TANJUNG PIAI COASTLINE
SURAYA BINTI AB RAZAK
A project report submitted in partial fulfilment of the
requirements for the award of the degree of
Master of Engineering (Civil – Hydraulics and Hydrology)
Faculty of Civil Engineering
Universiti Teknologi Malaysia
MAY 2008
iii
To the people I love
and
to the people who love knowledge
iv
ACKNOWLEDGEMENT
I would like to express my gratitude to all those who gave me the possibility
to complete this project report. Special thank you to my supervisor, Professor Dr.
Ahmad Khairi Abdul Wahab for his detailed and constructive comments, and for his
important support throughout this work. I want to thank En. Roslee Ibrahim and En.
Abd Rahman Mohamad Yusof from Jabatan Laut Semenanjung Malaysia (Wilayah
Selatan) and Pn. Rubiatun Adawiah Ali from Jabatan Pengairan dan Saliran, Pontian
for giving me the information and permission to use departmental data, and to all the
staff for their kindness and warmth.
I would also like to thank Assoc. Prof. Dr. Omar Yaakob and Dr. Mohamad
Pauzi Abdul Ghani from Department of Marine Technology, Faculty of Mechanical
for giving me some ideas and lending of material. Also to Dr. Zulhilmi Ismail who
involved in the process.
I am grateful to my mother for being supportive despite my determination to
continue the degree and support me all this while, financially and mentally, during
hard times. Not to forget my father and family members for their unconditional love
and understanding.
To all my friends, thank you for being helpful and supportive in any way.
v
ABSTRACT
Tanjung Piai coastline has been facing critical erosion for years but recently
the erosion rate is escalating. Numerical analysis of ship induced waves was carried
out to determine the contribution of shipping traffic from Pelabuhan Tanjung Pelepas
to the stability of Tanjung Piai coastline. The analysis includes the generation of
waves from ships, propagation, transformation from deep water to shallow water and
energy formation. Waves generated by ships decrease gradually when it propagate
away from the sailing line and then increase near to the shore due to shoaling and
damping factor. Bigger waves break near to the shore but smaller waves reach the
shore without breaking. Maximum wave height generated by ships at the shoreline is
0.51 meter and the wave period is 3.23 seconds. Wave heights generated by wind
were recorded to be between 1.2 and 1.7 meters with periods ranging from 4 to 8
seconds. Energy is related exponentially to wave height and bigger waves form
higher energy to the beach.
Based on wave energy to the shore, the analyses
conducted showed that ship induced waves does not contribute to the erosion at
Tanjung Piai coastline because of the small energy formation compare to wind
induced waves.
vi
ABSTRAK
Pantai Tanjung Piai berhadapan dengan masalah hakisan yang kritikal sejak
bertahun yang lalu tetapi kadar hakisan semakin bertambah sejak kebelakangan ini.
Analisis berangka terhadap ombak yang dihasilkan oleh kapal telah dijalankan untuk
menentukan sumbangan lalulintas kapal daripada Pelabuhan Tanjung Pelepas kepada
kestabilan pantai Tanjung Piai.
Analisis yang telah dijalankan melibatkan
penghasilan ombak daripada kapal, penyebaran, perubahan bentuk daripada air
dalam kepada air cetek dan penghasilan tenaga. Ombak yang dihasilkan oleh kapal
merosot sedikit demi sedikit apabila semakin menjauhi laluan kapal dan kemudian
bertambah apabila berhampiran pantai disebabkan oleh faktor pencetekan dan
redaman. Ombak besar pecah berhampiran pantai tetapi ombak kecil sampai ke
pantai tanpa pecah. Ketinggian maksimum ombak yang sampai ke pantai ialah 0.51
meter dan tempohnya ialah 3.23 saat. Ketinggian ombak yang dihasilkan oleh angin
yang direkodkan adalah di antara 1.2 dan 1.7 meter dengan tempoh 4 hingga 7 saat.
Tenaga berhubung secara exponen terhadap ketinggian ombak dan ombak yang lebih
besar menghasilkan kuasa yang tinggi kepada pantai. Berpandukan tenaga ombak
terhadap pantai, analisis yang dijalankan menunjukkan bahawa ombak yang
dihasilkan oleh kapal tidak menyumbang kepada hakisan di Tanjung Piai kerana
penghasilan tenaga yang kecil berbanding tenaga yang dihasilkan oleh ombak janaan
angin.
vii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
x
LIST OF FIGURES
xi
LIST OF ABBREVIATIONS
xiii
LIST OF SYMBOLS
xiv
INTRODUCTION
1
1.1.
Tanjung Piai
1
1.2.
Pelabuhan Tanjung Pelepas
3
1.3.
Objective
5
1.4.
Scope of Work
6
LITERATURE REVIEW
7
2.1
Wave Propagation
7
2.2
Wave Transformation
8
2.3
Refraction
9
2.4
Breaking
10
2.5
Ship Wave Theory
10
viii
3
4
2.6
Navigation Channel
17
2.7
Erosion
21
2.8
Tidal Effect
22
METHODOLOGY
25
3.1
Data Collection
25
3.2
Calculations
27
3.2.1 Wave Generation
27
3.2.2
Wave Propagation and Transformation
29
3.2.3
Wave Energy
32
DATA ANALYSIS
33
4.1
Navigation Channel
33
4.2
Profile of Vessel
34
4.3
Vessel Fleet
36
4.4
Shoreline Change
41
4.5
Existing Coastal Protection
42
4.6
Sample of Calculations
51
4.6.1 Speed of Vessel
51
4.6.2
51
4.7
5
Depth Froude Number
4.6.3 Wave Propagation Direction
51
4.6.4 Wave Period
52
4.6.5 Celerity
52
4.6.6
Wave Length
52
4.6.7
Wave Height
53
4.6.8 Beach Slope
53
4.6.9
54
Wave Transformation
4.6.10 Breaker Height
55
4.6.11 Maximum Wave Height
55
4.6.12 Wave Energy
56
Results
56
CONCLUSIONS AND RECOMMENDATIONS
66
5.1
66
Conclusions
ix
5.2
REFERENCES
Recommendations
67
69
x
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Classification of Coastal Erosion
21
4.1
Profile of Vessels
34
4.2
Total Vessel for Each Month in 2001
36
4.3
Total Vessel for Each Month in 2002
37
4.4
Total Vessel for Each Month in 2003
37
4.5
Total Vessel for Each Month in 2004
38
4.6
Total Vessel for Each Month in 2005
38
4.7
Total Vessel for Each Month in 2006
39
4.8
Total Vessel for Each Month in 2007
39
4.9
Total Vessel for 2001 to 2007
40
4.10
Summary of Data and Result of Study by JPS, Malaysia
42
4.11
Erosion Control Projects along Taman Negara Tanjung Piai 42
4.12
Bed Level Reading Behind Geotubes
48
4.13
Properties of Deep Water Ship Wave
57
4.14
Wave Heights Generated by Ship
57
4.15
Wave Frequency, Minimum, Average and Maximum Value 60
4.16
Wave Period, Length and Celerity at Certain Depth
4.17
Beach Slope, Breaker Depth, Breaker Height
and Breaking Type
61
62
xi
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Geotubes Installed at Tanjung Piai
2
1.2
Satellite Image of Pelabuhan Tanjung Pelepas
4
1.3
Vessel calls for 2003 and 2004
5
2.1
Schematic of Water Particle Trajectories
8
2.2
Idealised Plots of Waves Rays for Headlands and Bays
9
2.3
Wave Crest Pattern Generated at a Vessel Bow Moving
Over Deep Water
2.4
12
Cross Section of Pelabuhan Tanjung Pelepas Navigation
Channel
18
2.5
Ship Wave and Flow Pattern in a Canal
19
3.1
Flow Chart of Study Process
26
4.1
Vessel Fleet from 2001 to 2007
40
4.2
Erosion Rate
41
4.3
Wave Height and Direction (at 180ο)
43
4.4
Wave Height and Direction (at 120ο)
44
4.5
Wave Height and Direction (at 150ο)
45
4.6
Alignment of Geotubes
46
4.7
Location of Stick Gauge
47
4.8
Bed Level Reading Behind Geotubes
48
4.9
Condition Behind Geotubes on July 2004
49
4.10
Condition Behind Geotubes on November 2004
49
4.11
Condition Behind Geotubes on April 2005
50
4.12
Stick Gauge
50
4.13
Wave Height Generated by Ships
59
xii
4.14
Correlation between Wave Height, Beam, Length
and Draft of Vessel
59
4.15
Wave Frequency, Minimum, Average and Maximum Value 60
4.16
Bathymetry Map
63
4.17
Breaker Depth at Certain Beach Slope
64
4.18
Waves Transformation
65
4.19
Energy from Waves
65
xiii
LIST OF ABBREVIATIONS
COEI
-
Coastal and Offshore Engineering Institute
DANCED
-
Danish Cooperation on Environmental Development
DWT
-
deadweight tons
JPS
-
Jabatan Pengairan dan Saliran
LAT
-
Lowest Astronomical Tide
MSL
-
Mean Sea Level
PTP
-
Pelabuhan Tanjung Pelepas
SWPE
-
Ship Wave Pattern Evaluations
TEUs
-
Twenty foot Equivalent Units
ULCC
-
Ultra Large Crude Carrier
xiv
LIST OF SYMBOLS
B
-
beam
C
-
celerity
CB
-
block coefficient
cm
-
centimeter
D
-
draught
d
-
depth
db
-
breaking depth
Frd
-
depth Froude Number
Frl
-
length Froude Number
ft
-
foot
g
-
gravity acceleration
H
-
wave height
Hb
-
breaking height
Ho
-
deep water wave height
K dl
-
relative damping coefficient
K rl
-
relative refraction coefficient
K sl
-
relative shoaling coefficient
kJ/m
-
kilojoules per meter
L
-
length/wave length
Lo
-
deep water wave length
LOA
-
overall length
m
-
meter
m/s
-
meter per second
m/s2
-
meter per square seconds
xv
m/yr
-
meter per year
n
-
damping coefficient
s
-
second
T
-
wave period
V
-
speed of vessel
y
-
distance from sailing line
α
-
cups line angle
β
-
incident wave angle
γ
-
coefficient due to vessel size effect
ρ
-
water density
ζ
-
surface water elevation
ξb
-
surf similarity parameter
∇
-
volume of displacement
θ
-
propagation of direction
%
-
percent
ο
-
degree
CHAPTER 1
INTRODUCTION
1.1
Tanjung Piai
Tanjung Piai is the southern-most tip of mainland asia located in Pontian,
Johor, Malaysia. Tanjung Piai is unique for its mudflats coast and mangroves forest
which consist of many flora and fauna. Tanjung Piai has attained Ramsar status with
two other sites namely Pulau Kukup and Sungai Pulai in 2003 (Mustapha, 2003).
Tanjung Piai Ramsar Site is part of the larger southwest Johor wetlands.
The
southwest Johor wetland safeguard enormous biological diversity while providing
important benefits and services of national interest and supports the livelihood of
local communities.
