Analysis of the Effect of Addition of Bilge Keel, Bulbous Bow, Skeg

and Combination on Value of Ship Resistance and Seakeeping of Ship

using CFD Method

Ari Wibawa Budi Santosa, Berlian Arswendo Adietya, Eko Sasmito Hadi and Deddy Chrismianto

Naval Architecture Department, Diponegoro University, 50275 Semarang, Indonesia

Keywords: Resistance, Seakeeping, Bulbous Bow, Skeg, Bilga Keel.

Abstract: The hull added by the Bulbous Bow, Skeg, and Bilge Keel can improve the ship's ability to operate. Based on

several studies it is known that the best bulbous bow model is the V model, the best Skeg form is the Foil

model and the most optimal Bilge Keel form is the hollow triangle shape, where the most optimal variation

is to reduce the value of the resistance and ship seakeeping. To achieve these objectives, several stages are

carried out, namely making a model, then analyzing the model using CFD software. The results of this study

indicate that the best resistance value occurs in the ship model with Bilge keel with a value of 8.8 kN or a

decrease of 13.72% of the ship without the addition of components. Then for the value of the Motion obtained

Heaving value of 0.84774 m on the ship without the addition of components, for the best pitching value that

is on the ship with the addition of Bulbous bow, Skeg and Bilge keel with a value of 0.080775 radians and

for the best Rolling value is on the Ship with additions Bilge keel with a value of 0.0000082404 rad.

1 PREFACE

The development of the shipping world is growing.

This is related to the performance of the ship which is

getting better over time. In the design of the ship there

is a lot that must be considered including the

resistance that occurs and the

seakeeping of the ship.

The resistance and speed of flow in the propeller of

the ship will have a large influence on speed. In

addition, high resistance also affects the power

requirements to reach a certain speed. The greater the

resistance of the ship, the greater the main engine

power (main engine) needed to push the ship (Daud

et al., 2019).

Beside of the resistance, the thing to note is the

seakeeping. Seakeeping is the ability to defend itself as

a result of waves that occur. We often call it

Seakeeping. Seakeeping is one of the most important

components to find out if the ship has the feasibility

of making a cruise on the ocean waves. To get the

seakeeping value can be analyzed using Towing Tank

or computational or CFD methods. The vessels used

in this study are mono hull vessels with modified

component additions, namely bulbous bow, skeg and

bilge keel.

Variations in the geometric shape of the skeg

when using the bilgekeel model which has the

smallest total resistance value are Foils with a value

of 9.28 KN in the position of AP (stern) and model

without using bilgekeel which has the smallest total

resistance value ie Foils with a value of 9.31 KN in

the AP position (Stern). The Foils model has the

smallest resistance value because the laminar

structure of the foils model can accelerate the flow of

water and no flow is blocked when passing through

the structure of the foils (Rishwanda., 2018).

While the shape of the bilga keel used is a hollow

bilga with a triangular shape which has the smallest

resistance value which can reduce the total resistance

of the vessel by 20.626% at Fn 0.28 and 16.396% at

Fn 0.36 (Avian et al., 2018).

This study will focus on the comparison of the

values of resistance and Seakeping from each

variation with the CFD method. At present, CFD has

become a numerical device that is very effective in

analyzing fluid flow. ABS, as one of the classification

bureaus, is making efforts to implement CFD

technology to apply CFD technology to assess the

strength of modern commercial vessels and high-

speed naval vessels. Software used is Software

Analysis of seakeeping.

Santosa, A., Adietya, B., Hadi, E. and Chrismianto, D.

Analysis of the Effect of Addition of Bilge Keel, Bulbous Bow, Skeg and Combination on Value of Ship Resistance and Seakeeping of Ship using CFD Method.

DOI: 10.5220/0010056900880093

In Proceedings of the 7th International Seminar on Ocean and Coastal Engineering, Environmental and Natural Disaster Management (ISOCEEN 2019), pages 88-93

ISBN: 978-989-758-516-6

From the explanation above the problem can be

formulated in this study, namely the effect of adding

components to the value of resistance and sea keeping

and the comparison of the value of resistance and

seakeeping of each variation.

2 METHODS

In this study, the authors have primary data on the

main size of the KM Egon vessel:

LOA : 26.370 m

B : 5.500 m

T : 1,000 m

H : 2.622 m

V : 10 Knot

Wave Direction : 180 degree

For secondary data obtained from the literature

(journals, books, and data obtained from previous

studies).

