Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Transcript of Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Propulsion of 200,000-210,000 dwtLarge Capesize Bulk Carrier
Content
Introduction .................................................................................................5
EEDI and Major Ship and Main Engine Parameters........................................6
Energy Efficiency Design Index (EEDI) ......................................................6
Major propeller and engine parameters ....................................................7
205,000 dwt large capesize bulk carrier ..................................................9
Main Engine Operating Costs – 14.7 knots ................................................. 10
Fuel consumption and EEDI .................................................................. 10
Operating costs .................................................................................... 12
Main Engine Operating Costs – 14.0 knots ................................................. 14
Fuel consumption and EEDI .................................................................. 14
Operating costs .................................................................................... 17
Summary ................................................................................................... 18
Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Introduction
The main ship particulars of 205,000-
210,000 dwt large capesize bulk car-
riers are normally approximately as fol-
lows: the overall ship length is 299.9
m, breadth 50 m and scantling draught
17.9-18.4 m, see Fig. 1.
Recent development steps have made
it possible to offer solutions which will
enable significantly lower transporta-
tion costs for large capesize bulk carri-
ers 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 bulk carriers, the CO2 emission
from new bulk carriers in gram per dwt
per nautical mile must be equal to or
lower than the reference emission fig-
ures valid for the specific bulk carrier.
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 14.0-15.0 knots and
with an average of about 14.7 knots. To-
day, the required ship speed should be
expected to be lower, however it seems
to be unchanged.
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. This makes 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, i.e. us-
ing less power for the same ship speed.
Fig. 1: Large capesize bulk carrier
5Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
As the two-stroke main engine is directly
coupled with the propeller, the introduc-
tion of the ultra long stroke G70ME-C9.5
engine with even lower than usual shaft
speed will meet this goal. The main di-
mensions for this engine type, and for
the existing large capesize bulk carrier
engine S70ME-C8.5 are shown in Fig. 2.
On the basis of a case study of a
205,000 dwt large capesize bulk carrier
in compliance with IMO Tier II emission
rules, this paper shows the influence on
fuel consumption when choosing the
new G70ME-C9.5 engine compared
with the existing and normally used
S70ME-C8.5 engine. The layout ranges
of 5 and 6G70ME-C9.5 engines com-
pared with 6S70ME-C8.5 are shown
later in Fig. 4.
EEDI and Major Ship and Main Engine Parameters
Energy Efficiency Design Index (EEDI)
The IMO (International Maritime Organi-
sation) based Energy Efficiency Design
Index (EEDI) is a mandatory index re-
quired on all new ships contracted after
1 January 2013. The index is used as
an instrument to fulfil international re-
quirements regarding CO2 emissions
on ships. EEDI represents the amount
of CO2 emitted by a ship in relation to
the transported cargo and is measured
in gram CO2 per dwt per nautical mile.
The EEDI value is calculated on the
basis of maximum cargo capacity (yet
70% for container ships), propulsion
power, ship speed, SFOC (Specific Fuel
Oil Consumption) and fuel type. De-
S70ME-C8.5G70ME-C9.5
1,52
1
2,32
6
12,0
66
1,75
0
2,72
0
4,760 4,390
13,2
45
Fig. 2: Main dimensions for the new G70ME-C9.5 engine and the existing S70ME-C8.5 applied earlier
pending on the date of ship contract,
the EEDI is required to be a certain
percentage lower than an IMO defined
reference value depending on the type
and capacity of the ship.
The main engine’s 75% SMCR (Speci-
fied Maximum Continuous Rating) fig-
ure is as standard applied in the cal-
culation of the EEDI figure, in which
also the CO2 emission from the auxiliary
engines of the ship is included. How-
ever, certain correction figures are ap-
plicable, e.g. for installed waste heat
recovery systems.
According to the rules finally decided
on 15 July 2011, the EEDI of a new
ship is reduced to a certain factor com-
pared to a reference value. Thus, a ship
6 Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Fig. 3: Influence of propeller diameter and pitch on SMCR for a 205,000 dwt large capesize bulk carrier operating at 14.7 knots
bigger than 20,000 dwt and built after
2025 is required to have a 30% lower
EEDI than the 2013 reference figure,
see also later in Figs. 8 and 14.