Tanjung Piai is suffering from coastal erosion for many years and the area has
been identified as one of the critical area for coastal erosion under National Coastal
Erosion Study (Economic Planning Unit, 1985).
However, in recent years the
erosion has escalated significantly. Mangrove trees are being uprooted hence
exposing the shoreline.
It is predicted that this will contribute to the loss of
ecological integrity and characteristics in this Ramsar Site.
2
The coast is facing critical beach erosion since 1992 and the erosion rate has
been reported between 2.5 meter per year and 4.0 meter per year by Ministry of
Science, Technology and the Environment. Geotubes has been installed at Tanjung
Piai by Jabatan Pengairan dan Saliran (JPS), Malaysia in 2004 to mitigate the erosion
problem.
The geotubes seems to be ineffective in short term because the
sedimentation rate is slow (Wong, 2006).
The geotubes reduce wave energy effectively except during high tide. The
height of geotubes unable to reduce most of the wave energy and thus, the wave
height behind the geotubes are almost the same as the incident wave height.
Figure 1.1: Geotubes installed at Tanjung Piai (Source: JPS, 2005)
It is believed that the erosion accelerated during the busy ship traffic from
Pelabuhan Tanjung Pelepas (PTP) which operates since October 1999. Repetitive
waves actions on the same spot from the ships worsen the already vulnerable beach.
Not long after the Ramsar acceptance, international experts were promptly offered by
the Bureau of Environment, Science and Technology to study and recommend
remedial action to Tanjung Piai, in cooperation with the state of Johor.
3
Perbadanan Taman Negara, Johor (2007) stated that the study by Danish
Cooperation on Environmental Development (DANCED) showed that the erosion
from the west of Tanjung Piai results in sedimentation built up to the west of
Tanjung Piai. An approximate of 70 hectares of mangroves forest has diminished
due to erosion over two decades ago. Erosion currently has reached JPS bund
protecting the agricultural hinterland. The occurrence could be because of several
factor such as:
i)
Wave and flow change from nearby reclamation activities
ii)
Oil spill incident in Pontian – Selat Melaka water in 1997
iii)
Forefront mangroves died because of water pollution
iv)
Growth of ship traffic in Selat Melaka and Selat Tebrau water
v)
Dredging activities
vi)
Wind wave
Tanjung Piai might disappear from the map and loss the status as southernmost tip of mainland asia if the erosion . Listing Tanjung Piai as a Ramsar Sites is
one of the legal action to preserve the coastline area. Several other attempts such as
installing seawall and mangroves planting have been implemented but the outcomes
do not show expected results.
1.2
Pelabuhan Tanjung Pelepas
Pelabuhan Tanjung Pelepas (PTP) has been operating since October 1999
situated at the mouth of Sungai Pulai. Currently, PTP has the capacity to handle up
to 6 million TEUs per annum.
Phase Two of the port involves dredging and
reclamation of Bunker Island to upgrade the port bunkering facilities, and
construction of additional eight berths measuring a total of 208 km. The first two
berths of Phase II are now in operations and remaining berths will be constructed in
4
line with demand. The dredging project will widen the channel approach from 250
m to 400 m to enable two-way access for vessel traffic entering or leaving the port’s
harbour.
Meanwhile, widening and deepening the shipping access channel are to
receive the Super Post Panamax container vessels in the future. Also, the draught
will be deepened from 14 to 17 meters, allowing the port to accommodate the latest
vessels which have an average capacity of 6,000 to 8,000 TEUs without any
tidewater restrictions. The Port of Tanjung Pelepas is becoming a very busy port and
attracts the world’s largest liners, Maersk Line and Evergreen Marine Corporation
(ASEAN Ports Association, 2003).
Pelabuhan
Tanjung
Pelepas
Second Link
Tuas
Pulau
Kukup
Tanjung Piai
Figure 1.2: Satellite Image of Pelabuhan Tanjung Pelepas (Source: Google Map)
Figure 2 shows the satellite image of Pelabuhan Tanjung Pelepas, situated at
the mouth of Sungai Pulai. Ships navigate through Selat Melaka and Selat Tebrau
from one port to another.
5
In 2004, PTP set a new throughput handling record, with 4,020,421 TEUs
handled to maintain its position as Malaysia’s number one container terminal. The
throughout figure represented a 15.2% increase over last year’s 3,487,320 TEUs.
Local cargo handled, which represents 4.17% of total cargo handled, increased by
12%, from 150,000 TEUs in 2003 to 168,000 TEUs in 2004. Vessel calls shown a
rise of 1.4% (Figure 1.3), with 3,193 vessels calling at the port in 2004 compared to
3,148 vessels in 2003 (PTP Portfolio, 2005).
Vessel Calls
3200
Total Vessel
3175
3150
3125
3100
2003
2004
Figure 1.3: Vessel calls for 2003 and 2004
1.3
Objective
The objective of this project is to investigate the generation and propagation
of ship waves onto the coast of Tanjung Piai and their contribution to the stability of
the coastline.
6
1.4
Scope of work
This project will focus on wave properties generated by ships plying to and
from PTP within the area of the southern part of Selat Tebrau, between Tanjung Piai
and Tuas, Singapore.
CHAPTER 2
LITERATURE REVIEW
2.1
Wave Propagation
Waves can be classified according to a parameter referred to as the relative
depth, defined as the ratio of water depth d to wave length L. When this ratio is less
than approximately 1/20, waves can be classified as long waves or shallow-water
waves. Astronomical tides represent one important example of long waves. Long
waves are not limited to what is normally considered shallow water because the
relative depth is a function of wavelength. Waves are classified as short waves, also
referred to as deepwater waves, when the relative depth is greater than approximately
1/2. The geometry of short waves implies wave steepness great enough to cause
them to break. The class of waves between short (deep) and long (shallow) are
referred to as intermediate waves (USACE, 2003).
8
Figure 2.1: Schematic of water particle trajectories (Source: Ippen 1966)
Figure 2.1 shows the schematic of water particle trajectories for long, short
and intermediate waves as a function of depth. The horizontal velocity of a long
wave is maintained throughout the water column, from the surface to the bottom. In
the case of short waves, the strength of the horizontal and vertical component
decreases with depth to the point that waves do not induce bottom currents. Bottom
sediments can be eroded and transported by tidal and other long wave currents (Ippen
1966).
2.2
Wave Transformation
Wave transformation describes what happens to waves as they travel from
deep water into shallow water. Wave transformation is concerned with the changes
in wave height, wave length, wave celerity and direction. Wave period remain
constant throughout the process. Wave transformation, refraction and breaking are
best described by Kamphuis (2000) and his explanation is easy to understand.
9
2.3
Refraction
When waves approach the shore at an angle, wave refraction takes place in
addition to wave shoaling.
During refraction, the wave crests bend to align
themselves with the bottom contours and the wave direction becomes more
perpendicular to the shore. Waves will be higher at headland because of wave rays
convergence and lower in the bays because of divergence of wave rays.
Figure 2.2: Idealised plots of waves rays for headlands and bays (Source: Vincent
and Briggs 1989)
Figure 2.2 provides idealized plots of wave rays for several typical types of
bathymetry. Simple parallel contours tend to reduce the energy of waves inshore if
they approach at an angle. Shoals tend to focus rays onto the shoals and spread
energy out to either side. Canyons tend to focus energy to either side and reduce
energy over the head of the canyon. The amount of reduction or amplification will
depend not only on bathymetry, but on the initial angle of approach and period of the
waves. For natural sea states that have energy spread over a range of frequencies and
directions, reduction and amplification are also dependent upon the directional
spread of energy (Vincent and Briggs 1989).
10
2.4
Breaking
Wave shoaling causes wave height to increase to infinity in very shallow
water. There is a physical limit to the steepness of the waves. Waves breaks when
this physical limit exceeded. Wave shoaling, refraction and diffraction transform the
waves from deep water to the point where they break and then the wave height
begins to decrease markedly because of energy dissipation.
The breaking wave may have several shapes as it break. The breaker type is
the function of the beach slope and the wave steepness called the surf similarity
parameter and written as follows:
ξb =
tan β
H b / Lo
(2.1)
The types are spilling, plunging, collapsing and surging. According to Battjes
(1974), spilling breakers occurs when ξ b < 0.4 on flat beach, steep waves or both.
Plunging breakers occur on steeper beaches and/or for flatter waves when 0.4 < ξ b <
2.0. Collapsing breakers occur on steep beaches when ξ b > 2.0.
2.5
Ship Wave Theory
A moving ship causes a tensioning of the water surface in front of the bow,
the size of which in the direction of movement can amount to several times the
length of the ship (Arbeitsausschuss, 2004). Local build-up occurs directly in front
of the ship’s bow. The previously undisturbed cross section of the watercourse is
11
reduced by the cross-section of the ship. The flow around the ship must now take
place within a reduced flow cross-section. This causes an acceleration of the flow.
The entire depression alongside the ship has the character of a long wave and
is designated as a primary wave. Its wave length is equal to the length of the ship. In
canals, the depression stretches across the full width of the canal.
In wider
navigation channels, the depression decrease with increasing distance from the ship.
Ship wave or waves generated by ship have their distinction characteristics in
comparison with wave generated by wind. According to Allen and Yuhai (2003),
ship generated wave is of limited duration and its characteristics, such as propagation
directions, wave heights, and period vary with navigation orientation as well as the
distance from the ship navigation path. Ship waves are mainly short waves, less than
2.5 s periods. Multiple ship waves can reach as high as 1.5 m from the mean water
level.
As a vessel travels across the water surface, a variable pressure distribution
develops along the vessel hull. The pressure rises at the bow and stern and drops
along the midsection. These pressure gradients, in turn, generate a set of waves that
propagate out from the vessel bow and another generally lower set of waves that
propagate out from the vessel stern. The heights of the resulting waves depend on
the vessel speed, the bow and stern geometry, and the amount of clearance between
the vessel hull and channel bottom and sides. The period and direction of the
resulting waves depend only on the vessel speed and the water depth (CEM, 2003).
The pattern of wave crests generated at the bow of a vessel that is moving at a
constant speed over deep water is depicted in Figure 2.3. There are symmetrical sets
of diverging waves that move obliquely out from the sailing line and a set of
transverse waves that propagate along the sailing line. The transverse and diverging
waves meet along the cusp locus lines that form an angle of 19ο28' with the sailing
12
line. The largest wave heights are found where the transverse and diverging waves
meet. If the speed of the vessel is increased, this wave crest pattern retains the same
geometric form, but expands in size as the individual wave lengths and periods
increase.
Figure 2.3: Wave crest pattern generated at a vessel bow moving over deep
Water (Source: USACE, 2003)
At low speeds, there are several transverse waves along the hull but as speed
increases their number decreases as the waves become longer. At a length Froude
number of 0.3, the transverse waves are half as long as the vessel, meaning there is a
wave crest amidships. The crests of waves generated at the bow coincide with stern
wave crests, creating relatively high waves.
