Squat Effects of Very Large Container Ships with Drift in a Harbor Environment

Date Author

Address

September 2007 H.). de Konlng Gans

Deift University of Technology Ship Hydromechanics Laboratory

Mekelweg 2, 26282 CD Delft

TUDeift

DelftUnlverslty of Technology

Squat Effects of: Very Large Çontainer

Ships with Drift in a Harbor Environment

by

Dr.ir. HJ. de Koning Gans

Report No. 1541-P 2007

Presented at the International Maritime-Port Techno-logy Conference, MTEC2007, Sept. 26-28, 2007, Singapore, ISBN: 978-981-05-8949-3, 'PublIshed by: Research Publishing Services, Singapore

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2

International Advisory Panel

BG(NS) Tay Lim Heng

Chief Executive, Maritime

_{and Port Authority of Singapore, Singapore}

Mi. Pieter Struijs

Senior Executive Vice-President, Port of

_{Rotterdam, The Netherlands}

Mr. Khiatarii Manohar

_Ramesh

Assistant Managing Director, Cluster Group 1,

_{Economic Development Board,}

Singapore

Mr. Peter Kneipp

President and CEO, MTU Asia Pte Ltd, Singapore

Mr. John Stansfeld

Director for Asia, Lloyd's Register Asia, Hong

_Kong

Prof. Wang Zuwen

President, Dalian Maritime

_{University, China}

Mr. Ki-Daj Yum

President, Korea Ocean Research and Development

_{Institute, South Korea}

Mr. E. Van den Eede

President, PIANC, Belgium

Mr. H. Thomas Kornegay

Executive Director, Port of Houston Authority, USA;

Immediate Past President,

_{International Association}

Mr. Toh Ah CheOng (Chairman)

Director, Technology Division, Maritime and Port Authority of Singapore,

Singapore

Prof. Chan Eng Soon (Co-Chairman)

Head, Department of Civil Engineering, National University of Singapore,

Singapore

Mr. Loh Chee Kit

Deputy Director (Engineering)/Project Director (PFF), Technology Division,

Maritime and Port Authority of Singapore, Singapore

Dii

Mr. Goh Kwong Heng

Deputy Director (Research & Technology) / ClO, Technology Division,

Maritime and Port Authority of Singapore, Singapore

_Pr

Fa

A/Prof. Choo Yoo Sang

_De

Director (Research), Centre forOffshore Research & Engineering,

Faculty of Engineering, National University of Singapore, Singapore

Pr

Fac

AIFrof. Edmond Lo Yat Man

He

Head, Division of Environmental and Water Resources Engineering,

Th

Nanyang Technological University,, Singapore

A/Prof. Tan Soon Keat

Dii

Director, Maritime Research Centre, Nanyang Technological University, Singapçre

Thi

ore

Technical.. Committee

A/Prof. Choo Yoo Sang (Chairman)

Director (Research), Centre for Offshore Research & