.1 g/kWh SFOC of the N3 for
the 6G50ME-B9.3 is 2.2% lower com-
pared with N1 for the nominally rated
6S50ME-C8.2 with an SFOC of 167.8
g/kWh. This is because of the great-
er derating potential and the higher
stroke/bore ratio of this G-engine type.
Engine shaft power
16225 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 % SMCR
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
SFOCg/kWh
178
179
180
N3
N1
N2
M3 6G50ME-B9.3M2 6S50ME-B9.3
M1 6S50ME-C8.2
6.7 m ×46.2 m ×4
5.9 m ×4Dprop
Savingsin SFOC
0%
2.1%2.2%
IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg
Standard high-loadoptimised engines
For ME-B9.3 engines the fuel consumption (+1g/kWh) for HPS is included.
M = SMCRN = NCR
Propulsion of 47,000 dwt Handymax Tanker – 15.1 knotsExpected SFOC
StandardME-B9.3(with VET)
ME-B9.2(without VET)
(VET = Variable Exhaust valve Timing)
Fig. 6: Expected SFOC for 15.1 knots
11Propulsion of 46,000-50,000 dwt Handymax Tanker
When multiplying the propulsion power
demand at N (Fig. 5) with the SFOC (Fig.
6), the daily fuel consumption is found
and is shown in Fig. 7. Compared with
N1 for the existing 6S50ME-C8.2, the
total reduction of fuel consumption of
the new 6G50ME-B9.3 at N3 is about
8.6% (see also the above-mentioned
savings of 6.5% and 2.2%).
The reference and the actual EEDI fig-
ures have been calculated and are
shown in Fig. 8 (EEDIref =1,218.8 x
dwt -0.488, 15 July 2011). As can be
seen for all three cases, the actual EEDI
figures are equal to or lower than the
reference figure. Particularly, case 3
with 6G50ME-B9.3 has a low EEDI –
about 92% of the reference figure.
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
90
100
110
120
Reference and actual EEDICO2 emissionsgram per dwt/n mile Actual/Reference EEDI %
EEDI reference 2012 EEDI actual
Dprop:
6S50ME-C8.2N1
5.9 m ×4
6S50ME-B9.3N2
6.2 m ×4
6G50ME-B9.3N3
6.7 m ×4
6.40 6.42
100%6.40
97%
6.40
5.9192%
6.18
Propulsion of 47,000 dwt Handymax Tanker – 15.1 knotsEnergy Efficiency Design Index (EEDI)75% SMCR: 14.9 kn without sea margin
Fig. 8: Reference and actual Energy Efficiency Design Index (EEDI) for 15.1 knots
15 2
310 4
515 6
720 8
925
30
35
40
10111213141516
Relative saving of fuel consumption
%
Fuel consumptionof main engine
t/24h
IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg
0 0
36.10t/24h 34.54
t/24h 33.00t/24h
0%
4.3%
8.6%
6S50ME-C8.2N1
5.9 m ×4
6S50ME-B9.3N2
6.2 m ×4
6G50ME-B9.3N3
6.7 m ×4Dprop:
For ME-B9.3 engines the fuel consumption for HPS is included.
Propulsion of 47,000 dwt Handymax Tanker – 15.1 knotsExpected fuel consumption at N = NCR = 90% SMCR
Fig. 7: Expected fuel consumption at NCR = 90% SMCR for 15.1 knots
12 Propulsion of 46,000-50,000 dwt Handymax Tanker
Fig. 9: Total annual main engine operating costs for 15.1 knots
0
2
4
6
1
3
5
6S50ME-C8.2N1
5.9 m×4
MaintenanceLub. oil
Fuel oil
6S50ME-B9.3N2
6.2 m×4
6G50ME-B9.3N3
6.7 m×4
0
4
8
12
2
6
10
1
5
9
3
7
11
7 14
13
Annual operating costsMillion USD/Year
Relative saving in operating costs
%
Dprop:
0%
4.2%
8.3%
Propulsion of 47,000 DWT Tanker – 15.1 knotsTotal annual main engine operating costs
IMO Tier llISO ambient conditions250 days/yearNCR = 90% SMCRFuel price: 700 USD/t
Million USD
LifetimeYears
0
4
8
12
2
6
10
0 5 10 15 20 25 30–2
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 6.7 m ×46G50ME-B9.3
N2 6.2 m ×46S50ME-B9.3
N1 5.9 m ×46S50ME-C8.2
Propulsion of 47,000 dwt Handymax Tanker – 15.1 knotsRelative saving in main engine operating costs (NPV)
Fig. 10: Relative saving in main engine operating costs (NPV) for 15.1 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. 9. The
lube oil and maintenance costs are
shown too. As can be seen, the major
operating costs originate from the fuel
costs – about 96%.