At a length Froude number of 0.4 the wavelength of the transverse waves
equals the length of the vessel, bow and stern wakes are reinforcing. This is also
known as ‘hull speed’ and for many conventional commercial vessels it is usually at
the top speed.
13
At a length Froude number of 0.6 the transverse waves are longer than the
hull length so pronounced changes in trim occur as the bow is on the crest of a wave
and the stern sinks into the trough. These longer waves would naturally travel faster
than the vessel and their generation is reduced, with the diverging waves becoming
more prominent.
At a length Froude number of 0.8 the diverging waves become very steep and
are probably breaking. A range of different wavelengths are generated, with each
wave travelling at a speed proportional to its length. This is known as dispersion,
which means the longer, faster waves leave the slower ones behind and curve
outwards from the sailing line. At a length Froude number of 1.0 the transverse
waves have almost died out but wave resistance is pretty much at its maximum
because of the large diverging waves (USACE, 2006).
The magnitude of the waves generated by a vessel depends on different
factors, particularly:
i.
Speed of vessel
ii.
Size of vessel
iii.
Passenger/cargo loading,
iv.
Shape of vessel hull,
v.
Distance from shore, and
vi.
Water depth
The characteristics of the wave group observed at the shoreline depend on a
large number of variables related to the moving vessel including position, heading,
and distance from shore, speed, hull geometry, trim and displacement, as well as the
properties of the ambient water body including depth contours, presence of currents,
or wind waves. The speed at which the design ship will be operated in the proposed
channel should be selected carefully. The engine setting is changed from sea speed
to manoeuvring speed when a ship approaches a harbour area. This usually limits the
14
maximum engine revolutions per minute (rpm) to less than the service speed
available in the open ocean.
Operational considerations also limit ship speeds
because of the need to reduce ship squat, increased ship resistance, and vessel wake
and wave effects on waterways (USACE, 2003).
Ship speeds are also governed by ship control needs where wind, currents,
and waves would tend to reduce the control margins. There is no doubt that there is
also some economic incentive to keep vessel speeds at the highest prudent level,
especially for projects with long transit distances or where tidal advantage is being
exploited. An important consideration is the minimum ship speed necessary to
maintain adequate ship steerage; this is normally four or more knots above the water
current. Transit speeds from 5 knots to 10 knots are the most common ship speed in
typical harbour channels as observed on a number of projects (USACE, 2003).
High speed craft generated waves generally comprise of long and short period
waves. The height of the long period waves increases when the depth of water
decreases and at the same time the wavelength decreases resulting in the increase of
wave steepness and this may lead to the breaking of the wave. The form and nature
of the breaking of a wave will vary with the slope of the coast and seabed. The level
of water will influence the position of the break point and the break point will move
closer to the coastline at high water. As longer waves are faster they reach the coast
earlier. Short-period waves subside faster than long-period waves and hence longer
waves are more observed at greater distance from the vessel track (Sorensen, 1973).
A part of ship waves usually becomes longer when the ship’s speed increases
(Somere, 2005). Kelvin wave pattern is the best-known feature of the flow behind a
ship. The angle of the divergent wave in a constant water depth does not depend on
the distance from the ship route, but on the ratio of the water depth and the speed at
super critical conditions (Hong and Doi, 2006). Hong and Doi also found that a
decrease in sectional area (d/L) increase the wave height but the slope of the shore
does not effect wave run-up.
15
Bernard et al. (2002) found that in near-bank, shallow water (d<0.5 m)
locations, sediment suspension was closely correlated with the primary boat-wake
waves (Hmax<0.21 m), indicating that maximum near-bottom orbital velocities were
sufficient to erode the fine grained (mud-silt) bottom materials.
In deep water, there are two sets of oblique diverging waves and a single set
of transverse waves, which move in the direction of the disturbance. The envelope
that contains the waves is described by a triangle with a half angle α of 19.3. This
pattern generally agrees with observations in deep water, but some discrepancies do
arise since the theory assumes that the pressure disturbance is concentrated at point
while, in reality, boats have finite length. As a boat moves into shallower water, the
waves begin to be influenced by the depth. While the transition is gradual and,
therefore, no sharp boundary between deep and shallow water exists, it is generally
accepted that the water is deep when d/L > 0.5. This boundary can also be expressed
in terms of the ‘depth-based’ Froude number,
Frd =
Vb
gd
(2.2)
of the boat, where Vb is the boat’s speed. For values of Frd greater than about 0.6 to
0.7, the waves will feel the presence of the bottom. Once this begins to happen, the
half angle of the envelope containing the waves begins to increase, up to a value of
90° when Frd = 1. Further increases in Frd result in decreases in α.
For vessels travelling at sub-critical Froude depth numbers, it can easily be
shown that the transverse waves decay at a much higher rate with lateral distance
than divergent waves (Sorensen, 1973).
16
The length of a vessel also plays a role in determining how large the
generated wakes are. This leads to the definition of a second Froude number, the
length Froude number
Frl =
Vb
gL
(2.3)
where L is the boat length. Studies have shown that when Frl ~ 0.5, wave heights are
once again maximized. Combining these two concepts, it is seen that a worst-case
scenario exists where the boat speed, length, and water depth are such that both
Froude number criterion are satisfied simultaneously.
The wake-waves generated by a ship making headway in a channel are of
several types. The short-period waves generated at the bow of the vessel, along with
the transverse stern wave, are developed because of the near-normal pressure
distribution along the hull. The bow wave is formed as the water is accelerated along
the flared portion of the bow and elevates the surface above the still-water level.
Along the sides of the vessel, the accelerated water is lowered in accordance with
Bernoulli’s principle, which requires that pressure decrease as velocity increases.
The transverse stern wave is formed by the return pressure and separation at the stern
of the vessel.
If the vessel is in a channel, long-period waves characterized as run-down and
the following run-up or surge wave may also develop. These waves are observed if
the draft of the vessel is greater than about half of the channel depth and a
considerable portion of the water in the channel are displaced as the vessel proceeds.
A large volume of water is pushed up at the bow of the vessel with an exaggerated
lowering of water level along the sides. The wave travels along the shoreline at the
speed of the ship and may provide a significant lowering of the water followed by an
run-up. Depending on the slope of the channel flanks, the run-down and run-up may
affect a large portion of the shore perpendicular to the waterline.
17
The three first waves were that reach the shoreline were identified as the
incident wave height (Bernard et al., 2002: Hong and Doi, 2006). These three first
waves are referred to as the primary wave packet. The interaction of the incident and
reflected waves on the bank leads to sediment entrainment and erosion on the terrace.
Sediment suspension needs about 3 to 5 minutes to settle back to ground level.
Heavy ship traffic has a great damaging potential in the vicinity of waterways
and the adjacent shoreline, in particular, in areas that are sheltered from large wind
waves such as wetlands, low-energy coasts (Bourne, 2000). On the other hand, it is
generally believed that ship wakes are negligible and that their effect is sporadic in
coastal areas that are open seawards and where natural waves are frequently much
higher than the wakes. This assumption is true for coasts exposed to high tides or
large wind waves indeed.
2.6
Navigation Channel
Deep-draft navigation refers to channel depths greater than 15 ft (4.57 m) and
shallow-draft refer to channel less than 15 ft. The depth of navigation channel
depends on the largest ship expected to use the harbour. The largest ships in service
are Ultra Large Crude Carrier (ULCC) tankers up to about 550,000 deadweight tons
(DWT). This size ship is usually used in dedicated trade routes, such as from the
Persian Gulf, around the Cape of Good Hope, and to offshore ports to serve Europe.
Ships of this size have drafts approaching 30.5 m (100 ft) and can enter none of the
major world ports.
Indications are that maximum bulk carrier ship sizes will get no larger, but
the average ship capacity will gradually increase as older ships are retired from
service. Bulk carriers and tankers up to about 55,000 DWT can call at ports with
18
12.2 m (40 ft) channel depths. Deepening to 15.2 m (50 ft) will provide access to
105,000 DWT ships (USACE, 2006).
Ship speeds are governed by ship control needs where wind, currents, and
waves would tend to reduce the control margins. An important consideration is the
minimum ship speed necessary to maintain adequate ship steerage; this is normally
four or more knots above the water current. Transit speeds from 5 knots to 10 knots
are the most common ship speed in typical harbour channels (USACE, 2006).
Figure 2.4: Cross Section of Pelabuhan Tanjung Pelepas Navigation Channel
Figure 2.4 shows the cross section of Pelabuhan Tanjung Pelepas. The depth
of the channel is always dredge to 17 m deep from Lowest Astronomical Tide
(LAT).
19
Vessels operating in restricted navigation channels can experience a variety
of effects (Figure 2.5). Large, loaded ships can block much of the channel cross
section and encounter very significant hydrodynamic resistance. Much of the water
in the channel cross section must flow around the passing ship through highly
confined space under the hull and between the hull and channel side slopes. Also,
the ship experiences resistance due to the waves it creates as it moves forward
(USACE, 2003).
Figure 2.5: Ship Wave and Flow Pattern in a Canal (Source: USACE, 2003)
In channel, water depth and ship speed are linked (Dand, 2004). This is due to
the large resistance experienced by ships when moving in sallow water at, or near,
the so-called critical speed vcrit for which the Froude Depth Number Fnh equals unity.
The minimum water depth must allow for:
a) maximum draught of the design vessel;
b) squat;
c) vertical motions due to waves and swell (heave, pitch and roll);
20
d) vertical motions induced by passing vessels;
e) seabed type (mud, silt, or hard bottom);
f) dredging tolerance (usually 0.1 to .6m). sounding accuracy is normally
about 0.2 m;
g) heel induced by wind or other factors;
h) water density; and
i) tidal variation.
Squat is the tendency for a vessel to change its under-keel clearance as it
moves ahead or astern, or is passed by another vessel close by. It derives from the
changes induced in the hydrodynamic pressure forces over the hull by the presence
of the seabed and/or by the presence of the other vessel. Squat may be estimated by
the following simple expression
Squat(m) = 2.4
∇
L2pp
Frd2
(1 − Fr )
2
d
where
∇
= volume of displacement (m3) = CB.Lpp.B.T
Lpp
= length between perpendiculars (m);
B
= beam;
D
= draught (m);
CB
= block coefficient; and
Frd
= Froude Depth Number
21
2.7
Erosion
Shoreline erosion is a process that occurs along all watercourses. There are
many natural causes such as wind-generated waves, water levels, ice, slope of the
bank, absence of vegetation, as well as human interference such as deforestation of
shorelines, wave action from assign boats. Based on rate of erosion and damage to
economic value, state of erosion is classified by National Coastal Erosion Study
(Economic Planning Unit, 1985) in three categories as stated in Table 2.1.
Table 2.1: Classification of Coastal Erosion
Category
Description
Critical
Shorelines currently in a state of erosion and where shore-based
facilities or infrastructure are in immediate danger of collapse or
damage;
Intermediate
Shorelines eroding at a rate whereby public property and
agriculture land of value will become threatened within 5 to 10
years unless remedial action is taken;
Acceptable
Undeveloped shorelines experiencing erosion but with no or
minor consequent economic loss if left unchecked.
