improving the efficiency of small inland vessels · with the cooperation of the belgian federal...

European Inland Waterway Navigation Conference

10-11 June, 2010, Baja, Hungary

1

Improving the efficiency of small inland vessels

Stefan GEERTS1, Bart VERWERFT

2, Marc VANTORRE

3

Maritime Technology Division, IR15, Ghent University

Technologiepark 904, 9052 GENT, Belgium

Frans VAN ROMPUY

Belgian Federal Public Service Mobility and Transport

Vooruitgangstraat 56, 1210 BRUSSEL, Belgium

ABSTRACT

On behalf of the Belgian Federal Public Service Mobility and Transport, the Maritime Technology Division of Ghent

University had performed a scientific investigation to assess potential technical measures to increase the energy efficiency of

inland vessels, and the costs and benefits – including environmental aspects – resulting from these measures. The results of

this study can be applied to the design or reconversion of inland vessels to reduce the energy consumption and emission of

greenhouse gases and noxious materials.

The study consists of a literature study, an analysis of the present inland vessel fleet, and the study of available data

concerning resistance and propulsion, to determine measures that can lead to an optimization of the design of an inland vessel

by:

Reducing the hull resistance;

Increasing the hydrodynamic efficiency of the propeller by improving the design and selection of an optimal

propeller;

Increasing the efficiency of the engine;

Any other measures (e.g. control devices)

A cost-benefit analysis is carried out by quantifying which financial and environmental advantages can potentially be realized

by the considered measures, and by assessing the additional cost due to investments and the loss of cargo capacity.

This analysis only focuses on smaller types of inland vessels (250 – 1350 ton) sailing on the Belgian waterways. Three types

of inland ships can be identified in this loading capacity range, the péniche-spits, the Campine barge and Rhine-Herne-Canal

ships. The average yearly fuel consumption and emissions are estimated for these three classes of ships, taking into account

the operational profile on each of the classes of Belgian waterways.

Several possibilities for reduction of fuel consumption and emissions are investigated. Measures that reduce the ship’s

resistance can have a beneficial effect on fuel consumption and emission reduction on the Belgian waterways when mainly

the viscous or frictional resistance is reduced. A reduction of wave making resistance is less beneficial due to the low forward

speed in confined waters. Only in the case of small inland ships travelling great distance on open water, a large impact in fuel

consumption and emissions can be detected if the wave making resistance is reduced.

Optimization of the propeller and/or the installation of a propeller nozzle may induce a large gain in thrust and performance,

especially on the older small inland ships, since they have originally been designed for towed operation.

Technical developments aside, it is very important that the skipper is aware of fuel consumption at all time since it is a real-

time indication of efficiency. It is therefore recommended to install a fuel consumption indicator on existing small ships. A

very important lesson to learn is that all investment in a resistance reducing, or efficiency increasing measure is mainly

turned into a greater forward speed and a reduction in travel time and not into a reduction of fuel cost and emissions when no

change is made to the operational profile.

Keywords: inland navigation, sustainable transport, efficiency increase, emission

1 [email protected]

2 [email protected]

3 [email protected]



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1. Introduction

In December 2008, the Belgian Federal Public Service Mobility and Transport commissioned Ghent

University to investigate potential ways of increasing the efficiency of certain inland waterway vessels.

The main goal of the project is to determine possible technical measures to improve the energy

efficiency of transportation of goods by inland waterway vessel through scientific research and the

costs and benefits, including ecological benefits, of these measures.

When building or reconverting a vessel, it is possible to take into account the results of this study to

improve the efficiency and to reduce the emission of dangerous materials and greenhouse gasses.

This study consists of two parts:

A scientific analysis (literature study, analysis of the inland fleet, re-analysis of previous

measurements on vessels, etc) of possible measures that increase efficiency and reduce

noxious emissions in the inland fleet by reviewing how the design can be optimized to:

o reduce the resistance (hull design)

o increase the efficiency of the propeller (increase the hydrodynamic efficiency of the

propeller by optimizing the design and main dimensions)

o increase the efficiency of the engine (increase thermal efficiency)

o decrease fuel consumption and emissions in any other way …

For all measures found in the first section, a costs-benefits analysis is performed by

quantifying which financial and ecological gain can be obtained and what the increased

investment will be for the ship owner.