After some years in service, the rela-
tive savings in operating costs in Net
Present Value (NPV), see Fig. 10, with
the existing 6S50ME-C8.2 used as
basis with the propeller diameter of
about 5.9 m, indicates an NPV saving
for the new 6G50ME-B9.3 engine with
the propeller diameter of about 6.7 m.
After 25 years in operation, the saving
is about 9.6 million USD for N3 with
6G50ME-B9.3 with the SMCR speed
of 100.0 r/min and propeller diameter
of about 6.7 m.
13Propulsion of 46,000-50,000 dwt Handymax Tanker
Main Engine Operating Costs – 14.5 knots
The calculated main engine examples
are as follows:
14.5 knots
1’. 6S50ME-C8.2 (Dprop = 5.9 m)
M1’ = 8,500 kW x 119.0 r/min
2’. 6S50ME-B9.3 (Dprop = 6.2 m)
M2’ = 8,310 kW x 110.0 r/min.
3’. 6G50ME-B9.3 (Dprop = 6.7 m)
M3’ = 7,950 kW x 94.0 r/min.
The main engine fuel consumption and
operating costs at N’ = NCR = 90%
SMCR have been calculated for the
above three main engine/propeller cas-
es operating on the relatively lower ship
speed of 14.5 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 mar-
gin).
Fuel consumption and EEDI
Fig. 11 shows the influence of the
propeller diameter with four propeller
blades when going from about 5.9 m to
6.7 m. Thus, N3’ for the 6G50ME-B9.3
with an about 6.7 m propeller diameter
has a propulsion power demand that
is about 6.5% lower compared with
the N1’ for the 6S50ME-C8.2 with an
about 5.9 m propeller diameter. For
the two ME-B engine cases, an extra
SFOC of +1 g/kWh has been added
corresponding to the power demand
needed for the Hydraulic Power Supply
(HPS) system.
0
4,000
6,000
2,000
8,000
10,000
Relative powerreduction
%
Propulsion power demand at N = NCR
kW
0
1
2
3
4
5
6
7
8
9
10
6S50ME-C8.2N1’
5.9 m×4
6S50ME-B9.3N2’
6.2 m×4
6G50ME-B9.3N3’
6.7 m×4Dprop:
7,650 kW
Inclusive of sea margin = 15%
7,479 kW7,155 kW
0%
2.2%
6.5%
Propulsion of 47,000 dwt Handymax Tanker – 14.5 knotsExpected propulsion power demand at N = NCR = 90% SMCR
Fig. 11: Expected propulsion power demand at NCR = 90% SMCR for 14.5 knots
14 Propulsion of 46,000-50,000 dwt Handymax Tanker
Engine shaft power
16025 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 % SMCR
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
SFOCg/kWh179
N3’
N1’
N2’
M3’ 6G50ME-B9.3M2’ 6S50ME-B9.3
M1’ 6S50ME-C8.2
6.7 m ×46.2 m ×4
5.9 m ×4Dprop
Savingsin SFOC
0%
2.0%2.1%
IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg
Standard high-loadoptimised engines
For ME-B9.3 engines the fuel consumption (+1g/kWh) for HPS is included.
M’ = SMCRN’ = NCR
ME-B9.2(without VET)
StandardME-B9.3(with VET)
(VET = Variable Exhaust valve Timing)
Propulsion of 47,000 dwt Handymax Tanker – 14.5 knotsExpected SFOC
Fig. 12: Expected SFOC for 14.5 knots
Fig. 12 shows the influence on the main
engine efficiency, indicated by the Spe-
cific Fuel Oil Consumption, SFOC, for
the three cases. N3’ = 90% M3’ with
the 6G50ME-B9.3 has a relatively low
SFOC of 161.6 g/kWh compared with
the 165.1 g/kWh for N1’ = 90% M1’ for
the 6S50ME-C8.2, i.e. an SFOC reduc-
tion of about 2.1%, mainly caused by
the greater derating potential and higher
stroke/bore ratio of the G-engine type.
15Propulsion of 46,000-50,000 dwt Handymax Tanker
The daily fuel consumption is found by
multiplying the propulsion power de-
mand at N’ (Fig. 11) with the SFOC (Fig.
12), see Fig. 13. The total reduction of
fuel consumption of the new 6G50ME-
B9.3 is about 8.5% compared with the
existing 6S50ME-C8.2 (see also the
above-mentioned savings of 6.5% and
2.1%).
The reference and the actual EEDI
figures have been calculated and are
shown in Fig. 14 (EEDIref = 1,218.8
x dwt -0.488, 15 July 2011). As can be
seen for all three cases, the actual EEDI
figures are now somewhat lower than
the reference figure because of the
relatively low ship speed of 14.5 knots.