Mangrove forest is one of the natural resources that exist in the coastal zone.
It is the most productive ecosystems on earth. Some of the benefits from mangrove
forests are as below:(i)
Protection of water quality
(ii)
Protection of coastal habitat
(iii)
Erosion control
(iv)
Protection of scenic and aesthetic quality
(v)
Timber product
22
Mangrove swamps are important in retarding coastal erosion and protecting
the coast. The swamps act as a system in which trees in all the zones have different
roles to play.
Damage to the system can result in irriversible coastal erosion.
Mangrove replanting can be successful if the mangroves are planted in the right
conditions. A lot failures can be attributed to mistakes such as planting on very low
mudflats and where the wave conditions are not favourable (Othman, 1991).
Shoreline mapping can be obtained from maps, charts and aerial photographs
(Committee on Coastal Erosion Zone Management, 1990). Maps and nautical charts
can be examined or superimposed to compare changes to the shoreline but are not
useful for exact erosion rate calculations because of the level of geographic control
results in errors that exceed the absolute amount of shoreline change.
2.8
Tidal Effect
Tides are the periodic motion of the waters of the sea due to changes in the
attractive forces of the moon and sun upon the rotating earth. A high tide may
provide enough depth for entering or leaving a harbour, while a low tide may prevent
it. At most places, the tidal change occurs twice daily. The tide rises until it reaches
a maximum height, called high tide or high water, and then falls to a minimum level
called low tide or low water.
Tides are classified as one of three types, semidiurnal, diurnal, or mixed,
according to the characteristics of the tidal pattern (Reeve D., Chadwick A. and
Fleming C., 2004). As a wave enters shallow water, its speed is decreased. Since the
trough is shallower than the crest, it is retarded more, resulting in a steepening of the
wave front. In a few estuaries, the advance of the low water trough is much retarded
that the crest of the rising tide overtakes the low, and advances upstream as a
breaking wave called a bore. Bores that are large and dangerous at times of large
23
tidal ranges may be mere ripples at those times of the month when the range is small
(IRBS website).
Tides are recorded in various datum. Generally, the tides are referred from
Mean Sea Level (MSL).
Tanjung Pelepas tide records are base from Lowest
Astronomical Tide (LAT) because it gives the lowest water tide datum. Tidal level
at standard Port in Malaysia (Pusat Hidrografi Nasional, 2008) can be referred to
different water level such as:
i.
Lowest Astronomical Tide
ii.
Mean Low Water Springs
iii.
Mean Low Water Neaps
iv.
Mean Sea Level
v.
Mean High Water Neaps
vi.
Mean High Water Springs
vii.
Highest Astronomical Tide
During high tide, the waves can reach the foot of mangrove forest of Tanjung
Piai but at low tide, the waves can reach only at certain level of the coastline. The
concern is during the high tide. The waves that reach the mangrove forest can uproot
the plants and diminish the natural wave breaker that the mangrove provides. This is
because the waves travel straight to the mangrove forest with no barrier at all.
Daidu Fan et al. (2006) conclude in his research that inter tidal mudflats can
be exposed to swells or local wind-driven waves.
modulated by tides.
Wave processes are greatly
Wave heights and the intensity of wave processes at the
intertidal mudflats are related to the local water depth regardless of incident wave
heights. The magnitude of erosion is greater for a weak storm during spring tides
than a strong storm during neap tides.
24
The redistribution of resuspended fine sediments out of the wave-breaking
zone is mainly controlled by tidal currents. Entrainment capacity of onshore currents
differs significantly from neap to spring tides, accounting for different erosion and
accretion models at the intertidal mudflat. Weak neap tidal currents tend to form the
middle accretion zone by rapidly settling of suspended sediment from high turbidity
water near the wave breaking zone, and the inner erosion zone by reforming waves.
Strong spring tidal currents transport more sediment farther out of the erosion
zone, resulting in higher erosion rate at the wave breaking zone and higher accretion
rate in the marshes. The lost materials can be replenished by huge riverine sediment
input, and the mudflat recovers to its quasi-equilibrium profile to normal wave
conditions in several tides after the typhoons.
CHAPTER 3
METHODOLOGY
Numerical analysis was performed to determine wave generation from ships,
wave propagation, wave transformation, and energy formation. A combination of
Blaauw et. al (1984), Knight (1999), Lord Kelvin (Thomson, 1887), Snell’s Law, and
Goda (1985) equations were used in this study. Erosion potential related to energy
from wave, ship traffic, and existing coastline protection was analysed and compared
to coastline change. Figure 3.1 shows the flow chart of study process.
3.1
Data Collection
Data collection for this research includes Tanjung Piai coastline changes,
profile of vessels, ship traffic, navigation channel, and existing coastal protection.
Profile of vessels and depth of navigation channel are necessary in the calculation
process.
The coastline changes data were taken from Coastal and Offshore
Engineering Institute (COEI) report.
The report was produced from aerial
photograph, map and chart analysis from year 1966 to 2000.
26
Profile of Vessels
Data
Wave Period
Depth of Channel
Wave Height
Wave Generation
Wave Celerity
Wave Length
Shoaling
Damping
Wave Propagation
Refraction
Breaking
Wave Period
Wave
Transformation
Wave Celerity
Wave Height
Wave Length
Energy Formation
Conclusion
Figure 3.1: Flow Chart of Study Process
Information of ship traffic, profile of vessels and navigation channel were
obtained from Jabatan Laut Semenanjng Malaysia (Wilayah Selatan). Ship traffic
statistic data was collected to determine the type of vessel entering and leaving PTP.
The profile of the vessels are very important to verify the magnitude of ship waves.
Such profiles are size of vessel, type, length, breath, maximum speed design,
and draft.
Types of vessels was randomly picked together with their profile
throughout a year from Jabatan Laut Malaysia database.
Important data on
navigation channel are the channel depth and distance from Tanjung Piai coastline,
27
which are achievable from the Malaysian Nautical Chart (Pusat Hidrografi National,
2005).
Monitoring program on geotube system and other coastal protection installed
at Tanjung Piai were collected from Jabatan Pengairan dan Saliran (JPS), Pontian.
Coastal protection needs monitoring program to make sure the effectiveness of the
system.
The system should dissipate wave energy and prevent the wave from
damaging the mangrove roots, provide mangrove sidling time to grow and to
accumulate sediment. The monitoring program will show the recent state of the
system and remedial action taken.
3.2
Calculations
3.2.1
Wave Generation
Wave generation from vessel calculated using modification of short period
wave equation by Blaauw et al (1984) and Knight (1999) expressed as:
1
B − 3 ⎛⎜ V
y
H1 = γ
⎜ g
LOA
⎝
⎞
⎟
⎟
⎠
2.67
where
H1
= reference wave height
y
= distance from sailing line (s = 100 m)
B
= vessel’s beam,
LOA
= vessel’s overall length
V
= vessel’s speed
28
g
= gravity acceleration
γ
= coefficient due to vessel size effect
Value of s was taken at 100 m as a reference point and γ can be calculated as
follows:
γ = 0.0002 × beam × draft
Calculation of propagation direction, θ was taken from Weggel and
Sorenson (1986) equation as below:
θ = 35.27(1 − e12( Fr −1) )
d
where
Frd
= depth Froude Number
and Frd was defined by
Frd =
V
gd
where
V
= vessel’s speed
g
= gravity acceleration
d
= channel depth
Wave celerity (C), wave length (L) and wave period (T) are then calculated
using Kelvin wedge theory (Thomson, 1887) by:
C = V cos θ
29
L=
2π 2
V cos 2 θ
g
T=
2π
V cos θ
g
where
3.2.2
V
= vessel’s speed
θ
= propagation direction
g
= gravity acceleration
Wave Propagation and Transformation
The incident wave angle, β relative to the x direction can be written as:
⎛ζ y ⎞
⎟⎟
⎝ζ x ⎠
β = tan −1 ⎜⎜
where
ζy
= vertical water surface elevation
ζx
= horizontal water surface elevation
The inclination of wave direction, tan β on the slope can be formulated as a
function of the distance from the sailing line, y. Based on Snell’s Law, the value of
tan β at a certain position is given by:
tan β =
(C / C1 × sin β1 )2
2
1 − (C / C1 × sin β1 )
30
where
C
= wave celerity
C1
= reference wave celerity
β1
= reference wave angle
Refraction, shoaling and damping was considered in wave transformation
calculation. The maximum wave height on slope calculated using proposed equation
by Dam et al. (2006) as follows:
[(
) ]
H max = min K sl × K rl × K dl × H1 , H b
where
K sl
= relative shoaling coefficient
K rl
= relative refraction coefficient
K dl
= relative damping coefficient
H1
= reference wave height
Hb
= breaking height
The minimum value of either K sl × K rl × K dl × H 1 or Hb are taken as the
maximum wave height. Breaking height will limit the wave from reaching the shore.
Breaking heights calculated using Goda (1970) equation as follows:
⎡
Hb
L ⎧⎪
πd
= 0.17 × o × ⎨1 − e ⎢− 1.5 b
db
db ⎪
Lo
⎢⎣
⎩
where
Lo
= deep water wave length
db
= breaking depth
β
= incident wave angle
4
⎞⎤ ⎫
⎛
⎜1 + 15 × β 3 ⎟⎥ ⎪⎬
⎟
⎜
⎠⎥⎦ ⎪⎭
⎝
31
The coefficients calculated as follows:
⎧⎪ ⎡ ⎛ C ⎞ 2 ⎤
⎫⎪
K = ⎨1 + ⎢1 − ⎜⎜ ⎟⎟ ⎥ tan 2 β 1 ⎬
⎪⎩ ⎢⎣ ⎝ C1 ⎠ ⎥⎦
⎪⎭
−1 / 4
l
r
⎛ y ⎞
K dl = ⎜
⎟
⎝ 100 ⎠
K sl =
−n
Ks
K s1
where
y
= distance from sailing line
n
= damping coefficient
Ks
= shoaling coefficient
K s1
= shoaling coefficient at y = 100
and
⎛d
K s = K si + 0.0015 × ⎜⎜
⎝ Lo
⎞
⎟⎟
⎠
−2.9
with
Ho =
Lo =
L=
and
gT 2
2π
H1
K s1
gT 2
2π
tanh
2πd
L
⎛H
× ⎜⎜ o
⎝ Lo
⎞
⎟⎟
⎠
1.3
32
1
K si =
tanh
2πd 2πd ⎛
2 2πd ⎞
+
⎜1 + tanh
⎟
L
L ⎝
L ⎠
where
3.2.3
Ho
= deep water wave height
K si
= shoaling coefficient at i = 1, 2, 3, …, n (n = 0.33)
Wave Energy
Finally, the energy flux, E from wave transformation simplified by:
E=
where
ρ
= water density
ρg 2 (H max )2 T 2
16π
CHAPTER 4
DATA ANALYSIS
4.1
Navigation Channel
Information about navigation channel is available from the Malaysian
Nautical Chart (Pusat Hidrografi National, 2005). The navigation channel is 400 m
wide to allow two-way access and always dredge to 17 m deep from Lowest
Astronomical Tide. The distance from Tanjung Piai and the navigation channel is
about 2400 m to 4600 m. Allowable speed approaching the port is not more than 12
knots (6.17m/s) as told by En. Abd Rahman Mohamad Yusof, Assistant Officer of
Aids to Navigation from Jabatan Laut Semenanjung Malaysia (Wilayah Selatan).