The parameters of the study were focused on the

effect of adding components to the hull on barriers

and vessel seakeeping. The parameters used are as

follows:

1. Permanent Parameters

The author uses primary data of the main size of

the KM ship. Egon as a fixed parameter in this

study.

2. Variable Parameters

 Ship without Component Additions

 Ship with the addition of bulbous bow type V

 The vessel with the addition of a Bilge Keel

hollow triangular shape with a 50% LOA

Length

 Ship with the addition of Skeg in the form of

Foils

 Ship with the addition of Bulbous bow, bilge

keel, and skeg

The process of making a model using Modeler.

Calculation of resistance and seakeeping uses the

Computational Fluid Dynamics (CFD) method,

which is one branch of fluid mechanics that uses

numerical methods and algorithms to solve and

analyze problems related to fluid flow (Kim, 2011).

The Computational fluid dynamics method

consists of three main elements, namely:

 Pre Processor

 Solver Manager

 Post Processor

Computational fluid dynamic cannot completely

replace measurements experimentally, but the

amount and cost of experiments performed can be

reduced.

3 RESULTS AND DISCUSSION

3.1 Data Processing

This Design Modeling using Modeler.

Figure 1: Model of Ship Without Additional Components.

Figure 2: Model of Ship with Bulbous Bow Model V.

Figure 3: Model of Ship with Hollow Triangle Bilge Keel.

Figure 4: Model of Ship with Skeg Shape Foil.

Analysis of the Effect of Addition of Bilge Keel, Bulbous Bow, Skeg and Combination on Value of Ship Resistance and Seakeeping of Ship

using CFD Method

Figure 5: Model of ship with bulbous bow, Bilge keel, and

Skeg.

After the model is ready, then the resistance

values are tested and the motion is performed on the

CFD software.

3.2 Value of Resistance

To get the resistance value, the author uses CFD

software with the Hulltrop method, an efficiency of

85% and a speed of 10 knots. The test results of each

variation can be seen in the following figure

Figure 6: Ship Surface Image without Additional

Components.

Figure 7: Resistance and Ship Speed Chart without

Additional Components.

From testing on ships without additional

components, the value of the total resistance was 10.2

kN at a speed of 10 knots.

Figure 8: Ship Surface with Skeg.

Figure 9: Resistance and Ship Speed Graph with Skeg.

From testing on a ship with Skeg, the total

resistance value of 9.4 kN was obtained at a speed of

10 knots.

Figure 10: Surface Ship with Bulbous Bow.

Figure 11: Resistance and Ship SpeedGraph with Bulbous

Bow.

From testing on a ship with a bulbous bow, it was

found that the total resistance was 10.6 kN at a speed

of 10 knots.

ISOCEEN 2019 - The 7th International Seminar on Ocean and Coastal Engineering, Environmental and Natural Disaster Management

Figure 12: ShipSurface with Bilge Keel.

Figure 13: Resistance and Ship Speed Graph with Bilge

Keel.

From testing on a ship with a bulbous bow, it was

found that the total resistance was 8.8 kN at a speed

of 10 knots.

Figure 14: Ship Surface Combination.

Figure 15: Resistance and Ship Speed Graph Combination.

From chart above can be summarized in the

following diagram

Figure 16: Resistance Value Graph for each variation.

Based on the graph above, it can be concluded that

the most optimal resistance value of each

predetermined variation is on the ship model with the

addition of Bilge Keel with a value of 8.8 kN. When

compared with the resistance value of the ship

without adding components, the addition of bilge keel

components can reduce the value of the resistance by.

3.3 Value of Seakeeping

The seakeeping sought in this study is the natural

response of an object when hit by waves, including

Heaving, Pitching and Rolling.

The waves used are regular waves with a wave

frequency of 0.04 Hz, wave height of 1 m and the

direction of the wave is 180 degrees.

The results of the ship seakeeping from each

variation can be seen in the following Table and

Diagram:

Table 1: Heaving value for each variation.

Model Heaving Value (m)

Without 0.84774

Bulb 0.85998

Skeg 0.86012

Bilge 0.85881

Combination 0.86621

From Table 1 it is known that the smallest value

of Heaving occurs in the model without the addition

of components with a value of 0.84774 m. This can

happen because the Heaving seakeeping

displacement value greatly affects the value of the

Heaving.