Particularly, case 3’ with 6G50ME-B9.3
has a low EEDI – about 82% of the ref-
erence figure.
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
90
100
110
120
Reference and actual EEDICO2 emissionsgram per dwt/n mile Actual/Reference EEDI %
EEDI reference 2012 EEDI actual
Dprop:
6S50ME-C8.2N1’
5.9 m ×4
6S50ME-B9.3N2’
6.2 m ×4
6G50ME-B9.3N3’
6.7 m ×4
6.40
5.7189%
6.40
86%
6.40
5.2682%
5.50
Propulsion of 47,000 dwt Handymax Tanker – 14.5 knotsEnergy Efficiency Design Index (EEDI)75% SMCR: 14.9 kn without sea margin
Fig. 14: Reference and actual Energy Efficiency Design Index (EEDI) for 14.5 knots
1
5 2
3
10 4
5
15 6
7
20 8
9
25
30
35
10
11
1213
14
Relative saving of fuel consumption
%
Fuel consumptionof main engine
t/24h
IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg
0 0
30.32t/24h 29.05
t/24h 27.75t/24h
0%
4.2%
8.5%
6S50ME-C8.2N1’
5.9 m ×4
6S50ME-B9.3N2’
6.2 m ×4
6G50ME-B9.3N3’
6.7 m ×4Dprop:
For ME-B9.3 engines the fuel consumption for HPS is included.
Propulsion of 47,000 dwt Handymax Tanker – 14.5 knotsExpected fuel consumption at N = NCR = 90% SMCR
Fig. 13: Expected fuel consumption at NCR = 90 SMCR for 14.5 knots
16 Propulsion of 46,000-50,000 dwt Handymax Tanker
0
2
4
1
3
5
6S50ME-C8.2N1’
5.9 m×4
MaintenanceLub. oil
Fuel oil
6S50ME-B9.3N2’
6.2 m×4
6G50ME-B9.3N3’
6.7 m×4
0
4
8
2
6
1
5
9
6
10
12
11
3
7
Annual operating costsMillion USD/Year
Relative saving in operating costs
%
Dprop:
IMO Tier llISO ambient conditions250 days/yearNCR = 90% SMCRFuel price: 700 USD/t
0%
4.0%
8.2%
Propulsion of 47,000 DWT Tanker – 14.5 knotsTotal annual main engine operating costs
Fig. 15: Total annual main engine operating costs for 14.5 knots
LifetimeYears
0
4
8
2
6
10
0 5 10 15 20 25 30–2
Saving in operating costs(Net Present Value)Million USD
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’ 6.7 m ×46G50ME-B9.3
N2’ 6.2 m ×46S50ME-B9.3
N1’ 5.9 m ×46S50ME-C8.2
Propulsion of 47,000 dwt Handymax Tanker – 14.5 knotsRelative saving in main engine operating costs (NPV)
Fig. 16: Relative saving in main engine operating costs (NPV) for 14.5 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. 15.
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%.
After some years in service, the rela-
tive savings in operating costs in Net
Present Value, NPV, see Fig. 16, with
the existing 6S50ME-C8.2 with the
propeller diameter of about 5.9 m
used as basis, indicates an NPV sav-
ing after some years in service for the
new 6G50ME-B9.3 engine with the
propeller diameter of about 6.7 m. Af-
ter 25 years in operation, the saving is
about 7.9 million USD for N3’ with the
6G50ME-B9.3 with the SMCR speed
of 94.0 r/min and propeller diameter of
about 6.7 m.
17Propulsion of 46,000-50,000 dwt Handymax Tanker
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 tankers (but
also bulk carriers).
Handymax tankers (and bulk carriers)
may be compatible with propellers with
larger propeller diameters than the cur-
rent designs, and thus high efficiencies
following an adaptation of the aft hull
design to accommodate the larger pro-
peller, together with optimised hull lines
and bulbous bow, considering opera-
tion in ballast conditions.
The new ultra long stroke G50ME-
B9.3 engine type meets this trend in
the Handymax tanker (and bulk carrier)
market. This paper indicates, depend-
ing on the propeller diameter used,
an overall efficiency increase of 8-9%
when using G50ME-B9.3, compared
with existing main engine type S50ME-
C8.2 applied so far.
Compared with existing S50MC-C8 or
even S50ME-C7/MC-C7 often used in
the past, the overall efficiency increase
will be even higher when using G50ME-
B9.3.
The Energy Efficiency Design Index
(EEDI) will also be reduced when us-
ing G50ME-B9.3. 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.
18 Propulsion of 46,000-50,000 dwt Handymax Tanker
MAN Diesel & TurboTeglholmsgade 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. 5510-0110-02ppr Dec 2012 Printed in Denmark