This study is limited to the following ship types:

S Spits – Péniche 250 – 400 ton Class I

K Kempenaar – Campine Barge 400 – 650 ton Class II

R Rhine-Herne Canal Ship max 1350 ton Class IV

2. Case Description

To be able to predict possible changes in resistance, one needs to estimate the power required to propel

the craft and quantify the influence of the waterway since the power needed to advance an inland ship

strongly depends on waterway characteristics.

Firstly, the ship characteristics will be discussed, next the waterway geometry and the use of the

different classes of waterways by every ship type, and finally power prediction and emissions.

2.1 Ship characteristics

As mentioned before, the study presented here only considers the following small inland ship types

(classes I, II and IV). A list of all Belgian inland ships considered in the above categories is obtained

with the cooperation of the Belgian Federal Public Service Mobility and Transport, Shipping

Inspectorate, Inland Shipping. The fleet consists of 167 Péniche, 103 Campine barges and 266 Rhine-

Herne Canal Ships. The greater part of these vessels is built between 1950 and 1970 as can be seen in

Figure 1.



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Date of Construction and loading capacity for the Belgian inland ships

0

200

400

600

800

1,000

1,200

1,400

1,600

1909

1919

1929

1939

1949

1959

1969

1979

1989

1999

2010

Date of Construction

Lo

ad

ing

Cap

acit

y (

ton

)Péniche

Campine Barge

Rhine-Herne Canal Ship

Fig. 1 Date of construction and loading capacity of Belgian inland ships under 1350 ton (based on 2009 database of

Belgian Federal Public Service Mobility and Transport)

Based on the statistics of the ships in the list above, a characteristic ship for each of the three classes is

chosen for analysis. The “Picaro”, the “Prima” and the “Adriaan” can be taken to be representatives of

their respective classes, being Péniche, Campine Barge and Rhine-Herne Canal Ship. For

the”Adriaan”, reference is made to Waterloopkundig Laboratorium (1974). The next figure represents

the loading capacity and engine power of all ships including the ships mentioned above and the

average value. Figure 3 shows the average values and the characteristics of the representative ships.

0

200

400

600

800

1,000

1,200

0

20

0

40

0

600

80

0

10

00

12

00

140

0

Loading Capacity (ton)

En

gin

e P

ow

er

(kW

)

Péniche

Campine Barge

Rhine-Herne Canal Ships

"Picaro"

"Prima"

"Adriaan"

Rhine-Herne Averaged

Campine Averaged

Rhine-Herne Averaged

Fig. 2 Loading capacity versus engine power of Belgian inland ships under 1350 ton (based on 2009 database of

Belgian Federal Public Service Mobility and Transport)



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Tab. 1 Overview of example ships

S K R

Average Loading Capacity (tons) 360 tons 550 tons 1005 tons

Average Engine Power (kW) 215 kW 290 kW 520 kW

Example Ship “Picaro” “Prima” “Adriaan”

Loading Capacity (tons) 368 tons 600 tons 1100 tons

Engine Power (kW) 265 kW 300 kW Unknown

2.2 Waterway data

The Belgian waterway system can be divided following the European C.E.M.T. classification system.

Only waterways of classes I, II, IV, V and VI are present in Belgium. This classification is mainly

based on ship dimensions and to a lesser extent on loading capacity. An overview of these waterways

is important since resistance and therefore also emissions, depends to a great extent on waterway

dimensions.

The present classification of waterways is not sufficient to capture the influence of waterway depth

and breadth, since some canals of the same class do not necessarily have the same dimensions.

Comparing the canal docks in the Port of Antwerp with the Albert Canal, it is easy to see that even

though they are both off class VI, the influence on the inland ship cannot be taken as equal. For this

reason, a separate waterways class “Z” has been introduced, indication waterways suited for sea-going

ships. In Figure 3, an overview of the navigable waterways in Belgium is given.

