Effect of Engine Fastening Points’ Amount on the Vessel’s

Foundation towards Vibration Transmissibility Value in Traditional

Vessel Structures

Debby R. Lekatompessy

1,a

Department of Naval Architecture, Universitas Pattimura, Kampus Poka, Ambon, Indonesia

Keywords: Engine Foundation, Traditional Ship Structures, Transmissibility, Vibration.

Abstract: In the rubber damper designed in the previous study, vibration was reduced by 65% on engine no. 1 and 59% in

engine no. 2 with a considerable amplitude value of 0.0276 mm and 0.0282 mm, respectively. By using the

Barkan engine's allowable amplitude ranging from 0.02 mm - 0.03 mm, after the installation of a rubber damper,

the vibration can be reduced to safe limit. The research continues by analysing the machine foundation-stretching

system with the amount of fastening points of 2, 3, and 4. The increase in the number of fastening points causes

the amplitude to be reduced even further. The calculation results can be seen by reducing the value of the

transmission force to the foundation. By doing so, the amplitude value decreases as the engine’s load decreases

due to the system's work. The number of fastening points affects the value of the distribution of the bending

stress (s) and shear stress (ss). Increasing the fastening point reduces the value of the bending stress (s) and shear

stress (ss). The allowable bending stress (s) and shear stress (ss) used are 6.4 MPa and 0.45 MPa consecutively,

given by the National Design Specification. The calculation results show the value is below the allowable limit.

Based on the calculation results, the smallest amplitude value is obtained at the four-point fastening points.

Therefore, it is better if the amount of existing fastening points is increased. From these results, it can be seen

that the foundation is still within the safety limits.

1 INTRODUCTION

Ships with outboard engine type, vibrations

transmitted to the foundation beam without damping

exceeded Barkan permissible amplitude, i.e., 0.02

mm to 0.03 mm in the vertical direction (Srinivasulu,

1980). This condition indicates that the system

requires a damper that can reduce vibration to a safe

limit. Calculations must be made using Barkan

permissible amplitude limits. Also, the vibration

limits are permitted for structural damage, machinery

vibration, and human perception in graphical form for

operator safety (Hopcroft and Skinner, 2005).

Damping in this study uses rubber material with E

value at 2.3 x 109 N/m2 . The rubber dimensions are

determined through variations in prices of c and k

with thickness t = 0.2 cm to 3 cm (Lekatompessy et

al., 2013). Based on measurement at Point F around

the beam foundation, an effective damping rubber

dimension is obtained at 8 x 5 x 2 cm.

At this point, the most significant excitation force

(F0) and the smallest excitation frequency () are

obtained, with the most substantial amplitude value

(Lekatompessy, 2003).

In further research, the fishing factor is seen by

analysing the effect of the number of fishing spots on

the distribution of vibrations and loads on the wooden

ship's engine foundation (Ariana, 1998).

2 LITERATURE REVIEW

2.1 Engine Vibration

Imbalance in a rotating machine is a common source

of vibration excitation. The mass-spring system is

limited only to moving in a vertical direction and

stimulated by a rotating machine (Jensen and

Chenoweth, 1991). From Figure 1, an equation is

obtained as follows:

𝑚𝑐𝑘𝑥



𝑚𝑒𝜔





sin𝜔𝑡

(1)

By replacing F

with 𝑚𝑒𝜔

Lekatompessy, D.

Effect of Engine Fastening Points’ Amount on the Vessel’s Foundation towards Vibration Transmissibility Value in Traditional Vessel Structures.

DOI: 10.5220/0010855100003261

In Proceedings of the 4th International Conference on Marine Technology (senta 2019) - Transforming Maritime Technology for Fair and Sustainable Development in the Era of Industrial

Revolution 4.0, pages 111-116

ISBN: 978-989-758-557-9; ISSN: 2795-4579

 2022 by SCITEPRESS – Science and Technology Publications, Lda. All r ights reserved

111

Figure 1: Harmonic disruptive force obtained from an

imbalance of the rotating mass.

From Equation (1), the steady-state solution can

be replaced by:

𝑥

𝑚𝑒𝜔







𝑘𝑀𝜔









𝑐𝜔





(2)

tan𝜙

𝑐𝜔

𝑘

𝑀

𝜔



(3)

2.2 The Rotating Mass

In mechanical systems and structures, displacement

indicates stress and strain, which fail the system.

Resonance conditions must be avoided (Seto, 1992).

The amplitude can be calculated using the following

equation:

𝑥

𝐹



𝑘



1 



𝜔











2𝜉

𝜔







(4)

Excitation force is obtained using the following

equation:

𝐹



𝑘.𝑥





1



𝜔















2𝜉

𝜔







(5)

2.3 Comparison with Applicable

Standards

The effects of vibration can damage the machining

system. It can affect the health of the machine

operator too. Therefore, the machine's vibration level

must be limited so that safety and comfort for the

operator and the system can be maintained.

Table 1: Allowable amplitudes.

Source: Srinivasulu, 1980

3 RESEARCH METHODS

This research focuses on the vibration on the traditional

motorboat's foundation system with outboard engine

type, with two pieces of high-speed diesel motor (2200

rpm) as a driving force (Ghozali, 2007).