Major propeller and engine param-
eters
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
205,000 dwt large capesize bulk carrier
with a service ship speed of 14.7 knots,
see the black curve in 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 8.3 m may
have the optimum pitch/diameter ratio
of 0.71, and the lowest possible SMCR
shaft power of about 17,680 kW at
about 88 r/min.
The black curve shows that if a bigger
propeller diameter of 8.8 m is possible,
the necessary SMCR shaft power will be
reduced to about 17,120 kW at about
78 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.
14,000
17,000
18,000
15,000
16,000
19,000
60 65 70 75 80 85 90 95 100 105 r/minEngine/propeller speed at SMCR
PropulsionSMCR power
kW
S70ME-C8.5
Power and speed curve for the given propeller diameter d = 8.8 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 = 14.7 knDesign Draught = 16.1 m
G70ME-C9.5
G70ME-C9.5S70ME-C8.5
0.95
0.850.73
0.75
9.3 m
8.3 m
8.8 m0.71
p/dd
0.650.60
p/d
7Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
0
5,000
10,000
15,000
20,000
25,000
30,000
40 50 60 70 80 90 100 110 120 r/minEngine and propeller speed at SMCR
PropulsionSMCR powerkW
Possible9.3 m × 4
57.8%
Existing8.8 m × 4
54.7%
Existing8.3 m × 4
51.6%
∝
∝∝
∝
∝
Dprop × Nblade:Dprop /Tdes=
14.0 kn14.0 kn, 8.3 m × 4M1’ = 15,190 kW × 84 r/min (6S70ME-C8.5) 14.0 kn, 8.8 m × 4M2’ = 14,720 kW × 75 r/min (5G70ME-C9.5) 14.0 kn, 9.3 m × 4M3’ = 14,260 kW × 67 r/min (5G70ME-C9.5) 14.0 kn, 9.3 m × 4M4’ = 14,260 kW × 67 r/min (6G70ME-C9.5)
14.7 kn14.7 kn, 8.2 m × 4M1 = 17,840 kW × 91 r/min (6S70ME-C8.5) 14.7 kn, 8.7 m × 4M2 = 17,270 kW × 81 r/min (6S70ME-C8.5) 14.7 kn, 8.7 m × 4M3 = 17,270 kW × 81 r/min (6G70ME-C9.5) 14.7 kn, 9.3 m × 4M4 = 16,640 kW × 71 r/min (6G70ME-C9.5)
4 bladed FP-propellersConstant ship speed coefficient ∝ = 0.28
SMCR power and speed are inclusive of:15% sea margin10% engine margin5% light running
Tdes = 16.1 m
16.0 kn
15.0 kn14.7 kn
14.0 kn
13.0 kn
91 r/min83 r/min
6G70ME-C9.5
5G70ME-C9.5
6S70ME-C8.5
M4M4’
M3’M2’ M1’
M2M3
M1
Fig. 4: Different main engine and propeller layouts and SMCR possibilities (M1, M2, M3, M4 for 14.7 knots and M1’, M2’, M3’, M4’ for 14.0 knots) for a
205,000 dwt large capesize bulk carrier operating at 14.7 knots and 14.0 knots, respectively
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 G70ME-C9.5, may
have a higher efficiency compared with
a shorter stroke engine type, like a su-
per long stroke S70ME-C8.5.
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
4% improved overall efficiency gain at the
same or a slightly lower propeller speed.
This is valid for propellers with Kappel
technology available at MAN Diesel &
Turbo, Frederikshavn, Denmark.
Furthermore, due to lower emitted
pressure impulses, the kappel propel-
ler requires less tip clearance that can
be utilised for installing an even larger
propeller diameter, resulting in a further
increase of the propeller efficiency.
Hence, with such a propeller type,
the advantage of the new low speed
G70ME-C9.5 engine can be utilised
also in case a correspondingly larger
propeller cannot be accommodated.