Fig. 3 Belgian navigable waterway system (Promotie Binnenvaart Vlaanderen, 2009)

2.3 Waterway usage

Since the Belgian waterway system is administered by six different agencies, it is very difficult to get

consistent statistical data about usage. Detailed information about loaded and unloaded voyages is

difficult to obtain since every administration keeps different kinds of statistics.

In Tables 2 and 3, the usage of the waterways by the three types of ships is presented for loaded and

unloaded voyages in 2007, based on statistics published by the various waterways authorities.



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Tab. 2 Statistics on loaded voyages on Belgian waterways in 2007 [Million ton km]

Ship type by loading capacity (ton)

< 400

S

401 – 650

K

651 – 1350

R

1351 – 2000

> 2000

Total

I 6 0 0 0 0 6

II 24 53 0 0 0 77

IV 114 138 945 0 0 1197

V 55 147 627 753 0 1583

VI 54 190 801 644 1865 3553 Wa

terw

ay

cla

ss

Z 43 161 668 507 1491 2870

Total 296 688 3041 1904 3356 9285

Tab. 3 Statistics on unloaded voyages on Belgian waterways in 2007 [1000 km]

Ship type by loading capacity (ton)

< 400

S

401 – 650

K

651 – 1350

R

1351 – 2000

> 2000

Total

I 9 0 0 0 0 9

II 4 105 0 0 0 109

IV 300 214 524 0 0 1038

V 100 230 348 315 0 993

VI 27 314 445 268 565 1619 Wa

terw

ay

cla

ss

Z 10 268 371 211 452 1312

Total 449 1131 1688 794 1017 5081

2.3 Speed, power and fuel consumption

The next part of the analysis focuses on the speed of the inland vessels on the waterways mentioned in

the previous chapter. From figure 7, it is clear that the trial speed of these three classes of inland

vessels ranges between 16.0 and 20.5 km/h. It has to be noted that the source data of the figure spans

ships in which a new driving motor is installed between 1998 and 2003. It also only contains trial data,

thus in large and deep waters.

Fig. 4 The trial speed of inland waterway vessels (Van Gheluwe, 2009; original source: TNO)



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The reference speed data on more restricted waterways is obtained from measurements on the

Campine-barge “Prima” between Lommel and Antwerp in November 2009. This trajectory contains

waterways of class II, IV, VI and Z and is thus very apt as a reference case for the Campine-barge case.

Voyage data for the Péniche type is obtained from the skipper of the Dutch spits “Picaro” on several

Belgian waterways. As can be seen from figure 2, “Picaro” nicely represents the Spits-Péniche type of

ships. Missing data is based on resistance calculations. A detailed description of the resistance

calculation in shallow water will be presented in the next chapter.

Tables 4 and 5 represent the average forward speed for all types of ship in different waterway classes

and the average power consumption at these velocities.

Tab. 4 The average sailing speed per waterway class and type of ship (km/h)

Loaded Unloaded

S K R S K R

I 4.5 - - 6.0 - -

II 6.0 6.0 - 7.0 8.0 -

IV 7.0 9.0 6.0 9.0 11.0 11.0

V 10.0 11.0 10.0 12.0 14.0 14.0

VI 12.0 13.0 14.0 14.0 16.0 16.0

Z 14.0 16.0 18.0 16.0 18.0 20.0

Tab. 5 The average power per waterway class and type of ship (% of maximum continuous ratio)

Loaded Unloaded Power (%)

S K R S K R

I 13% - - 13% - -

II 22% 33% - 22% 33% -

IV 36% 60% 24% 36% 60% 24%

V 53% 83% 60% 53% 83% 60%

VI 100% 100% 100% 100% 100% 100%

Z 100% 100% 100% 100% 100% 100%

To estimate the fuel consumption, data provided by product guides of typical used engines from

Caterpillar and Volvo Penta, are used to determine the power needed and the average fuel

consumption as mentioned in the next two figures. (Georgakaki & Sorenson, 2004; Caterpillar, 2010)

Tab. 6 The average power per waterway class and type of ship (kW)

Loaded Unloaded Power (kW)

