Propulsion of 7,000-10,000 dwt Small tanker

Propulsion of 7,000-10,000 dwtSmall 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

8,000 dwt small tanker ...........................................................................9

Main Engine Operating Costs – 14.0 knots ................................................. 10

Fuel consumption and EEDI .................................................................. 10

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

Main Engine Operating Costs – 13.0 knots ................................................. 14

Fuel consumption and EEDI .................................................................. 14

Operating costs .................................................................................... 17

Summary ................................................................................................... 18

Propulsion of 7,000-10,000 dwt Small Tanker

Introduction

The main ship particulars of 7,000-

10,000 dwt small tankers are normally

approximately as follows: the overall

ship length is 116 m, breadth 18 m and

scantling draught 7.0-8.0 m, see Fig. 1.

Recent development steps have made

it possible to offer solutions which will

enable significantly lower transporta-

tion costs for small 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 Rat-

ing (NCR), including 15% sea margin,

used to be as high as 14.0 knots. Today,

the ship speed may be expected to be

lower, possibly 13 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. 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: Small tanker

5Propulsion of 7,000-10,000 dwt Small Tanker

As the two-stroke main engine is di-

rectly coupled with the propeller, the

introduction of the super long stroke

S30ME-B9.3 engine with even lower

than usual shaft speed will meet this

goal. The main dimensions for this en-

gine type, and for the existing small-

size tanker (and bulk carrier) engine

L35MC6.1, are shown in Fig. 2.

On the basis of a case study of an 8,000

dwt small tanker in compliance with

IMO Tier II emission rules, this paper

shows the influence on fuel consump-

tion when choosing the new S30ME-B

engine compared with the old and nor-

mally used L35MC6 engine. The layout

ranges of 5 and 6S30ME-B9.3 engines

compared with 5 and 6L35MC6.1 to-

gether with the 5S35ME-B9.3 are

shown later in Fig. 5.

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 ba-

sis of maximum cargo capacity (70%

for container ships), propulsion power,

ship speed, SFOC (Specific Fuel Oil

Consumption) and fuel type. Depend-

5,08

4

1,980

1,01

0 460

5,58

6

1,942

1,05

8 345

L35MC6.1S30ME-B9.3

Fig. 2: Main dimensions for the new S30ME-B9.3 engine and the old L35MC6.1 applied earlier

ing on the date of contract, the EEDI

is required to be a certain percentage

lower than an IMO defined reference

value depending on the type and ca-

pacity of the ship.

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 com-

pared to a reference value. Thus, a ship

bigger than 20,000 dwt and built after

2025 is required to have a 30% lower

EEDI than the 2013 reference figure.

6 Propulsion of 7,000-10,000 dwt Small Tanker

Fig. 4: Influence of propeller diameter and pitch on SMCR for an 8,000 dwt small tanker operating at

14.0 knots

Fig. 3: EEDI reference requirements in the future valid for tankers

For ships smaller than 4,000 dwt, there

are no lower limitation demands. For

the 8,000 dwt small tanker in question,

the EEDI reference value required af-

ter 2025 will be 7.5% lower, i.e. equal

to 92.5% of the 2013 reference EEDI

value, see Fig. 3.

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 an

8,000 dwt small tanker with a service

ship speed of 14 knots, see the black

curve in Fig. 4. The needed propulsion

SMCR (Specified Maximum Continu-

ous 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 3.5 m may

have the optimum pitch/diameter ratio

of 0.72, and the lowest possible SMCR

shaft power of about 3,625 kW at about

219 r/min.

The black curve shows that if a bigger

propeller diameter of 3.9 m is possible,

the necessary SMCR shaft power will

be reduced to about 3,425 kW at about

179 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.