The recommended speeds are between 4 and 10 knots but an exception is given for
safety reason.
34
4.2
Profile of Vessels
List of vessels were picked randomly early each month from August 2006 to
August 2007. After sorting, 80 vessels were selected for the analysis considering
their size. Vessels with same profile were neglected because it will produce same
wave height. The selected vessels and its profile are listed in Table 4.1.
Table 4.1 : Profile of Vessels
No
Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Bright Gold
Charlotte Maersk
Cliffort Maersk
Columbine Maersk
Cosco Dammam
Csav California
Eagle Pride
Eleonora Maersk
Ever Ally
Ever Champion
Ever Gather
Ever Given
Ever Uranus
Gosport Maersk
Grete Maersk
Hansa London
Hatsu Ethic
Hatsu Smart
Hudson Strait
Indamex Colorado
Jinyunhe
Karen Maersk
Lady Fatima
Laguna
Lissy Schulte
Maersk Constantia
Maersk Dallas
Maersk Damascus
Maersk Danville
Maersk Dartmouth
Maersk Davao
Maersk Dayton
Maersk Djibouti
Max speed
(knots)
17.00
25.00
25.00
26.00
22.00
18.00
16.50
24.50
18.70
25.80
20.50
21.00
24.50
24.20
25.00
16.60
24.50
25.30
18.00
23.00
20.00
25.00
16.00
22.00
19.60
19.50
25.50
24.90
24.70
25.00
24.30
25.20
23.30
LOA
(m)
144.80
347.00
347.00
347.00
221.60
149.50
161.50
397.70
165.00
339.90
230.80
269.70
294.10
292.10
367.30
149.50
300.00
300.00
136.50
244.90
182.90
318.20
146.50
196.00
184.70
258.50
294.10
281.00
260.40
294.10
294.10
281.00
294.10
Beam
(m)
11.40
42.80
42.80
42.80
29.80
22.30
26.90
56.40
27.00
42.80
32.20
32.30
40.00
32.20
42.80
22.30
42.80
42.80
22.50
32.30
27.60
42.80
22.50
32.30
25.30
32.30
32.20
32.20
32.20
32.20
32.30
32.20
32.30
Draft
(m)
8.20
14.60
14.00
14.60
11.10
8.30
10.50
16.00
6.70
14.50
11.60
11.60
12.70
13.50
15.00
8.30
13.50
14.20
8.50
12.00
10.10
14.00
8.00
12.50
10.00
13.20
12.80
12.50
12.50
13.50
13.50
12.50
13.50
35
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
Maersk Drammen
Maersk Gloucester
Maersk Itea
Maersk Kalamata
Maersk Karachi
Maersk Kowloon
Maersk Kyrenia
Maersk Mytilini
Maersk Napier
Maersk Neustadt
Maersk Nolanville
Maersk Patras
Maersk Pembroke
Maersk Seoul
Maersk Surabaya
Maersk Tirana
Maersk Tokyo
Maersk Toyama
Martha Russ
Mekong Spirit
Mekong Valiance
Nedlloyd Africa
Nedlloyd Asia
Nedlloyd Dubai
Nedlloyd Hudson
Nicolai Maersk
Northern Felicity
Oel Freedom
Pacific Quest
Phu Tan
Pongola
Poseidon VII
Reverence
Rhoneborg
Rio Lawrence
SA Helderberg
Safmarine Pantanal
Sea Navigator
Sealand Innovator
Sealand Liberator
Sealand Mizhigan
Sezela
Skagen Maersk
Thomas Mann
Uni Accord
Uni Phoenix
Westerhever
24.50
24.50
22.00
25.00
24.50
24.00
25.00
26.10
21.00
20.70
22.00
21.00
22.50
25.40
25.40
25.50
24.00
24.00
20.00
18.10
14.00
23.50
23.50
23.00
25.30
22.00
19.20
17.00
17.00
17.80
18.00
21.00
18.00
18.00
19.00
18.00
19.60
18.60
20.70
20.70
26.00
18.50
25.00
22.70
18.70
18.90
20.00
282.10
292.10
242.00
304.20
299.00
299.50
300.00
294.30
207.40
207.40
210.00
210.40
210.10
332.40
332.00
260.70
269.80
255.70
148.00
149.50
113.20
266.30
266.30
258.50
277.70
198.60
174.50
156.60
158.90
157.70
133.20
202.60
142.30
173.60
149.00
258.50
147.80
167.20
257.50
257.50
300.40
133.20
347.00
213.00
165.00
181.80
168.00
32.20
32.20
32.20
40.00
42.50
40.30
42.50
32.20
29.80
29.80
30.20
32.20
32.20
43.20
43.20
32.30
32.20
32.20
23.50
22.30
19.10
32.20
32.30
32.30
40.00
30.20
27.40
24.00
23.00
22.90
20.80
30.10
22.60
28.80
22.70
32.30
23.50
25.00
30.60
30.70
40.00
20.80
42.80
32.20
27.10
28.00
26.70
12.00
13.50
12.00
14.00
14.00
14.00
14.00
13.50
11.40
11.40
11.50
12.50
12.50
14.50
14.50
12.00
13.00
13.00
8.50
8.30
8.50
12.50
12.50
13.00
14.00
11.00
9.90
8.30
10.10
8.60
7.80
11.20
8.00
8.00
7.80
11.20
8.50
9.80
10.70
10.00
14.00
7.80
14.00
10.50
6.70
9.00
10.80
36
The selected vessels were mainly container type.
The maximum speed
designed is 26.10 knots for Maersk Mytilini and the lowest speed is 14 knots of
Mekong Valiance. The lengths of vessels are in the range of 113.20 m to 397.70 m
and the beams are between 11.40 m and 56.40 m. The drafts are 7.80 m up to 16 m
in range. Longest, broadest and biggest draft vessel is Eleonora Maersk with the
speed of 24.50 knots.
4.3
Vessel Fleet
Vessel Fleet for Pelabuhan Tanjung Pelepas (PTP) are available from Jabatan
Laut Malaysia database. PTP has operated since 1999 but the data are only available
from 2001. Table 4.2 to Table 4.8 shows the number and type of vessel for each year
from 2001 to 2007.
Table 4.2: Total Vessel for Each Month in 2001
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
35
2
0
0
111
0
37
35
0
0
0
0
34
254
Feb Mar Apr May June July Aug Sept Oct Nov Dec
26
25
21
17
16
14
15
15
16
20
32
0
1
5
5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
0
0
0
0
5
122 164 138 167 152 158 165 162 171 148 158
0
1
21
2
6
3
1
2
0
0
0
29
50
43
43
52
53
44
41
43
45
39
35
27
36
55
53
64
61
67
70
68
69
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
1
1
1
1
0
2
0
0
2
0
0
0
0
0
0
0
4
1
4
22
15
22
12
9
6
8
7
8
14
38
237 283 288 303 289 299 295 294 314 296 346
37
Table 4.3: Total Vessel for Each Month in 2002
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
26
1
0
10
186
0
42
81
0
0
0
2
53
401
Feb Mar Apr May June July Aug Sept Oct Nov Dec
15
16
12
13
12
25
26
37
22
28
54
0
1
1
1
0
1
0
1
2
5
4
0
0
0
0
1
0
0
2
0
0
1
11
4
0
1
0
1
0
2
10
3
1
148 161 162 170 164 151 165 197 214 200 423
0
0
3
3
0
1
1
1
1
3
8
25
39
32
37
36
46
44
55
60
62 123
50
76
76
67
48
0
0
0
0
0
3
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
2
1
3
7
1
0
1
3
0
0
1
1
3
1
12
14
5
15
33
23
6
2
21
23
22
45
264 302 302 328 285 231 239 319 336 328 681
Table 4.4: Total Vessel for Each Month in 2003
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
33
1
0
4
211
4
60
1
0
0
1
10
24
349
Feb Mar Apr May June July Aug Sept Oct Nov Dec
20
28
32
32
41
44
29
38
30
31
41
1
3
6
6
6
7
6
6
14
14
10
1
4
0
0
0
0
1
0
2
5
3
3
8
9
7
1
7
2
6
4
1
1
163 218 204 208 208 227 225 208 214 218 214
7
5
5
10
11
15
10
9
7
7
9
47
48
47
46
41
55
57
55
61
61
68
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
2
0
0
3
0
0
0
0
0
0
0
0
0
1
0
0
0
0
2
2
2
2
1
6
4
4
5
4
8
6
3
3
5
1
1
4
1
0
0
86
26
28
28
41
46
36
43
44
39
56
336 348 337 342 356 405 373 375 384 381 406
38
Table 4.5: Total Vessel for Each Month in 2004
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
37
16
0
0
211
24
63
1
0
0
3
0
45
400
Feb Mar Apr May June July Aug Sept Oct Nov Dec
46
60
89
66
47
31
32
25
25
17
18
16
21
12
10
18
11
11
6
4
5
20
0
1
0
0
6
1
4
30
3
3
2
0
0
0
0
0
0
0
0
0
1
0
189 213 203 215 202 201 219 210 238 217 222
23
28
37
29
15
15
16
19
5
13
12
57
71
63
77
66
71
78
87 107 97 110
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
3
5
4
2
4
2
5
4
6
2
1
1
1
0
1
1
1
0
0
0
0
56
78
86
67
73
50
38
41
35
24
14
390 476 496 468 430 385 401 423 421 383 400
Table 4.6: Total Vessel for Each Month in 2005
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
91
36
5
0
276
15
157
0
0
0
5
1
23
609
Feb Mar Apr
19
72
19
20
23
17
2
2
3
0
0
0
197 220 204
12
21
23
111 143 163
1
0
0
0
0
0
0
0
0
2
3
2
0
0
0
12
18
11
376 502 442
May
24
24
4
1
217
23
174
0
0
0
2
0
17
486
June
32
18
2
0
215
34
146
0
0
0
4
12
37
500
July
25
17
2
0
218
26
149
0
0
0
4
10
20
471
Aug
30
25
2
0
223
16
175
0
0
0
4
2
35
512
Sept
22
21
1
0
213
22
156
0
0
0
5
0
22
462
Oct Nov Dec
78
32
19
24
29
17
4
2
3
2
0
1
514 418 233
24
24
22
289 251 171
1
0
0
0
0
0
4
0
0
2
1
0
0
4
0
20
17
10
962 778 476
39
Table 4.7: Total Vessel for Each Month in 2006
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
47
33
6
0
449
18
276
0
0
0
1
0
15
845
Feb Mar Apr
22
18
18
19
14
14
3
4
1
4
4
1
279 269 235
15
10
7
172 179 179
0
0
0
0
0
0
3
0
0
3
0
2
0
0
0
7
8
8
527 506 465
May
22
16
0
1
235
8
194
0
0
0
2
0
12
490
June
17
15
0
3
265
5
181
0
0
0
0
0
12
498
July
20
10
3
1
252
10
194
0
1
0
2
1
12
506
Aug
14
8
5
2
251
11
182
0
0
7
1
0
7
488
Sept
4
2
0
1
237
13
218
1
0
15
0
1
5
497
Oct Nov Dec
4
4
8
0
2
2
0
0
2
1
1
2
257 254 274
15
11
7
191 190 197
0
0
1
0
0
1
0
0
0
0
0
0
0
1
0
7
4
7
475 467 501
Table 4.8: Total Vessel for Each Month in 2007
TYPE/MONTH Jan
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
4
1
0
3
278
10
185
1
0
0
0
4
8
494
Feb Mar Apr
5
6
3
0
1
1
0
2
3
4
1
4
255 279 288
26
20
19
181 242 200
0
0
0
0
0
0
0
0
0
0
2
1
5
1
0
7
9
4
483 563 523
May
14
0
2
4
308
12
206
0
0
0
0
0
7
553
June
7
4
2
2
289
20
234
0
0
0
0
0
17
575
July
3
3
0
2
310
6
259
1
0
0
1
2
12
599
Aug
1
2
2
3
417
5
234
0
0
0
0
1
8
673
Sept
7
7
2
3
293
8
231
0
0
0
0
1
3
555
Oct Nov Dec
3
6
9
4
3
4
2
1
1
3
3
2
318 292 303
6
6
8
204 210 186
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
4
19
15
545 541 528
40
Table 4.9: Total Vessel for 2001 to 2007
TYPE/YEAR
Barge
Barge Carrier
Boat
Dry Bulk
Full Container
General Cargo
Liquid Bulk
Passenger
Leasure Craft
Ro-ro
Semi Container
Supply Vessel
Tug Boat
Total
2001
252
13
1
7
1,816
36
519
640
0
0
8
11
195
3,498
2002
286
17
4
43
2,341
21
601
401
1
0
14
25
262
4,016
2003
399
80
16
53
2,518
99
646
3
5
1
33
42
497
4,392
2004
493
150
50
1
2,540
236
947
1
0
0
42
6
607
5,073
2005
463
271
32
4
3,148
262
2,085
2
0
4
34
29
242
6,576
2006
198
135
24
21
3,257
130
2,353
2
2
25
11
3
104
6,265
2007
68
30
17
34
3,630
146
2,572
3
0
0
4
15
113
6,632
Vessel Fleet for 2001 to 2007
7000
6000
Tug Boat
Supply Vessel
Semi Container
Ro-ro
Leasure Craft
Passenger
Liquid Bulk
General Cargo
Full Container
Dry Bulk
Boat
Barge Carrier
Barge
Total Vessel
5000
4000
3000
2000
1000
0
2001
2002
2003
2004
2005
2006
2007
Year
Figure 4.1: Vessel Fleet from 2001 to 2007
The total of vessels increases each year except for 2006 (Figure 4.1). The
highest contribution is full container type vessel followed by liquid bulk.