S K R S K R

I 26 - - 26 - -

II 47 97 - 47 97 -

IV 76 174 125 76 174 125

V 112 242 312 112 242 312

VI 210 290 520 210 290 520

Z 210 290 520 210 290 520

Tab. 7 The average fuel consumption per waterway class and type of ship (g/kWh)

Loaded Unloaded Fuel consumption

(g/kWh) S K R S K R

I 315 - - 315 - -

II 250 230 - 250 230 -

IV 230 220 225 230 220 225

V 220 218 210 220 218 210

VI 218 215 210 218 215 210

Z 215 215 210 215 215 210



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3. Resistance calculation in shallow water

To analyze the power needed in these restricted waterways, it is necessary to develop a method of

resistance analysis that takes into account the effects of shallow water and restricted width. Since this

study considers types of ships and not a specific ship an empirical method can be used.

In this case, the widely used and proven method as presented by Holtrop (1982, 1984) is used as a

base. The results are then further corrected for the effects of shallow and restricted water. A new

hybrid method is devised inspired by the methods of Schlichting (1934) and Landweber (Lewis, 1988).

3.1. Wave making resistance

First, an effective forward speed is determined from the actual speed to better predict resistance in

shallow water. Analogously to Schlichting, it is assumed that wave resistance depends on the wave

length of the transverse wave pattern of the ship. The relation between speed and wave length is

governed by the dispersion relation. A transversal wave system with wave length λ is generated by a

ship with velocity V∞ in deep water, and VI in shallow water of depth h:

π

λ

2

gV =∞ (1)

=

λ

π

π

λ hgVI

2tanh

2 (2)

This implies that the relation between velocities in deep and shallow water causing transversal wave

systems with equal wave length can be written as:

=

=

=

∞∞∞

2

2tanhtanh

2tanh

V

V

V

ghh

V

V SHALLOWkritI

λ

π

(3)

The critical velocity for shallow, but laterally unrestricted water with depth h can be found in the

previous equation and is defined as:

ghV

SHALLOWkrit = (4)

To also include limitations in width, the critical velocity for shallow water is replaced with the critical

velocity for a limited cross section. This critical velocity is dependent on water depth (h) and blockage

(m) and is given by (Briggs et al, 2009):

( ) 2

3

3

1sinsin2

−=

mArcghV

RESTRkrit (5)

The relation between velocity in deep water and shallow water can then be written as:

=

∞∞

2

tanhV

V

V

V RESTRkritRESTR (6)

Using these relations, the resistance curve for deep water can be corrected to better capture the wave

making resistance in shallow water.

3.2. Viscous resistance

Not only is a change in wave making resistance observed when sailing in restricted water. Due to the

limited cross section, the water flowing along the hull will speed up creating a return flow. This

phenomenon is important in determining the total resistance in restricted water and will need to be

accounted for adequately.

By using a one-dimensional approach, the relation between return flow and the ship’s forward speed

can be formulated using a third degree equation (Dand & Ferguson, 1973):

0112

1

2

1 2

3

2=+

∆+

−+−

∆+

V

VVmF

V

VVF nhnh

(7)



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in which:

V ship speed (m/s)

∆V velocity of the backflow (m/s)

g gravitational acceleration (m/s2)

0Ω= MA

m Blockage factor (-)

AM cross section wetted surface (≈BT) (m2)

B breadth of ship (m)

T draught of ship (m)

Ω0 wetted cross section of canal (m2)

WS width of the canal at the surface (m)

Wsg

VFnh

0Ω= depth Froude number (-)

For a certain value of forward velocity, this equation results in three different solutions for the return

flow, of which only one can be considered to be realistic. After determination of this solution, the

return flow and corresponding added viscous resistance can be calculated.

An example of the resulting resistance curve is given in Figure 5 for the Campine-Barge „Prima”:

Resistance curves for Campine barge "Prima" in deep and restricted waters

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16 18 20

Vessel speed [km/h]

Resis

tan

ce [

kN

]

Total resis tance for restricted water

Total resis tance for restricted water,

without return flow correction

Total resis tance for deep water

Fric tional resistance

Schematic representation of the cross section

-5

-4

-3

-2

-1

0

-16 -12 -8 -4 0 4 8 12 16

Width [m]

Dep

th [

m]

Mids hip section

Cross section wate rway

Freesurface

Fig. 5 The resistance curves of all steps in the calculation process.