3,000

3,600

3,700

3,800

3,900

3,100

3,200

3,300

3,400

3,500

4,000

130 140 150 160 170 180 190 200 210 220 r/minEngine/propeller speed at SMCR

PropulsionSMCR power

kW

L35MC6.1

Power and speed curve for the given propeller diameter d = 3.9 m with different p/d ratiosPower 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 = 14.0 knDesign Draught = 7.1 m

S30ME-B9.3

S30ME-B9.3

L35MC6.1

1.050.95

0.85

0.77

0.74

0.72

3.9 m

4.3 m

3.5 mp/dd

0.650.60

0.55p/d

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2013 2015 2020 2025

EEDI reference value

Year

Tanker <4,000 dwt Tanker = 8,000 dwt Tanker >20,000 dwt

100% 100% 100% 100%100%97.5%

95.0%92.5%

100%

90%

80%

70%


6S30ME-B9.35S35ME-B9.3

6L35MC6.1

5L35MC6.1

5S30ME-B9.3

0

1,000

2,000

3,000

4,000

5,000

6,000

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 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 margin10% engine margin5% light running

Tdes = 7.10 m

S30ME-B9.3Bore = 300 mmStroke = 1,328 mmVpist = 8.63 m/sS/B = 4.427MEP = 21 barL1 = 640 kW × 195 r/min

M = SMCR (14.0 kn)M1 = 3,585 kW × 210 r/min, 6L35MC6.1M2 = 3,510 kW × 195 r/min, 6S30ME-B9.3M3 = 3,395 kW × 173 r/min, 6S30ME-B9.3

M’ = SMCR (13.0 kn)M1’ = 2,710 kW × 210 r/min, 5L35MC6.1M2’ = 2,655 kW × 195 r/min, 5S30ME-B9.3M3’ = 2,540 kW × 166 r/min, 5S30ME-B9.3

PossibleDprop=4.3 m(= 60.6% of Tdes)

PossibleDprop=3.9 m(= 54.9% of Tdes)

ExistingDprop=3.5 m(= 49.3% of Tdes)

14.0 kn

13.0 kn

12.0 kn

15.0 kn

∝

∝

∝

∝

210 r/min195 r/min

167 r/min

M1

M1’

M2M3

M2’

M3’

Increased propeller diameter – S30ME-B9.3

Fig. 5: Different main engine and propeller layouts and SMCR possibilities (M1, M2, M3 for 14.0 knots and M1’, M2’, M3’ for 13.0 knots) for an 8,000 dwt small

tanker operating at 14.0 knots and 13.0 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 a super long stroke en-

gine type, as the S30ME-B9.3, may

have a higher efficiency compared with

a shorter stroke engine type, like an

L35MC6.1.

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

S30ME-B9.3 engine can be utilised

also in case a correspondingly larger

propeller cannot be accommodated.


8,000 dwt small tanker

For an 8,000 dwt small tanker, the fol-

lowing case study illustrates the poten-

tial for reducing fuel consumption by

increasing the propeller diameter and

introducing the S30ME-B9.3 as main

engine. The ship particulars assumed

are as follows:

Scantling draught m 7.5

Design draught m 7.1

Length overall m 116.0

Length between pp m 110.0

Breadth m 18.0

Sea margin % 15

Engine margin % 10

Design ship speed kn 14.0 and 13.0

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 small tanker is found,

see Fig. 5. The propeller diameter

change corresponds approximately to

the constant ship speed factor α = 0.28

[ref. PM2 = PM1 × (n2/n1)α.

Referring to the two ship speeds of

14.0 knots and 13.0 knots, respective-

ly, three potential main engine types,

pertaining layout diagrams and SMCR

points have been drawn-in in Fig. 5,

and the main engine operating costs

have been calculated and described.

The L35MC6.1 engine type (210 r/

min) has often been used in the past

as prime movers in projects for small

tankers. Therefore, a comparison be-

tween the new S30ME-B9.3 and the

old L35MC6.1 is of major interest in

this paper.

In this connection, the existing

5S35ME-B9.3 seems to have the ideal

low engine speed, however powerwise,

it is too big.

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.


0

1,000

1,500

500

2,000

3,000

2,500

3,500

Relative powerreduction

%

Propulsion power demand at N = NCR

kW

0

1

2

3

4

5

6

7

6L35MC6.1N1

3.6 m × 4

6S30ME-B9.3N2

3.7 m × 4

6S30ME-B9.3N3

4.0 m × 4Dprop:

3,227 kW

Inclusive of sea margin = 15%

3,159 kW3,056 kW

0%

2.1%

5.3%

Fig. 6: 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. 6L35MC6.1 (Dprop = 3.6 m)

M1 = 3,585 kW × 210.0 r/min

2. 6S30ME-B9.3 (Dprop = 3.7 m)

M2 = 3,510 kW × 195.0 r/min.