The questions of this research are to see whether

the system is in a safe condition? How much is the

vibration from the ship's engine that the channel

system can damp? How significant is the role of

rubber as a damper in the system? Whereas

economically, used car tires are the material of choice

because they are cheap and easy to obtain

(Lekatompessy et al., 2014).

The problem that arises is how to obtain a rubber

size to be effective as a vibration damper without

changing the size of the engine supporting channel.

Technically, the channel's size must be replaced

because one of the solutions to reduce the system is

that a large mass supports the system. This condition

does not benefit the fishermen and the ship's skipper

because it requires burdensome costs. This study aims

to determine the effect of the number of fastening

spots on the machine's transmissibility value to the

surrounding structures. The parameters used as a

limitation are the Barkan permissible amplitude and

the graph of the allowable limits for Structural

Damage Machinery Vibration and Human perception

(Inman D. J., 1996).

From Table 2, it can be seen that the installation

of rubber at point F is capable of reducing vibration

by 54% in engine 1 and 53% in engine 2.

Table 2: Vibration reduction in the beam foundation area

before and after damping

Before Afte

Diff %

ine 1 0,059 0,027 0,032 54%

Engine 2 0,060 0,028 0,032 53%

ePermissible am

litude

(

)

Low speed engine (500 rpm)

Hammer foundation

0.02-0.025

0.1-0.12

h s

eed en

ine

a) 3,000 rpm

 Vertical vibrations



Horizontal vibrations

0.002-0.003

0.004-0.005

b) 1,500 rpm

 Vertical vibrations



Horizontal vibrations

0.004-0.006

0.007-0.009

senta 2019 - The International Conference on Marine Technology (SENTA)

112

Figure 2: Research flow chart.

4 RESULTS AND DISCUSSION

4.1 Foundation Strength Calculation

for Engine 1

The foundation strength is calculated based on the

maximum bending moment M and the transverse

shear force V. The data needed for this calculation

are:

• Weight of engine and engine bed = 23.445 N

• Transmission Force (F

TR1

) = 1,610.7009 N

4.1.1 2-Points Fastening

Load Distribution of Engine 1 at the engine

foundation with 2-point fastening has seen in Figure

3. The maximum bending moment is calculated using

the following equation:

𝑀𝑃



.𝑎

(6)

Where,

: ¼ (engine and engine bed +

transmission force)

a : 1,350.5 mm

then,

M = ¼ (23.445+1,610.7009) . 1,350.5

= 551,728.7 N.mm

Figure 3: Load distribution at the foundation with 2-

points fastening

Reaction to support (R) can be calculated as

follows:

𝑅

8𝑀

2𝐿



8 ∗ 551,728.7

2 ∗ 3,175

695.09 N

(7)

The transverse shear force V is equal to the value

of R (V = R), i.e. V = 695.0912 N. To determine the

maximum bending stress, the equation is:

𝑠

𝑀

𝑍

(8)

Where,

= bh

/6 (9)

Noted that,

b = 220 mm

h = 225 mm

then,

𝑍

220 ∗ 225



1,856.250 mm



Therefore,

𝑠





551,728.7

1,856,250

0.297MPa

For the maximum shear stress (s

) of a rectangle:

𝑠





3𝑉

𝐴

(10)

Where,

A = (220)(225)

= 49,500 mm

Therefore, the shear stress can be determined as

follows:

= 0,021 MPa

The closest quality of wood is used to determine

the permitted bending stress (s) and shear stress (s

namely pine ponderosa No. 1, with s permission = 6.4

Effect of Engine Fastening Points’ Amount on the Vessel’s Foundation towards Vibration Transmissibility Value in Traditional Vessel

Structures

113

MPa and s

permission = 0.45 MPa, approved by

National Design Specification. From the calculation

results, it can be seen:

𝑠𝑠



0.2976.4



MPa



𝑠



𝑠

 

0.0210.45



MPa





From these results, it can be seen that the

foundation is still within the limits of permission in

accepting the load of working on it. Other calculation

results can be seen in Table 3.

4.1.2 3-Points Fastening

Load Distribution at the engine foundation with 3-

points fastening has seen in Figure 4.

Figure 4: Load distribution at the foundation with 3- points

fastening.

The calculation is done in the same way as 2-

points fastening, where the results can be seen in

Table 3.

4.1.3 4-Points Fastening

Load distribution at the engine foundation with 4-

points fastening has seen in Figure 5. The calculation

is done in the same way as above, where the results

can be seen in Table 3.

4.2 Foundation Strength Calculation

for Engine 2

The foundation strength is calculated based on the

maximum bending moment M and the transverse shear

force V. The data needed for this calculation are:

• Weight of engine and engine bed = 21.916 N

• Transmission Force (F

TR1

) = 1,638.0009 N

4.2.1 2-Points Fastening

The maximum bending moment is calculated using

equation (6), therefore,

M = 560,429.6 N.mm

Reaction to support (R) (Equation 7):

R = 706.053 N

Figure 5: Load distribution at the foundation with 4- points

fastening.