The results of this method for the three characteristic vessels are summarized in Figure 6. One can

immediately notice the physical barrier that is created by the critical velocity of the ship in a restricted

waterway. In the 80% to 90% range of this critical value, a small increase in velocity results in a very

significant increase in resistance.



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Total resistance for Péniche-Spits "Picaro"

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16

Velocity (km/h)

Resis

tan

ce (

kN

)

in type section for waterway of class I

in type section for waterway of class II

in type section for waterway of class IV

in type section for waterway of class V

in type section for waterway of class VI

in type section for waterway of class Z

in unrestricted water

Total resistance for Campine-Barge "Prima"

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16 18 20

Velocity (km/h)

Resis

tan

ce (

kN

)

in type section for waterway of class II






Total Resistance for Rhine-Herne Canal ship "Adriaan"

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16 18 20

Velocity (km/h)

Resis

tan

ce (

kN

)






Fig. 6 Resistance curves for all types of ship in all canal classes.



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4. Emissions

The total fuel consumption per year for every ship types in certain waterway classes can be determined

as follows:

(Specific fuel consumption) * (power/ship) * (cargo carried * distance travelled / year) (8)

Velocity * loading capacity

This present the following fuel consumption for the inland waterway ships in question:

Tab. 8 Fuel consumption per ton carried.

Loaded Unloaded Total Ton fuel / year

S K R S K R S K R

I 29 11 40

II 129 360 57 160 186 520

IV 794 1064 4398 371 580 1500 1165 1644 5899

V 379 1281 4087 229 671 1991 608 1952 6078

VI 568 1653 6693 350 1024 3312 918 2677 10006

Z 387 1139 4272 213 759 2458 600 1898 6730

TOTAL 2287 5497 19451 1231 3194 9262 3518 8691 28713

Ton*km carried per year 296 688 3041 0 0 0 296 688 3040

Fuel consumed for every

ton km (g / ton km) 7.7 8.0 6.4 11.9 12.6 9.4

By multiplying the fuel consumption with the emission factors (weight fraction of emitted particles per

unit of fuel), the total emissions per year can be determined. The following emission factors are used

in the calculations:

CO2: 3173 g / kg

NOx 51.7 g / kg

PM10 2.1 g / kg

SO2 3.4 g / kg

CO2 and SO2 is only dependent on the fuel composition. Evidently, CO2 remains quasi constant while

the amount of SO2 depends on the fraction of sulfur in the fuel, which is mainly governed by

regulations.

The amount of NOx and PM10 on the other hand depend on the efficiency and setting of the engine.

The date of built of the engine and the maintenance prove to be determining factors.

Based on the estimation of fuel consumption in Table 8, the following emission values are obtained:

Tab. 9 Emission values per ton carried.

Fuel consumption and emissions (g/ton km) S K R Total

Fuel 12 13 9 10

CO2: 38 40 30 32

NOx 0.61 0.65 0.49 0.53

PM10 0.025 0.027 0.020 0.021

SO2 0.040 0.043 0.032 0.035



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5. Reducing resistance and fuel consumption, improving efficiency

5.1 Reducing frictional resistance

The frictional resistance is dependent on the wetted surface and the velocity, presented in non-

dimensional form by the Reynolds number, and the roughness of the surface. For a given vessel, the

roughness is the only parameter that can be influenced.

Regular maintenance of the ship’s hull is very important in keeping a low roughness. A regular

maintenance of the hull’s paint system will make sure the vessel moves smoothly through the water. A

trade-off has to be made since maintaining the underwater paint system creates downtime and

expensive docking sessions.

The use of non-sacrificial hard paints is making progress in the maritime navigation and will surely

become more commonly used in the years to come. Research at FORCE Technology (Westergaard,

2007) and Flanders Hydraulics / UGent (Vantorre et al, 2005) shows that improvements up to 10% are

possible if the coatings are maintained properly.