3. 6S30ME-B9.3 (Dprop = 4.0 m)

M3 = 3,395 kW × 173.0 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 14.0 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. 6 shows the influence of the pro-

peller diameter with four propeller

blades when going from about 3.6 m to

4.0 m. Thus, N3 for the 6S30ME-B9.3

with a 4.0 m propeller diameter has a

propulsion power demand that is about

5.3% lower compared with N1 valid for

the 6L35MC6.1 with a propeller diam-

eter of about 3.6 m.


Fig. 7 shows the influence on the main

engine efficiency, indicated by the Spe-

cific Fuel Oil Consumption, SFOC, for

the three cases. For N3 = 90% M3 with

the 6S30ME-B9.3 SFOC is 174.9 g/

kWh, for N2 = 90% M2 with 6S30ME-

B9.3 SFOC is 173.3 g/kWh and for N1

= 90% M1 with 6L35MC6.1 SFOC is

175.8 g/kWh. In all cases for the ME-B

engines, +1 g/kWh needed for the Hy-

draulic Power Supply (HPS) system

is included. In N2, the SFOC is about

1.4% lower compared with N1.

All ME-B9.3 engine types are as stand-

ard fitted with VET (Variable Exhaust

valve Timing) reducing the SFOC at

part operation.

When multiplying the propulsion power

demand at N (Fig. 6) with the SFOC

(Fig. 7), the daily fuel consumption is

found and is shown in Fig. 8. Compared

with N1 for the old 6L35MC6.1, the to-

tal reduction of fuel consumption of the

new 6S30ME-B9.3 at N3 is about 5.7%

(see also the above-mentioned savings

of 5.3% and 0.5%).

Engine shaft power

189

190

191

25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100% SMCR171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

SFOCg/kWh

186

187

188

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

Standard high-loadoptimised engines

ME-B9.3 is with VET = Variable Exhaust valve Timing

For ME-B engines, the fuel consumption (+1g/kWh) for HPS is included.

M = SMCRN = NCR

N1

N3

N2

M1 6L35MC6.1M3 6S30ME-B9.3

M2 6S30ME-B9.3 3.7 m ×4

3.6 m ×44.0 m ×4

Dprop

Savings in SFOC

0.5%0.0%

1.4%

Fig. 7: Expected SFOC for 14.0 knots


0

2

4

6

8

10

12

14

18

20

16

0

10

20

30

40

50

60

70

80

90

100

110

120

130

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

EEDI actualEEDI reference

Dprop:

6L35MC6.1N1

3.6 m × 4

6S30ME-B9.3N2

3.7 m × 4

15.18 15.57

103%15.18 15.38

101%

6S30ME-B9.3N3

4.0 m × 4

15.1814.64

96%

75% SMCR: 13.8 kn without sea margin

Fig. 9: Reference and actual Energy Efficiency Design Index (EEDI) for 14.0 knots

123

54567

10

89

15

101112131415

Relative saving of fuel consumption

%

Fuel consumptionof main engine

t/24h

IMO Tier llISO ambient conditions

LCV = 42,700 kJ/kg

0 0

13.61t/24h

0%

13.14t/24h

3.5%

12.83t/24h

5.7%

6L35MC6.1N1

3.6 m × 4

6S30ME-B9.3N2

3.7 m × 4

6S30ME-B9.3N3

4.0 m × 4Dprop:

For ME-B engines, the fuel consumption for HPS is included.

Fig. 8: 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. 9 (EEDIref = 1,218.8 x

dwt -0.488, 15 July 2011). As can be seen

for all three cases, the actual EEDI fig-

ures are relatively high with the lowest

EEDI (96%) for case 3 with 6S30ME-

B9.3. Case 3 is the only one to meet

the 2013 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. 10.

The lube oil and maintenance costs are

shown too. As can be seen, the major

operating costs originate from the fuel

costs – about 95%.