The
number of full container and liquid bulk increases correlated to the increases of the
total vessels. Barge and tug boat increases slightly until 2004, and decrease in 2005,
41
2006 and 2007. In 2001 and 2002, there are a number of passenger type vessels.
Other vessel does not give any significant value.
4.4
Shoreline Change
Numbers in the circles are the references area of the studied erosion rate by
COEI (Figure 4.2) for Tanjung Piai. The number in negative value shows the rate of
erosion. Area 1 is having the highest erosion rate of 15 m/yr. Area 2 gives the
second highest erosion rate of 10.5 m/yr. Taman Negara Tanjung Piai is located
within Area 1 and Area 2.
9
-5.2 m/yr
-5.5 m/yr
-2.8 m/yr
8
7
6
5
4
-1.8 m/yr
-3.9 m/yr
-4.4 m/yr
3
-6.4 m/yr
2
-10.5 m/yr
1
-15 m/yr
Figure 4.2: Erosion Rate (Reported by COEI)
The rate of erosion is smaller at the bay and higher at the headland. This is
true to the theory of refraction. The increasing rate of erosion can be seen by the
chronology of Area 6 to Area 1 and Area 6 to Area 8 with the exception of Area 9.
42
4.5
Existing Coastal Protection
N
Jabatan Pengairan dan Saliran (JPS), Malaysia has conducted a study to
control erosion along Tanjung Piai coastline. The coastline of east Tanjung Piai is
about 8 km from area 1 to area 9 in Figure 4.2. Summary of data and result of the
study are shown in Table 4.10 below. Big ships generate small but high frequency
wave. The wave height is about 0.5 m and the wave period is 4 to 5 seconds.
Tanjung Piai receive dominant wave from north ranging from 1.2m to 1.7m height.
The wave height increases during storm event. Figure 4.3 to Figure 4.5 shows the
wave and direction generated by wind
Table 4.10: Summary of Data and Result of Study by JPS, Malaysia
Highest Astronomical Tide
Mean High Water
Mean Low Water
Lowest Astronomical Tide
Average Wind Speed
Wave Period
Wave Height
+1.90 m (LSD)
+1.33 m (LSD)
-1.33 m (LSD)
-1.80 m (LSD)
7 – 9 m/s
4 – 8sec
1.2 m to 1.7 m
Observation by Taman Negara Tanjung Piai agency (2007), erosion on
Tanjung Piai has been noticed since 1992, and worsens from year 2002. Several
places of critical condition have been identified and Table 4.11 shows the erosion
control projects carried by JPS, Malaysia.
Table 4.11: Erosion Control Projects along Taman Negara Tanjung Piai
No
1
2
3
4
5
6
Project
Geotube Phase I
Geotube Phase II
Geotube Phase III
Seawall (Wellguard)
Rock Revertment
Rock Revertment
Length
200
400
900
123
90
90
Date of Completion
15/12/03
11/08/05
8/06/06
30/09/2006
19/12/07
Dec 2007
43
Figure 4.3: Wave Height and direction (at 180ο) (Source: JPS, 2005)
44
Figure 4.4: Wave Height and direction (at 120ο) (Source: JPS, 2005)
45
Figure 4.5: Wave Height and direction (at 150ο) (Source: JPS, 2005)
46
Figure 4.6: Alignment of Geotubes (Source: JPS, 2005)
Geotubes has been chosen to ptotect the coastline according to site condition,
ecosystem and engineering factors. It is a high quality geotextile sewn like a tube
with 1.8 meter diameter and filled with sand. It is installed 20 m from the shoreline
and act as wave breaker. Monitoring program has been carried out starting from
December 2005 until May 2007. Figure 4.6 shows the alignment of the Geotubes in
three fhases. Stick gauges were burried one meter behind the geotubes in eleven
places to record the bed level (Figure 4.7) to monitor the accretion and depletion rate.
There are several missing data because some problems occur regarding the stick
gauge (Table 4.12).
47
Figure 4.7: Location of Stick Gauge (Source: JPS, 2005)
The monitoring program shows some accretion behind the geotubes but more
time are needed to see full result. Currently, the geotubes provide 10% to 30%
reduction to erosion (Figure 4.8).
Therefore, Taman Negara Tanjung Piai
corporation has request from JPS an additional erosion protection work for other
critical location. Figure 4.9 to Figure 4.11 show the condition behind the geotubes
after the installation of geotubes. Monitoring program for coastal protection work
should be at least for three years but the program has to stop because of some
difficulties. A calm water can be seen behind the geotubes from Figure 4.11. Figure
4.12 shows one of the stick gauge behind the geotubes.
48
Table 4.12: Bed Level Reading Behind Geotubes
Stick Gauge No.