Figure 6: Load distribution at the foundation with 2- points

fastening

senta 2019 - The International Conference on Marine Technology (SENTA)

114

The transverse shear force V is equal to the value of

R (V = R), i.e., V = 706.053 N.

Equation (6) is used to determine the maximum

bending stress as follows:

Where,

Z = 1,856.250 mm

Therefore,

maks s = 0.3019 MPa

Equation (10) was used to determine the maximum

shear stress (ss) of a rectangle:

Where,

A = 49,500 mm

thus,

= 0.0214 MPa

From the calculation results, it can be seen:

𝑠𝑠



0.30196.4



MPa



𝑠



𝑠

 

0.02140.45



MPa





From these results, it can be seen that the

foundation is still within the limits of permission in

accepting the load of working on it. Other calculation

results can be seen in Table 3.

4.2.3 3-Points Fastening

Load distribution of engine 2 to the engine foundation

with 3-points fastening has seen in Figure 7. The

calculation is done in the same way as above, where

the results can be seen in Table 3.

4.2.4 4-Points Fastening

The distribution of loading at the engine foundation

with 4-points fastening has seen in Figure 8. The

calculation is done in the same way as above, where

the results can be seen in Table 3.

Figure 8: Load distribution at the foundation with 4- points

fastening

5 CONCLUSIONS

Based on the comparison, we can see that the shear

force's magnitude and the bending moment have

decreased. This change indicates that dissipation

occurs with the addition of the amount of fastening.

The results have shown the reduction of the

transmission force to the foundation. By itself, the

value of amplitude to the base decrease due to the

work of the system.

This study's results reinforce the results of

previous studies where the damping and stiffness

values were varied to obtain the smallest amplitude

value. The increase in stiffness through the number of

Figure 7: Load distribution at the foundation with 3- points

fastening

Table 3: Results of foundation strength calculations.

Description Unit

ine 1 En

ine 2

oint 3 point 4-

oint 2-

oint 3 point 4-

oint

m kg 23.446 23.446 23.446 21.916 21.916 21.916

N 1,610.71 1,610.71 1,610.71 1,638.00 1,638.00 1.633001

N 408.537 272.358 204.268 414.979 276.653 207.49

N 551728.7 367,319.10 275,364.30 560,429.60 373,619.70 230.2143

N 695,091 463.394 347.546 706.053 470.702 353.027

V 695,091 463.394 347.546 706.053 470.702 353.027

1,856,250 1,356,250 1,856,250 1,856,250 1,856,250 1,856,250

0.29723 0.19815 0.14861 0.30392 0.20128 0.0151

0.02106 0.01404 0.01053 0.0214 0.01426 0.0107

Effect of Engine Fastening Points’ Amount on the Vessel’s Foundation towards Vibration Transmissibility Value in Traditional Vessel

Structures

115

fixing points makes this research more optimal for

reducing amplitude. The number of fixing points

affects the value of the distribution of bending stress

(s) and shear stress (ss). The increasing of the

fastening point reduces the value of bending stress (s)

and shear stress (ss).

Based on the calculations' results with the two,

three, and four-point fastening models, the smallest

amplitude value is obtained at the four-point drafting.

Several other factors also affect increasing the value

of structural stiffness apart from those in this study.

The type of material and the dimensions of the

foundation also affect the amplitude value. Further

research can be done on this matter to support the

research results that have been done.

REFERENCES

Ariana, I.M. 1998. Getaran Permesinan Kapal: Handout

FTK, Surabaya: Institut Teknologi Sepuluh Nopember.

Ghozali, M. 2007. Analisa Getaran Pondasi Motor

Pengerak Kapal Ikan Tradisional Tipe Outboard

Engine, Surabaya: Institut Teknologi Sepuluh

Nopember.

Hedge, A. 2007. Human Vibration

http://ergo.human.cornell.edu.com.

Hopcroft, R., and Skinner, M. (2005). Human Vibration,

http://dspace.dsto.defence.gov.au/dspace/bitstrea

m/1947/4336/1/DSTO-TR-1756.pdf.

Inman, D. J. (1996). Engineering Vibration, International

Editions, Prentice Hall Inc., USA.

Inman, D. J. (1996). Engineering Vibration, International

Editions, Prentice Hall Inc., USA.

Lekatompessy, D.R. (2003) Tinjauan Pengaruh Getaran

Mesin Terpasang Terhadap Kekuatan Konstruksi

Pondasi Kapal Tradisional, Thesis, Institut Teknologi

Sepuluh Nopember, Surabaya.

Lekatompessy, D. R., Sulaiman, O. O., Manuhutu, F., de

Lima, E. J., and Manuputty, M. (2013). Rubber as an

Effective Vibration Absorber of Outboard Engine at

Small Traditional Fishing Boats from the Human

Health and Safety Point of View. Journal of

Engineering Computers & Applied Sciences 2 (2): 7–

12.

Seto, W. W. (1992). Getaran Mekanis (Machine Vibration).

Translate by Sebayang Darwin, Erlangga, Jakarta.

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