After some years in service, the rela-

tive savings in operating costs in Net

Present Value (NPV), see Fig. 11,

with the old 6L35MC6.1 used as ba-

sis with the propeller diameter of

about 3.6 m, indicates an NPV saving

for the new 6S30ME-B9.3 engines.

After 25 years in operation, the saving

is about 2.7 million USD for N3 with

6S30ME-B9.3 with the SMCR speed of

173.0 r/min and propeller diameter of

about 4.0 m.

Fig. 10: Total annual main engine operating costs for 14.0 knots

0

1.0

2.0

3.0

0.5

1.5

2.5

6L35MC6.1N1

3.6 m × 4

6S30ME-B9.3N2

3.7 m × 4

6S30ME-B9.3N3

4.0 m × 4

0

4

8

2

6

101112

1

5

9

3

7

Annual operating costsMillion USD/Year

Relative saving in operating costs

%

Dprop:

0%

3.9%

6.1%

MaintenanceLub. oil

Fuel oil


250 days/yearNCR = 90% SMCR

Fuel price: 700 USD/t

Fig. 11: Relative saving in main engine operating costs (NPV) for 14.0 knots


0

1,000

1,500

500

2,000

3,000

2,500

Relative powerreduction

%

Propulsion power demand at N = NCR

kW

0

2

4

6

8

10

12

1

3

5

7

9

11

5L35MC6.1N1’

3.3 m × 4

5S30ME-B9.3N2’

3.5 m × 4

5S30ME-B9.3N3’

3.8 m × 4Dprop:

2,439 kW

Inclusive of sea margin = 15%

2,390 kW2,286 kW

0%

2.0%

6.3%

Fig. 12: Expected propulsion power demand at NCR = 90% SMCR for 13.0 knots

Main Engine Operating Costs – 13.0 knots

The calculated main engine examples

are as follows:

13.0 knots

1’. 5L35MC6.1 (Dprop = 3.3 m)

M1’ = 2,710 kW × 210.0 r/min

2’. 5S30ME-B9.3 (Dprop = 3.5 m)

M2’ = 2,655 kW × 195.0 r/min.

3’. 5S30ME-B9.3 (Dprop = 3.8 m)

M3’ = 2,540 kW × 166.0 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 13.0 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).

Fuel consumption and EEDI

Fig. 12 shows the influence of the

propeller diameter with four propeller

blades when going from about 3.3 m to

3.8 m. Thus, N3’ for the 5S30ME-B9.3

with an about 3.8 m propeller diameter

has a propulsion power demand that is

about 6.3% lower compared with the

N1’ for the 6L35MC6.1 with an about

3.3 m propeller diameter. For the two

ME-B engine cases, an extra SFOC of

+1 g/kWh has been added correspond-

ing to the power demand needed for the

Hydraulic Power Supply (HPS) system.


Engine shaft power

187

188

189

25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100% SMCR

190

170

171

172

173

174

175

176

177

178

179

180

181

182

183

SFOCg/kWh

184

185

186

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

Standard high-loadoptimised engines

ME-B9.3 is with VET = Variable Exhaust valve Timing

For ME-B engines, the fuel consumption (+1g/kWh) for HPS is included.

M’ = SMCRN’ = NCR

N1’

N3’

N2’

M1’ 5L35MC6.1M3’ 5S30ME-B9.3

M2’ 5S30ME-B9.3 3.5 m ×4

3.3 m ×43.8 m ×4

Dprop

Savings in SFOC

0.2%0.0%

1.4%

Fig. 13: Expected SFOC for 13.0 knots

Fig. 13 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 5S30ME-B9.3 has a relatively high

SFOC of 173.7 g/kWh compared with

the 174.1 g/kWh for N1’ = 90% M1’ for

the 6L35MC6.1, i.e. an SFOC reduc-

tion of only about 0.2%, mainly caused

by the greater speed derating potential

giving higher mep of the 5S30ME-B9.3

engine type, but involving a higher po-

tential propeller efficiency.

The daily fuel consumption is found by

multiplying the propulsion power de-

mand at N’ (Fig. 12) with the SFOC (Fig.