Month/Year
No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 No. 10 No.11
Dec 05
Jan 06
Feb 06
Mar 06
Apr 06
May 06
June 06
July 06
Aug 06
Sept 06
Oct 06
Nov 06
Dec 06
Jan 07
Feb 07
Mar 07
Apr 07
May 07
-0.42
-0.31
-0.34
-0.37
-0.21
-0.38
-0.15
-0.29
-0.21
-0.2
-0.29
-0.34
-0.26
-0.29
-0.21
-0.39
-0.23
-0.21
-0.38
-0.38
-0.2
-0.12
-0.28
-0.13
-0.29
-0.11
-0.2
-0.1
-0.26
-0.18
-0.2
-0.13
-0.22
-0.23
-0.2
-0.4
-0.38
-0.49
-0.33
-0.31
-0.48
-0.18
-0.29
-0.31
-0.2
-0.24
-0.3
-0.25
-0.29
-0.33
-0.36
-0.21
-0.2
-0.55
-0.49
-0.42
-0.4
-0.43
-0.49
-0.2
-0.18
-0.38
-0.4
-0.35
-0.43
-0.38
-0.32
-0.37
-0.29
-0.26
-0.4
-0.55
-0.51
-0.55
-0.58
-0.38
-0.48
-0.38
-0.22
-0.39
-0.42 -0.42
-0.48
-0.32
-0.39
-0.42
-0.15
-0.12
-0.39
-0.45
-0.38
-0.44
-0.35
-0.38
-0.32
-0.27
-0.24
-0.5
-0.4
-0.48
-0.55
-0.48
-0.48
-0.48
-0.38
-0.22
-0.37
-0.3
-0.37
-0.3
-0.39
-0.32
-0.35
-0.29
-0.4
-0.48
-0.55
-0.48
-0.24
-0.3
-0.37
-0.24
-0.39
-0.3
-0.4
-0.33
-0.38
-0.3
-0.37
-0.26
-0.31
-0.3
-0.4
-0.48
-0.41
-0.38
0.2
0.22
0.1
-0.09
-0.05
-0.15
-0.1
-0.02
0.1
0.12
0.11
0.05
-0.1
-0.2
Time (mmyr)
Gauge2
Gauge3
Gauge4
Gauge5
Gauge8
Gauge9
Gauge10
Gauge11
Figure 4.8: Bed Level Reading Behind Geotubes
Gauge1
Mei 07
Apr 07
Mar 07
Feb 07
Jan 07
Dec 06
Nov 06
Oct 06
Sept 06
Aug 06
July 06
June 06
Mei 06
Apr 06
Mar 06
Feb 06
Jan 06
0.3
0.2
0.1
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
Dec 05
Depth (m)
Bed Level Reading Behing Geotubes
49
Figure 4.9: Condition Behind Geotubes on July 2004 (Source: JPS, 2005)
Figure 4.10: Condition Behind Geotubes on November 2004 (Source: JPS, 2005)
50
Figure 4.11: Condition Behind Geotubes on April 2005 (Source: JPS, 2005)
Figure 4.12: Stick Gauge (Source: JPS, 2005)
51
4.6
Sample of Calculations
4.6.1
Speed of Vessel
Given speed, V = 12 knots
Convert in unit meter per second,
1 knot = 0.514 m/s
12 × 0.514 = 6.17 m/s
4.6.2 Depth Froude Number
Frd =
V
gd
Given speed, V = 6.17 m/s, and channel depth, d = 17 m,
Frd =
4.6.2
6.17
9.81(17 )
= 0.48
Wave Propagation Direction
θ = 35.27(1 − e12( Fr −1) )
d
(
= 35.27 1 − e12(0.48−1)
= 35.20°
)
52
4.6.3
Wave Period
T=
=
2π
V cos θ
g
2π
(6.17 ) cos(35.20)
9.81
= 3.23s
4.6.4
Celerity
C = V cos θ
= 6.17 cos(35.20)
= 5.04m / s
4.6.5
Wave Length
L=
=
2π 2
V cos 2 θ
g
2π
(6.17 )2 cos 2 (35.20 )
9.81
= 16.27 m
53
4.6.6
Wave Height
1
B − 3 ⎛⎜ V ⎞⎟
H1 = γ
y
⎜ g⎟
LOA
⎝
⎠
2.67
From Table 4.1, for vessel no 1:
Beam, B
= 11.40 m
Overall Length, L
= 144.80 m
Draft
= 8.20 m
Speed, V
= 6.17 m/s
Gravity acceleration, g
= 9.81 ms-2
γ = 0.0002 × beam × draft
= 0.0002 × 11.40 × 8.20
= 0.0187
For y = 100,
1
11.40 − 3 ⎛ 6.17 ⎞
H 1 = 0.0187
s ⎜⎜
⎟⎟
144.80
⎝ 9.81 ⎠
4.6.7
Beach slope
⎛ζ y ⎞
⎟⎟
ζ
⎝ x⎠
β = tan −1 ⎜⎜
⎛ 2 ⎞
= tan −1 ⎜
⎟ = 0.115°
⎝ 1000 ⎠
2.67
= 0.029m
54
4.6.8
Wave Transformation
i)
Relative shoaling coefficient
1
K si =
2πd 2πd ⎛
2 2πd ⎞
+
⎜1 + tanh
⎟
L
L ⎝
L ⎠
tanh
1
K s1 =
2π (17 ) 2π (17 ) ⎛
2 2π (17 ) ⎞
+
⎜1 + tanh
⎟
16.27 16.27 ⎝
16.27 ⎠
tanh
= 0.266
Ho =
H 1 0.029
=
= 0.109
K s1 0.266
⎛d
K s = K s1 + 0.0015 × ⎜⎜
⎝ Lo
⎞
⎟⎟
⎠
−2.9
⎛H
× ⎜⎜ o
⎝ Lo
⎛ 17 ⎞
= 0.266 + 0.0015 × ⎜
⎟
⎝ 16.27 ⎠
= 0.266
K sl =
ii)
K s 0.266
=
= 1.0
K s1 0.266
Relative damping coefficient
−n
⎛ y ⎞
K =⎜
⎟ , n = 0.33
⎝ 100 ⎠
l
d
For y = 200 m from the sailing line
⎛ 200 ⎞
K dl = ⎜
⎟
⎝ 100 ⎠
−0.33
= 0.796
−2.9
⎞
⎟⎟
⎠
1.3
⎛ 0.109 ⎞
×⎜
⎟
⎝ 16.27 ⎠
1.3
55
4.6.9
Breaking height
⎡
Hb
L ⎧⎪
πd
= 0.17 × o × ⎨1 − e ⎢− 1.5 b
db
db ⎪
Lo
⎢⎣
⎩
Using trial and error technique, find
Hb
> 0.78
db
H b = 0.78 × d b
For db = 1.53,
H b = 0.78 × 1.53 = 1.193m
4.6.10 Maximum wave height
[(
) ]
H max = min K sl × K rl × K dl × H1 , H b
K sl × K dl × H 1 = 1.0 × 0.796 × 0.029
= 0.023
K sl × K dl × H 1 < H b , so Hmax = 0.023 m
4
⎛
⎞⎤ ⎫
⎜1 + 15 × β 3 ⎟⎥ ⎪⎬
⎜
⎟
⎝
⎠⎥⎦ ⎪⎭
56
4.6.11 Wave Energy
E=
ρg 2 (H max )2 T 2
16π
Water density ρ = 1000 kg/m3
g = 9.81 m/s2
T = 3.23 s
For Hmax = 0.023 m,
1000(9.81) (0.023) (3.23)
16π
2
E=
2
2
= 10.55kJ / m
4.7
Results
Table 4.13 shows the values of ship wave properties in deep water. For the
limited speed of 6.17 m/s, the depth Froude Number is 0.48, which is in the
subcritical value.
The direction of propagation is 35.20ο for both inbound and
outbound trip because it depends on the depth Froude Number. The wave length,
wave period and celerity is 16.27 m, 3.23 s and 5.04 m/s respectively. The values
show that ship wave at PTP is a deep water wave because of the short wave length
proportional to the channel depth and it produce short period wave. Table 4.14
shows the wave heights generated by ships.
57
Table 4.13: Properties of Deep Water Ship Waves
Properties
Channel Depth
Vessel Speed, V
Depth Froude Number, Fd
Wave Propagation Direction, θ
Wave Length, L
Wave Period, T
Celerity, C
Values
17 m
6.17 m/s
0.48
35.20ο
16.27 m
3.23 s
5.04 m/s
Table 4.14: Wave Heights Generated by Ships
Vessel No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Name
Bright Gold
Charlotte Maersk
Cliffort Maersk
Columbine Maersk
Cosco Dammam
Csav California
Eagle Pride
Eleonora Maersk
Ever Ally
Ever Champion
Ever Gather
Ever Given
Ever Uranus
Gosport Maersk
Grete Maersk
Hansa London
Hatsu Ethic
Hatsu Smart
Hudson Strait
Indamex Colorado
Jinyunhe
Karen Maersk
Lady Fatima
Laguna
Lissy Schulte
Maersk Constantia
Maersk Dallas
Maersk Damascus
Maersk Danville
Maersk Dartmouth
Maersk Davao
Maersk Dayton
Maersk Djibouti
LOA (m) Beam (m) Draft (m)
144.80
11.40
8.20
347.00
42.80
14.60
347.00
42.80
14.00
347.00
42.80
14.60
221.60
29.80
11.10
149.50
22.30
8.30
161.50
26.90
10.50
397.70
56.40
16.00
165.00
27.00
6.70
339.90
42.80
14.50
230.80
32.20
11.60
269.70
32.30
11.60
294.10
40.00
12.70
292.10
32.20
13.50
367.30
42.80
15.00
149.50
22.30
8.30
300.00
42.80
13.50
300.00
42.80
14.20
136.50
22.50
8.50
244.90
32.30
12.00
182.90
27.60
10.10
318.20
42.80
14.00
146.50
22.50
8.00
196.00
32.30
12.50
184.70
25.30
10.00
258.50
32.30
13.20
294.10
32.20
12.80
281.00
32.20
12.50
260.40
32.20
12.50
294.10
32.20
13.50
294.10
32.30
13.50
281.00
32.20
12.50
294.10
32.30
13.50
γ
0.0187
0.1250
0.1198
0.1250
0.0662
0.0370
0.0565
0.1805
0.0362
0.1241
0.0747
0.0749
0.1016
0.0869
0.1284
0.0370
0.1156
0.1216
0.0383
0.0775
0.0558
0.1198
0.0360
0.0808
0.0506
0.0853
0.0824
0.0805
0.0805
0.0869
0.0872
0.0805
0.0872
B/LOA
0.0787
0.1233
0.1233
0.1233
0.1345
0.1492
0.1666
0.1418
0.1636
0.1259
0.1395
0.1198
0.1360
0.1102
0.1165
0.1492
0.1427
0.1427
0.1648
0.1319
0.1509
0.1345
0.1536
0.1648
0.1370
0.1250
0.1095
0.1146
0.1237
0.1095
0.1098
0.1146
0.1098
H
0.029
0.307
0.294
0.307
0.177
0.110
0.187
0.510
0.118
0.311
0.208
0.179
0.275
0.191
0.298
0.110
0.328
0.345
0.126
0.204
0.168
0.321
0.110
0.265
0.138
0.212
0.180
0.184
0.198
0.190
0.191
0.184
0.191
58
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
Maersk Drammen
Maersk Gloucester
Maersk Itea
Maersk Kalamata
Maersk Karachi
Maersk Kowloon
Maersk Kyrenia
Maersk Mytilini
Maersk Napier
Maersk Nolanville
Maersk Neustadt
Maersk Patras
Maersk Pembroke
Maersk Seoul
Maersk Surabaya
Maersk Tirana
Maersk Tokyo
Maersk Toyama
Martha Russ
Mekong Spirit
Mekong Valiance
Nedlloyd Africa
Nedlloyd Asia
Nedlloyd Dubai
Nedlloyd Hudson
Nicolai Maersk
Northern Felicity
Oel Freedom
Pacific Quest
Phu Tan
Pongola
Poseidon VII
Reverence
Rhoneborg
Rio Lawrence
Sa Helderberg
Safmarine Pantanal
Sea Navigator
Sealand Innovator
Sealand Liberator
Sealand Mizhigan
Sezela
Skagen Maersk
Thomas Mann
Uni Accord
Uni Phoenix
Westerhever
282.10
292.10
242.00
304.20
299.00
299.50
300.00
294.30
207.40
210.00
207.40
210.40
210.10
332.40
332.00
260.70
269.80
255.70
148.00
149.50
113.20
266.30
266.30
258.50
277.70
198.60
174.50
156.60
158.90
157.70
133.20
202.60
142.30
173.60
149.00
258.50
147.80
167.20
257.50
257.50
300.40
133.20
347.00
213.00
165.00
181.80
168.00
32.20
32.20
32.20
40.00
42.50
40.30
42.50
32.20
29.80
30.20
29.80
32.20
32.20
43.20
43.20
32.30
32.20
32.20
23.50
22.30
19.10
32.20
32.30
32.30
40.00
30.20
27.40
24.00
23.00
22.90
20.80
30.10
22.60
28.80
22.70
32.30
23.50
25.00
30.60
30.70
40.00
20.80
42.80
32.20
27.10
28.00
26.70
12.00
13.50
12.00
14.00
14.00
14.00
14.00
13.50
11.40
11.50
11.40
12.50
12.50
14.50
14.50
12.00
13.00
13.00
8.50
8.30
8.50
12.50
12.50
13.00
14.00
11.00
9.90
8.30
10.10
8.60
7.80
11.20
8.00
8.00
7.80
11.20
8.50
9.80
10.70
10.00
14.00
7.80
14.00
10.50
6.70
9.00
10.80
0.0773
0.0869
0.0773
0.1120
0.1190
0.1128
0.1190
0.0869
0.0679
0.0695
0.0679
0.0805
0.0805
0.1253
0.1253
0.0775
0.0837
0.0837
0.0400
0.0370
0.0325
0.0805
0.0808
0.0840
0.1120
0.0664
0.0543
0.0398
0.0465
0.0394
0.0324
0.0674
0.0362
0.0461
0.0354
0.0724
0.0400
0.0490
0.0655
0.0614
0.1120
0.0324
0.1198
0.0676
0.0363
0.0504
0.0577
0.1141
0.1102
0.1331
0.1315
0.1421
0.1346
0.1417
0.1094
0.1437
0.1438
0.1437
0.1530
0.1533
0.1300
0.1301
0.1239
0.1193
0.1259
0.1588
0.1492
0.1687
0.1209
0.1213
0.1250
0.1440
0.1521
0.1570
0.1533
0.1447
0.1452
0.1562
0.1486
0.1588
0.1659
0.1523
0.1250
0.1590
0.1495
0.1188
0.1192
0.1332
0.1562
0.1233
0.1512
0.1642
0.1540
0.1589
0.176
0.191
0.205
0.293
0.337
0.302
0.336
0.189
0.194
0.199
0.194
0.245
0.246
0.324
0.325
0.191
0.199
0.210
0.126
0.110
0.109
0.194
0.195
0.209
0.321
0.201
0.170
0.122
0.134
0.114
0.101
0.200
0.114
0.152
0.107
0.180
0.127
0.146
0.155
0.146
0.297
0.101
0.293
0.204
0.119
0.155
0.183
59
Wave Heights Generated by Ships
0.60
Wave Height, H (m)
0.50
0.40
0.30
0.20
0.10
0.00
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
Vessel No.