Another way of reducing resistance is the application of air lubrication. Pressurized air is injected into

the boundary layer along the ship’s hull which reduces frictional resistance, either through air bubbles

injected at the front or an air chamber underneath the hull (Hazeldine, et al., 2009).The generation of

this air lubrication sheet also requires power and will thus put an extra strain on the auxiliary systems

already on board.

It is proven that this technique works well at high speed, but even at moderate speeds as applied in

inland waterway navigation, a reduction of about 15% can be found (MARIN, 200-). This technique

on the other hand is easily influenced by hull roughness which will probably limit practical application

(Schilperoord, 2007).

To estimate the possible investment that can be made to reduce the frictional resistance, a theoretical

reduction by arbitrary means, will be applied from which the fuel reduction and emission reduction

will be determined. An increase in efficiency ca n be converted into either an increase in speed and

thus decrease of travel time if the power is kept constant or a decrease in fuel consumption if the speed

is kept constant. In order to quantify this reduction in tangible figures, it is assumed in Table 10 that

the velocity before and after the reduction is kept constant. The power requirement for the propulsion

of the vessel is thus reduced. In Table 11, the power is kept constant and the speed is thus increased.

Tab. 10 Reduction of fuel consumption and emission if frictional resistance is reduced with 10% and velocity is

unchanged.

S K R Total

FUEL (ton/year) 197 488 1852 2536

CO2 (ton/year) 624 1548 5875 8048

NOx (ton/year) 10.17 25.23 95.73 131.1

PM10 (ton/year) 0.413 1.025 3.888 5.326

SO2 (ton/year) 0.669 1.659 6.296 8.624

% 5.6% 5.6% 6.4% 6.2%



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Tab. 11 Reduction of fuel consumption and emission if frictional resistance is reduced with 10 % and power is

unchanged.

S K R Total

FUEL (ton/year) 38 97 360 496

CO2 (ton/year) 121 309 1143 1573

NOx (ton/year) 1.97 5.03 18.62 25.6

PM10 (ton/year) 0.080 0.204 0.757 1.041

SO2 (ton/year) 0.129 0.331 1.225 1.685

% 1.1% 1.1% 1.3% 1.2%

5.2 Reducing Wave Making Resistance

Wave making resistance becomes important at higher relative speeds. In restricted water, the wave

resistance increases sharply when the forward velocity approaches the critical speed. It is therefore not

advised to travel at such speeds in narrow canals and waterways. It is foremost in broader and deeper

waterways that a significant gain in economy can be made by reducing wave making resistance.

Literature suggests that an improvement between 5% and 20% can be made by improving hull design.

This is mostly show for new building projects; when reconverting existing ships, an improvement of

about 5% is envisaged (Schilperoord, 2007).

Wave resistance is created by the wave pattern generated at the free surface by the moving hull.

Reducing this wave pattern can be done by creating a beneficial interference behavior between the

different wave systems (bow-, stern-, front shoulder and aft shoulder waves) or by reducing for

example the bow wave with a sharper bow or bulbous bow.

Calculating and determining an optimal ship’s hull often requires model testing and advanced

calculation methods. A more straightforward method of reducing wave making resistance is

lengthening the hull.

A possible reduction of 10% is analyzed to determine the possible investment to produce this 10%

reduction.

Tab. 12 Reduction of fuel consumption and emission if wave resistance is reduced with 10% and velocity is unchanged.

S K R Total

FUEL (ton/year) 109 258 518 885

CO2 (ton/year) 347 817 1644 2808

NOx (ton/year) 5.65 13.32 26.78 45.7

PM10 (ton/year) 0.229 0.541 1.088 1.858

SO2 (ton/year) 0.371 0.876 1.761 3.009

% 3.1% 3.0% 1.8% 2.2%

5.3 Improving the efficiency of propulsion

Very little information is present about the propellers of the considered classes of inland ships, which

makes a good estimation of the propulsive efficiency unlikely. There are indications, however, that

this efficiency may be very low. In very shallow water, it may be as low as 20-40% while in maritime

navigation, values of 70% are reached (Georgakaki & Sorenson, 2004). This is probably wishful

thinking for inland ships due to the highly varying conditions in which they navigate, but some

improvement can surely be made.