13), see Fig. 14. The total reduction of

fuel consumption of the new 5S30ME-

B9.3, N3’ with propeller diameter 3.8 m,

is about 6.6% compared with the old

5L35MC6.1 (see also the above-men-

tioned savings of 6.3% and 0.2%).


1

2

3

4

5

6

7

8

9

11

10

Relative saving of fuel consumption

%

Fuel consumptionof main engine

t/24h


LCV = 42,700 kJ/kg

0

1

2

3

4

5

6

7

8

9

11

10

05L35MC6.1

N1’3.3 m × 4

5S30ME-B9.3N2’

3.5 m × 4

5S30ME-B9.3N3’

3.8 m × 4Dprop:

For ME-B engines, the fuel consumption for HPS is included.

10.19t/24h

0%

9.84t/24h

3.4%

9.52t/24h

6.6%

0

2

4

6

8

10

12

14

18

20

16

0

10

20

30

40

50

60

70

80

90

100

110

120

130

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

EEDI reference EEDI actual

Dprop:

5L35MC6.1N1’

3.3 m × 4

15.18

12.57

83%

5S30ME-B9.3N2’

3.5 m × 4

15.18

12.12

80%

5S30ME-B9.3N3’

3.8 m × 4

15.18

11.73

77%

75% SMCR: 12.8 kn without sea margin

Fig. 15: Reference and actual Energy Efficiency Design Index (EEDI) for 13.0 knots

Fig. 14: Expected fuel consumption at NCR = 90% SMCR for 13.0 knots

The reference and the actual EEDI

figures have been calculated and are

shown in Fig. 15 (EEDIref = 1,218.8 ×

dwt -0.488, 15 July 2011). As can be seen

for all three cases, the actual EEDI fig-

ures are now somewhat lower than the

reference figure because of the relative-

ly low ship speed of 13.0 knots. Partic-

ularly, case 3’ with 5S30ME-B9.3 has

a low EEDI – about 77% of the 2013

reference figure. All engine cases will

meet the stricter 2025 EEDI reference

figures.


0

1.0

2.0

0.5

1.5

0

8

16

4

12

2

10

6

14

Annual operating costsMillion USD/Year

Relative saving in operating costs

%

Dprop:

5L35MC6.1N1’

3.3 m × 4

0%

5S30ME-B9.3N2’

3.5 m × 4

3.9%

5S30ME-B9.3N3’

3.8 m × 4

7.0%

MaintenanceLub. oil

Fuel oil


250 days/yearNCR = 90% SMCR

Fuel price: 700 USD/t

Fig. 16: Total annual main engine operating costs for 13.0 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. 16.

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 95%.

After some years in service, the rela-

tive savings in operating costs in Net

Present Value, NPV, see Fig. 17, with

the old 5L35MC6.1 with the propeller

diameter of about 3.3 m used as ba-

sis, indicates an NPV saving after some

years in service for the new 5S30ME-

B9.3 engine. After 25 years in opera-

tion, the saving is about 2.3 million USD

for N3’ with the 5S30ME-B9.3 with the

SMCR speed of 166.0 r/min and pro-

peller diameter of about 3.8 m.

LifetimeYears

0

–1

2

1

3

0 5 10 15 20 25 30

4

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’: 3.5 m × 45S30ME-B9.3

N3’: 3.8 m × 45S30ME-B9.3

N1’: 3.3 m × 45L35MC6.1

Fig. 17: Relative saving in main engine operating costs (NPV) for 13.0 knots


Summary

Traditionally, long stroke L-type en-

gines, with relatively high engine

speeds, have been applied as prime

movers in very small 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 small tankers

and bulk carriers.

Small tankers and bulk carriers 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.

The new and small super long stroke

S30ME-B9.3 engine type meets this

trend in the small tanker and bulk

carrier market. This paper indicates,

depending on the propeller diameter

used, an overall efficiency increase of

3-7% when using S30ME-B9.3, com-

pared with the old main engine type

L35MC6.1 applied so far.

The Energy Efficiency Design Index

(EEDI) will also be reduced when us-

ing S30ME-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.


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. 5510-0144-00web Aug 2013 Printed in Denmark

Propulsion of 7,000-10,000 dwt Small tanker

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