Figure 4.13: Wave Heights Generated by Ships
Figure 4.13 shows that different vessels generated different wave height.
Vessels with bigger draft, broader and lengthier generate bigger wave.
Wave
generated is between 0.029 m and 0.51 m for this study. This results is consistent
with the study by Jabatan Pengairan dan Saliran (JPS) (Refer section 4.5). Waves
generated by vessels are smaller than waves generated by wind which is between 1.2
m to 1.7 m.
Wave Height vs Vessel's Length, Beam and Draft
Draft (m)
0
2
4
6
8
10
12
14
16
18
0.6
Wave Height, H (m)
0.5
0.4
0.3
R2 = 0.6733
2
R2 = 0.7414
R = 0.9313
0.2
Length
0.1
Beam
Draft
0.0
0
50
100
150
Beam (m)
200
250
300
350
400
450
Length (m)
Figure 4.14: Correlation between Wave Height, Beam, Length and Draft of Vessel
60
The R2 value from Figure 4.14 shows the correlation between wave height
and beam, length and draft of vessels. The nearest value of R2 = 1 have the highest
correlation. The correlations show that wave height depends more to vessel’s beam
than vessel’s draft and length.
Table 4.15: Wave Frequency, Minimum, Average and Maximum Value
Wave Range (m)
0.00 – 0.05
0.05 – 0.10
0.10 – 0.15
0.15 – 0.20
0.20 – 0.25
0.25 – 0.30
0.30 – 0.35
0.35 – 0.40
0.40 – 0.45
0.45 – 0.50
0.50 – 0.55
Frequency
1
0
20
28
11
7
12
0
0
0
1
Max (m)
0.029
0
0.146
0.199
0.246
0.298
0.345
0
0
0
0.510
Average (m)
0.029
0
0.119
0.183
0.213
0.288
0.322
0
0
0
0.510
Min (m)
0.029
0
0.101
0.152
0.200
0.265
0.302
0
0
0
0.510
Wave Frequency, Minimum, Average and Maximum Value
0.6
0.510
25
0.4
20
Frequency
0.5
0.322
15
0.3
0.288
0.213
10
0.2
0.183
0.119
5
0.1
0.029
0.0
0
0.025
0.075
0.125
0.175
0.225
0.275
0.325
0.375
0.425
0.475
0.525
Average Wave Range
Frequency
Max
Average
Min
Figure 4.15: Wave Frequency, Minimum, Average and Maximum Value
Wave Height, H (m)
30
61
From Table 4.15 and Figure 4.15, the average highest frequency wave is
0.183, followed by 0.119 m, 0.322 m, 0.213 m, and 0.288 m respectively. The range
of wave height at 0 to 0.05 m and 0.50 to 0.55 m are rare. Conclusively, frequent
waves generated by ships are in the range of 0.10 m to 0.35 m.
Table 4.16: Wave Period, Length and Celerity at Certain Depth
d
17
10
9
8
7
6
5
4
3
2
1
0.5
0.4
0.3
0.2
0.1
T
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
3.23
L
16.269
16.255
16.238
16.203
16.130
15.981
15.687
15.135
14.150
12.452
9.457
6.917
6.229
5.431
4.462
3.178
C
5.040
5.036
5.030
5.020
4.997
4.951
4.860
4.689
4.384
3.858
2.930
2.144
1.930
1.682
1.383
0.984
d/L
1.045
0.615
0.554
0.494
0.434
0.375
0.319
0.264
0.212
0.161
0.106
0.072
0.064
0.055
0.045
0.031
Wave Type
deep
deep
deep
inter
transitional
transitional
transitional
transitional
transitional
transitional
transitional
transitional
transitional
transitional
shallow
shallow
Table 4.16 shows wave period, wave length and celerity at certain depth
when the waves propagate from the navigation channel to Tanjung Piai and the
transformation occurs. Wave period remain constant during the process but wave
length and celerity decrease as the depth decrease.
Table 4.17 shows the beach slope, breaker depth, breaker height, and
breaking type for inbound trip and outbound trip. The slope of the beach is 0.041 to
2.862 and considered very mild. The breaker type is spilling for inbound and
outbound trip. Figure 4.16 shows the sailing line and direction of propagation of
inbound and outbound trip from the bathymetry map.
62
Table 4.17: Beach Slope, Breaker Depth, Breaker Height, and Breaking Type
β1
tan β
2.862
0.955
0.573
0.286
0.191
0.143
0.115
0.095
0.082
0.072
0.050
0.017
0.010
0.005
0.003
0.002
0.002
0.002
0.001
0.001
0.716
0.573
0.286
0.191
0.143
0.115
0.095
0.082
0.072
0.064
0.057
0.052
0.048
0.044
0.041
0.012
0.010
0.005
0.003
0.002
0.002
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
d
Hb
Inbound Trip
1.53
1.193
0.57
0.445
0.39
0.304
0.26
0.203
0.23
0.179
0.21
0.164
0.2
0.156
0.19
0.148
0.18
0.140
0.18
0.140
Outbound Trip
0.45
0.351
0.39
0.304
0.26
0.203
0.23
0.179
0.21
0.164
0.2
0.156
0.2
0.156
0.19
0.148
0.19
0.148
0.19
0.148
0.19
0.148
0.18
0.140
0.18
0.140
0.18
0.140
0.18
0.140
ξb
Breaking Type
0.057
0.019
0.011
0.006
0.004
0.003
0.002
0.002
0.002
0.001
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
0.014
0.011
0.006
0.004
0.003
0.002
0.002
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
spilling
63
Lagend:
Sailing Line
Propagation Direction (Inbound)
Propagation Direction (Outbound)
Figure 4.16: Bathymetry Map (Source: JPS, 2005)
Figure 4.17 shows the breaker limit at Tanjung Piai coastline. Certain waves
will breaks when it exceeds the limit. Most waves will break near the shoreline and
the breaker depth is between 0.18 m to 1.53 m. Breaker heights is in the range of
0.14 m and 1.19 m.
64
Breaker Limit
1.4
Breaker Height, Hb (m)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Breaker Depth, db (m)
Figure 4.17: Breaker Depth at Certain Beach Slope
Wave Transformation
0.7
Wave Height, H (m)
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Distance from Sailing Line, y (m)
H1=0.510
H1=0.322
H1=0.288
H1=0.213
H1=0.183
H1=0.119
H1=0.029
Breaker Line
Figure 4.18: Waves Transformation
Wave decay gradually away from sailing line (Figure 4.18) due to damping
and increase near the shore due to shoaling. At a certain depth, bigger waves will
breaks and dissipate. Smaller waves reach the shore without breaking. Maximum
wave height that reaches the shore is 0.112 m from the frequent wave height of
0.119.
65
Energy from Wave
70000
60000
Energy, E (kJ/m)
50000
40000
30000
20000
10000
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Wave Height, H (m)
Figure 4.19: Energy from Wave
Energy from waves related to the power of wave height as shown in Figure
4.19. Bigger waves will produce higher energy. Wave height from wind is between
1.2 m and 1.7 m, and wind wave produced higher energy than ship wave. Highest
energy is 58000 kJ/m at wave height of 1.7.
CHAPTER 5
CONCLUSIONS AND RECOMMENDATIONS
5.1
Conclusions
Based on allowable speed of 12 knots, the depth Froude Number for the
channel system is 0.48 and it shows that the channel is in subcritical condition. For
the same depth Froude Number, each vessels will produce the same propagation
direction, celerity, wave length and wave period but different wave height. Deep
water wave length, wave period, celerity, and wave propagation direction are 16.27
m, 3.2 s, 0.48, 5.04 m/s and 35.20ο respectively.
The generated wave heights depend on the length, beam, and draft of the
vessels. Broader vessel will generate bigger wave than bigger draft vessel and bigger
draft vessel will generate bigger wave than longer vessel. The wave heights are
between 0.029 m and 0.51 m but frequent waves are in the range of 0.10 m to 0.35
m.
67
Shoaling and damping take effect when the waves propagate to the shore but
there is no effect from refraction because the refraction coefficient is nearing to one.
Wave length and celerity decrease when the depth decrease but the wave period
remain constant.
Wave height decrease gradually while propagating away from the sailing line
and slightly increase near to the shore because of shoaling factor. Bigger waves
breaks at certain depth but smaller waves reach the shore without breaking. The
maximum wave height that reaches the shore is 0.112 m, which is very small
compare to wind wave. Wind generates 1.2 m to 1.7 m of wave at Tanjung Piai.
Bigger waves produce higher energy to the beach and energy correlated
exponentially to wave height. Highest energy at the beach produced by wind wave is
58000 kJ/m. Highest energy from ship waves is 250 kJ/m and this value is very
small compare to energy from wind wave. From the result of this study, based on the
energy formation to the beach, ship waves does not contribute to the erosion at
Tanjung Piai because ship waves produce smaller energy compare to wind waves.
5.2
Recommendations
Futher study on wave concentration to the beach could give better results.
Ship waves are more repetitive than wind wave and the total energy for the same
duration might not give the same value. This study only consider water level at
Mean Sea Level (MSL). The tidal change should be considered in future study to
improve the results especially the high tide condition. For various consideration of
ship waves analysis, numerical analysis is not suitable anymore because it require a
lot of calculation, data storage and retrieval. Thus, computer programming is
recommended.
68
The shape of the hull should be considered in ship wave generation, further study
using software like Michlet, Ship Wave Pattern Evaluation (SWPE) or Shipflow and
collaboration with marine engineers would give better result because the
understanding of the ships is important.
69
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