Replacing the propeller with one more suited to the navigational conditions is such an improvement.

The propeller of the Campine-Barge “Prima” was changed from a three-blade propeller to a five-blade

propeller of the same diameter resulting in a speed gain of 1 km/h for the same fuel consumption.



13

When building an inland waterway vessel from scratch, a conventional propeller is hardly ever used

anymore. The ducted propeller governs the land of the new ships, existing older ships however can

benefit from the installation of a propeller duct since they are often still propelled by a conventional

propeller. Sources indicate that improvements ranging from 10% to 25% in thrust can be reached

(Hazeldine, et al., 2009; Zöllner, 2009)

Other measures may include such devices as:

Controllable pitch propellers

Contra rotating propellers or other devices that recuperate rotational energy

Replacing the engine by a much newer model will increase efficiency by about 15% to 20% (Lensink

& De Wilde, 2007). When this is not possible, older engines can be improved by installing for

example:

Catalytic convertor: the introduction of ammonium reduces the NOx emissions.

Soot particle filters; however, older engines often do not support the high back pressure

caused by the use of fully closed particle filters..

The use of diesel-electric propulsion systems can in some limited cases improve efficiency.

An indispensible tool is the fuel consumption gauge. In almost all new larger vessels, this gauge is

present and indicates to the driver the instantaneous fuel consumption. In this way, the driver can trade

off a velocity increase with a sharp increase in fuel consumption, especially at higher speed in

restricted water. After all, a small variation in velocity can result in high resistance if the waterway is

restricted (Heuser, 1994).

Again, one assumes an increase in efficiency of 10% in the propulsion system. This then results in the

following reduction of fuel and emissions.

Tab. 13 Reduction of fuel consumption and emission if propulsive efficiency is increase with 10% and velocity is

unchanged.

S K R Total

FUEL (ton/year) 352 869 2871 4092

CO2 (ton/year) 1116 2758 9111 12984

NOx (ton/year) 18 45 148 211.6

PM10 (ton/year) 0.7 1.8 6.0 8.594

SO2 (ton/year) 1.2 3.0 9.8 13.913

% 10.0% 10.0% 10.0% 10.0%

6. Conclusions

For inland navigation vessels with loading capacity between 250 and 1350 tons, consisting of the types

Spits/Péniche, Kempenaar/Campine Barge and Rhine-Herne Canal, an analysis is performed to

determine the use of all classes of waterways in Belgium. Using assumptions about forward velocity

and fuel consumptions, an estimate is made about the yearly fuel consumption and emissions.

Several possibilities for reduction of fuel consumption and emissions are investigated. Measures that

reduce the ship’s resistance can have a beneficial effect on fuel consumption and emission reduction

on the Belgian waterways when mainly the viscous or frictional resistance is reduced. A reduction of

wave making resistance is less beneficial due to the low forward speed in confined waters. Only in the

case of small inland ships travelling great distance on open water, a large impact in fuel consumption

and emissions can be detected if the wave making resistance is reduced.

Optimization of the propeller and/or the installation of a propeller nozzle may induce a large gain in

thrust and performance, especially on the older small inland ships, since they have originally been

designed for towed operation.



14

The results of this study can be used by the authorities to estimate the impact of measures taken to

improve the fuel consumption of smaller types of inland vessels in terms of yearly emission of

greenhouse gases.

Technical developments aside, it is very important that the skipper is aware of fuel consumption at all

time since it is a real-time indication of efficiency. It is therefore recommended to install a fuel

consumption indicator on existing small ships. A very important lesson to learn is that all investment

in a resistance reducing, or efficiency increasing measure is mainly turned into a greater forward speed

and a reduction in travel time and not into a reduction of fuel cost and emissions when no change is

made to the operational profile.

7. Acknowledgements

The research project “Verbeteren van het energierendement van bepaalde binnenschepen”

(“Improving the energy efficiency of specific inland waterway vessels”, 2009) was funded by the

Belgian Federal Public Service Mobility and Transport.

8. References

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