8 Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
205,000 dwt large capesize bulk
carrier
For a 205,000 dwt large capesize bulk
carrier, the following case study illus-
trates the potential for reducing fuel
consumption by increasing the pro-
peller diameter and introducing the
G70ME-C9.5 as main engine. The ship
particulars assumed are as follows:
Scantling draught m 18.2
Design draught m 16.1
Length overall m 299.9
Length between pp m 291.0
Breadth m 50.0
Sea margin % 15
Engine margin % 10
Design ship speed kn 14.7 and 14.0
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 large capesize bulk
carrier is found, see Fig. 4. The propel-
ler diameter change corresponds ap-
proximately to the constant ship speed
factor α = 0.28 [ref. PM2 = PM1 × (n2/
n1)α.
Referring to the two ship speeds of 14.7
knots and 14.0 knots, respectively, two
potential main engine types, pertaining
layout diagrams and SMCR points have
been drawn-in in Fig. 4, and the main
engine operating costs have been cal-
culated and described.
The S70ME-C8.5 engine type (91 r/
min) has often been used in the past
as prime movers in projects for large
capesize bulk carriers. Therefore, a
comparison between the new G70ME-
C9.5 and the existing S70ME-C8.5 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 0.6 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 200,000-210,000 dwt Large Capesize Bulk Carrier
1
6,000
8,000
2
3
4
5
6
7
8
9
Relative powerreduction
%Inclusive of sea margin = 15%
Propulsion power demand at N = NCR
kW
0
2,000
4,000
0
16,000
18,000
10,000
12,000
14,000
Dprop:
16,056 kW
6S70ME-C8.5N1
8.2 m × 4
0%
15,543 kW
6S70ME-C8.5N2
8.7 m × 4
3.2%
15,543 kW
6G70ME-C9.5N3
8.7 m × 4
3.2%
14,976 kW
6G70ME-C9.5N4
9.3 m × 4
6.7%
Fig. 5: Expected propulsion power demand at NCR = 90% SMCR for 14.7 knots
Main Engine Operating Costs – 14.7 knots
The calculated main engine examples
are as follows:
14.7 knots
1. 6S70ME-C8.5 (Dprop = 8.2 m)
M1 = 17,840 kW × 91.0 r/min
2. 6S70ME-C8.5 (Dprop = 8.7 m)
M2 = 17,270 kW × 81.0 r/min.
3. 6G70ME-C9.5 (Dprop = 8.7 m)
M3 = 17,270 kW × 81.0 r/min.
4. 6G70ME-C9.5 (Dprop = 9.3 m)
M4 = 16,640 kW × 71.0 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 average ship speed of
14.7 knots, as often used earlier, but
also today, despite the EEDI demands.
Furthermore, the corresponding EEDI
has been calculated on the basis of the
75% SMCR-related figures (without sea
margin).
Fuel consumption and EEDI
Fig. 5 shows the influence of the pro-
peller diameter with four propeller
blades when going from about 8.2 m to
9.3 m. Thus, N4 for the 6G70ME-C9.5
with a 9.3 m propeller diameter has a
propulsion power demand that is about
6.7% lower compared with N1 valid for
the 6S70ME-C8.5 with a propeller di-
ameter of about 8.2 m.
10 Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Fig. 6 shows the influence on the main
engine efficiency, indicated by the
Specific Fuel Oil Consumption, SFOC,
for the four cases. For N3 = 90% M3
with the 6G70ME-C8.5 SFOC is 159.1
g/kWh and for N1 = 90% M1 with
6S70ME-C8.5 SFOC is 164.1 g/kWh.
In N3, the SFOC is about 3.0% lower
compared with N1.
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 6S70ME-C8.5,
the total reduction of fuel consump-
tion of the new 6G70ME-C9.5 at N3
is about 6.1% and at N4 about 8.2%
(see also the above-mentioned savings
of 3.2%/6.7% (Fig. 5) and 3.0%/1.6%
(Fig. 6).