Resistance Value

Column1

Analysis of the Effect of Addition of Bilge Keel, Bulbous Bow, Skeg and Combination on Value of Ship Resistance and Seakeeping of Ship

using CFD Method

Figure 17: Heaving Value Diagram.

From Figure 17 above, it can be seen the

difference in the value of heaving from each model

variation where the effect of adding displacement

actually adds to the heaving value of the ship

Table 2: Pitching value for each variation.

Model Pitching Value (radian)

Without 0.081658

Bulb 0.080820

Skeg 0.081457

Bilge 0.081250

Combination 0.080755

From Table 2, it can be seen that the lowest

pitching value is on the Ship with a combination of

the addition of Skeg, Bulbous Bow and Bilge keel

with a value of 0.080755 radians.

Figure 18: Pitching Value Diagram.

From Figure 18 it can be seen that the Pitching

value is influenced by the addition of components in

the longitudinal section, namely the bulbous bow

even though the addition of the keel and skeg bilge

also reduces the pitching value but is not significant.

Table 3: Rolling value for each variation.

Model Rolling Value (m)

Without 0.0000157195

Bulb 0.0000122404

Skeg 0.0000102404

Bilge 0.0000082404

Combination 0.0000092404

From Table 3, the lowest rolling value can be seen

on the Ship with Bilge Keel with a value of

0.0000082404 radians.

0,835

0,84

0,845

0,85

0,855

0,86

0,865

0,87

Heaving Value

Column1

0,0802

0,0804

0,0806

0,0808

0,081

0,0812

0,0814

0,0816

0,0818

Pitching Value

Series 1

ISOCEEN 2019 - The 7th International Seminar on Ocean and Coastal Engineering, Environmental and Natural Disaster Management

Figure 19: Rolling Value Diagram.

From Figure 19 it was affected by the addition of

components in the transverse direction such as Bilge

Keel and Skeg, but the addition of Bilge Keel was

more significant in reducing the Rolling value.

4 CONCLUSION

Based on the experiments that have been done, it can

be concluded as follows:

The value of total resistance is best for ships with

the addition of triangular and hollow bilge keel which

can reduce ship resistance by 13.72% with a total

resistance value of 8.8 kN.

For the value of sports, each boat has a significant

difference. The best value of Heaving is on a Ship

without Component Addition with a value of 0.84774

m, for Pitching the best value is found on a Ship with

a combination of adding a bulbous bow, skeg and keel

bilge with a value of 0.080775 radians and in Rolling

the best value is on the Ship Bilge Keel with a value

of 0.0000082404 radians.

REFERENCES

Sihombing, Daud Martim; Amiruddin, Wilma; Iqbal,

Muhammad. “Analisa Performa Penambahan Hull

Vane Terhadap Hambatan dan Seakeeping Kapal

Perintis 750 DWT dengan Variasi Foil Menggunakan

Metode CFD,” Jurnal Teknik Perkapalan, [S.l.], v. 7, n.

2, apr. 2019. ISSN 2338-0322.

Samudera, Rishwanda Alun. Analisa Pengaruh Bentuk

Geometri Skeg Terhadap Stabilitas dan Hambatan pada

Kapal Ikan KM. Mino Tambah Barokah. Jurnal Teknik

Perkapalan, [S.l.], v. 6, n. 4, oct. 2018. ISSN 2338-

0322.

Utami, Avian Putri; MANIK, Parlindungan; Budiarto,

Untung. Analisa Pengaruh Geometri Lunas Bilga

Berongga Terhadap Hambatan dan Wake Pada Kapal

Ikan Tradisional (Studi Kasus KM. Putra Samudra-02)

Menggunakan Metode Computational Fluid Dynamic

(CFD). Jurnal Teknik Perkapalan, [S.l.], v. 6, n. 4, oct.

2018. ISSN 2338-0322.

S. Kim, “CFD as a Seakeeping tool for ship design,” Int. J.

Nav. Archit. Ocean Eng., vol. 3, no. 1, pp. 65–71, 2011.

0,835

0,84

0,845

0,85

0,855

0,86

0,865

0,87

Rolling Value

Series 1

Analysis of the Effect of Addition of Bilge Keel, Bulbous Bow, Skeg and Combination on Value of Ship Resistance and Seakeeping of Ship

using CFD Method