Engine shaft power
174
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100% SMCR156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
SFOCg/kWh
171
172
173 IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg
Standard high-loadoptimised engines
M = SMCRN = NCR
N1
N3
N2
N
N4
Savings in SFOC
0.0%Basis-1.5%
1.6%
3.0%
DpropM2 6S70ME-C8.5 8.7 m x 4
M1 6S70ME-C8.5 8.2 m x 4
M4 6G70ME-C9.5 9.3 m x 4
M3 6G70ME-C9.5 8.7 m x 4
Fig. 6: Expected SFOC for 14.7 knots
11Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
2.592.48
2.42
2.63
6S70ME-C8.5N1
8.2 m × 4
6S70ME-C8.5N2
8.7 m × 4
6G70ME-C9.5N3
8.7 m × 4
6G70ME-C9.5N4
9.3 m × 4Dprop:
0
0.5
1.0
1.5
2.0
2.5
0
10
20
30
40
50
60
70
80
90
100
Reference and actual EEDICO2 emissionsgram per dwt/n mile
Actual/ReferenceEEDI %
3.0
2013Year
Contract datebefore 1 January
2015
2020
2025
92%88%
86%
EEDI actualEEDI reference (2.81/100%)
94%
75% SMCR: 14.5 kn without sea margin
Fig. 8: Reference and actual Energy Efficiency Design Index (EEDI) for 14.7 knots
2
30
40
50
4
6
60
70
8
10
12
14
Relative saving of fuel consumption
%
Fuel consumptionof main engine
t/24h
IMO Tier llISO ambient conditions
LCV = 42,700 kJ/kg
0
10
20
0
Dprop:
63.23t/24h
6S70ME-C8.5N1
8.2 m × 4
0%
62.10t/24h
6S70ME-C8.5N2
8.7 m × 4
1.8%
59.36t/24h
6G70ME-C9.5N3
8.7 m × 4
6.1%
58.06t/24h
6G70ME-C9.5N4
9.3 m × 4
8.2%
Fig. 7: Expected fuel consumption at NCR = 90% SMCR for 14.7 knots
The reference and the actual EEDI
figures have been calculated and
are shown in Fig. 8 (EEDIref = 961.8 x
dwt -0.477, 15 July 2011). As can be seen
for all four cases, the actual EEDI fig-
ures are relatively high with the lowest
EEDI (86%) for case 4 with 6G70ME-
C9.5. Cases 3 and 4 with 6G70ME-
C9.5 are the only ones to meet the
2015 reference EEDI.
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%.
12 Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
After some years in service, the rela-
tive savings in operating costs in Net
Present Value (NPV), see Fig. 10, with
the existing 6S70ME-C8.5 used as
basis with the propeller diameter of
about 8.2 m, indicates an NPV saving
for the new 6G70ME-C9.5 engines.
After 25 years in operation, the saving
is about 15.9 million USD for N4 with
6G70ME-C9.5 with the SMCR speed
of 71.0 r/min and propeller diameter of
about 9.3 m.
Fig. 9: Total annual main engine operating costs for 14.7 knots
0
2.0
4.0
6.0
1.0
3.0
5.0
Annual operating costsMillion USD/Year
Relative saving in operating costs
%
Dprop:
7.0
8.0
9.0
10.0
11.0
12.0
0
2
4
6
1
3
5
7
8
9
10
11
12
6S70ME-C8.5N1
8.2 m × 4
6S70ME-C8.5N2
8.7 m × 4
6G70ME-C9.5N3
8.7 m × 4
6G70ME-C9.5N4
9.3 m × 4
0%1.8%
6.0%
8.0%
MaintenanceLubricating oil
Fuel oil
IMO Tier llISO ambient conditions
250 days/yearNCR = 90% SMCR
Fuel price: 700 USD/t
YearsLifetime
0
4
2
6
0 5 10 15 20 25 30
8
10
12
14
16
18
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.
N2: 8.7 m × 46S70ME-C8.5
N3: 8.7 m × 46G70ME-C9.5
N4: 9.3 m × 46G70ME-C9.5
N1: 8.2 m × 4 Basis6S70ME-C8.5
Fig. 10: Relative saving in main engine operating costs (NPV) for 14.7 knots
13Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
0
4,000
6,000
2,000
8,000
12,000
14,000
10,000
Relative powerreduction
%
Propulsion power demand at N’ = NCR
kW
0
1
2
3
4
5
6
7
Dprop:
Inclusive of sea margin = 15%
6S70ME-C8.5N1’
8.3 m × 4
13,671 kW
0%
5G70ME-C9.5N2’
8.8 m × 4
13,248 kW
3.1%
5G70ME-C9.5N3’
9.3 m × 4
12,834 kW
6.1%
6G70ME-C9.5N4’
9.3 m × 4
12,834 kW
6.1%
Fig. 11: Expected propulsion power demand at NCR = 90% SMCR for 14.0 knots
Main Engine Operating Costs – 14.0 knots
The calculated main engine examples
are as follows:
14.0 knots
1’. 6S70ME-C8.5 (Dprop = 8.3 m)
M1’ = 15,190 kW × 84.0 r/min
2’. 5G70ME-C9.5 (Dprop = 8.8 m)
M2’ = 14,720 kW × 75.0 r/min.
3’. 5G70ME-C9.5 (Dprop = 9.3 m)
M3’ = 14,260 kW × 67.0 r/min.
4’. 6G70ME-C9.5 (Dprop = 9.3 m)
M4’ = 14,260 kW × 67.0 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 lower ship
speed of 14.0 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). Examples 3’ and 4’ indicate the in-
fluence of one extra engine cylinder.
Fuel consumption and EEDI
Fig. 11 shows the influence of the
propeller diameter with four propeller
blades when going from about 8.3 m to
9.3 m. Thus, N3’ and N4’ for the 5 and
6G70ME-C9.5 with an about 9.3 m pro-
peller diameter has a propulsion power
demand that is about 6.1% lower com-
pared with the N1’ for the 6S70ME-C8.5
with an about 8.3 m propeller diameter.
14 Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Engine shaft power
171
172
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100% SMCR154
155
156
157
158
159
160
161
162
163
164
165
166
167
SFOCg/kWh
168
169
170
IMO Tier llISO ambient conditionsLCV = 42,700 kJ/kg
Standard high-loadoptimised engines
M’ = SMCRN’ = NCR
N1’
N3’
N2’
N4’
M3’ 5G70ME-C9.5 9.3 m ×4
M1’ 6S70ME-C8.5 8.3 m ×4M2’ 5G70ME-C9.5 8.8 m ×4
M4’ 6G70ME-C9.5 9.3 m ×4
Dprop
Savings in SFOC
0.0%Basis
-1.2%
0.2%
1.8%
Fig. 12: Expected SFOC for 14.0 knots
Fig. 12 shows the influence on the main
engine efficiency, indicated by the Spe-
cific Fuel Oil Consumption, SFOC, for
the four cases. N3’ = 90% M3’ with
the 5G70ME-C9.5 has a relatively high
SFOC of 163.9 g/kWh compared with
the 162.0 g/kWh for N1’ = 90% M1’
for the 6S70ME-C8.5, i.e. an SFOC in-
crease of about 1.2%, mainly caused
by the greater speed derating potential
giving higher mep of the 5G70ME-C9.5
engine type, but involving a higher po-
tential propeller efficiency. However,
for N4’ = 90% M4’ (in the same point
as for N3’) for the 6G70ME-C9.5, the
mep derating involves a lower SFOC
of 159.1 g/kWh corresponding to an
SFOC reduction of 1.8%.
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 6G70ME-
C9.5, N4’ with propeller diameter 9.3 m,
is about 7.8% compared with the exist-
ing 6S70ME-C8.5 (see also the above-
mentioned savings of 6.1% and 1.8%).
15Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
1
2
3
4
5
6
7
8
9
10
Relative saving of fuel consumption
%
Fuel consumptionof main engine
t/24h
IMO Tier llISO ambient conditions
LCV = 42,700 kJ/kg
0
10
15
20
25
30
35
40
45
50
60
55
06S70ME-C8.5
N1’8.3 m × 4Dprop:
53.15t/24h
0%
5G70ME-C9.5N2’
8.8 m × 4
51.40t/24h
3.3%
5G70ME-C9.5N3’
9.3 m × 4
50.50t/24h
5.0%
6G70ME-C9.5N4’
9.3 m × 4
49.00t/24h
7.8%
Dprop:
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
10
20
30
40
50
60
70
80
90
100
110
120
Reference and actual EEDICO2 emissionsgram per dwt/n mile
Actual/ReferenceEEDI %
2013Year
Contract datebefore 1 January
2015
2020
2025
EEDI actualEEDI reference (2.81/100%)
5G70ME-C9.5N2’
8.8 m × 4
80%2.26
5G70ME-C9.5N3’
9.3 m × 4
79%2.22
6G70ME-C9.5N4’
9.3 m × 4
77%
2.16
6S70ME-C8.5N1’
8.3 m × 4
83%2.34
75% SMCR: 13.8 kn without sea margin
Fig. 14: Reference and actual Energy Efficiency Design Index (EEDI) for 14.0 knots
Fig. 13: Expected fuel consumption at NCR = 90% SMCR for 14.0 knots
The reference and the actual EEDI
figures have been calculated and are
shown in Fig. 14 (EEDIref = 961.8 ×
dwt -0.477, 15 July 2011). As can be seen
for all four cases, the actual EEDI fig-
ures are now somewhat lower than
the reference figure because of the
relatively low ship speed of 14.0 knots.
Particularly, case 4’ with 6G70ME-C9.5
has a low EEDI – about 77% of the
2013 reference figure. All G70ME-C9.5
engine cases will meet the stricter 2020
EEDI reference figure.
16 Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
0
1
2
3
4
5
6
7
8
9
Annual operating costsMillion USD/Year
Relative saving in operating costs
%
Dprop:
10
0
1
2
3
4
5
6
7
8
9
10
6S70ME-C8.5N1’
8.3 m × 4
0%
5G70ME-C9.5N2’
8.8 m × 4
3.5%
6G70ME-C9.5N4’
9.3 m × 4
7.6%
5G70ME-C9.5N3’
9.3 m × 4
5.2%
MaintenanceLub. oil
Fuel oil
IMO Tier llISO ambient conditions
250 days/yearNCR = 90% SMCR
Fuel price: 700 USD/t
Fig. 15: Total annual main engine operating costs for 14.0 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 relative
savings in operating costs in Net Present
Value, NPV, see Fig. 16, with the existing
6S70ME-C8.5 with the propeller diam-
eter of about 8.3 m used as basis, indi-
cates an NPV saving after some years in
service for the new 5 and 6G70ME-C9.5
engines. After 25 years in operation, the
saving is about 12.8 million USD for N4’
with the 6G70ME-C9.5 with the SMCR
speed of 67.0 r/min and propeller diam-
eter of about 9.3 m.
LifetimeYears
0
5
3
7
12
14
15
13
11
9
8
6
4
2
1
10
0 5 10 15 20 25 30
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.
N2’: 8.8 m × 45G70ME-C9.5
N3’: 9.3 m × 45G70ME-C9.5
N4’: 9.3 m × 46G70ME-C9.5
N1’: 8.3 m × 46S70ME-C8.5
Fig. 16: Relative saving in main engine operating costs (NPV) for 14.0 knots
17Propulsion of 200,000-210,000 dwt Large Capesize Bulk Carrier
Summary
Traditionally, super long stroke S-type
engines, with relatively low engine
speeds, have been applied as prime
movers in bulk carriers.
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 bulk carriers
and tankers.
Large bulk carriers and tankers may be
compatible with propellers with larger
propeller diameters than the current
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.
Even in cases where an increased size
of the propeller is limited, the use of
propellers based on the new propeller
technology will be an advantage.
The new and ultra long stroke G70ME-
C9.5 engine type meets this trend in the
large bulk carrier and tanker market. This
paper indicates, depending on the pro-
peller diameter used, an overall efficiency
increase of 3-8% when using G70ME-
C9.5, compared with the existing main
engine type S70ME-C8.5 applied so far.
The Energy Efficiency Design Index
(EEDI) will also be reduced when us-
ing G70ME-C9.5. 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 200,000-210,000 dwt Large Capesize Bulk Carrier
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. 5510-0146-00ppr Feb 2014 Printed in Denmark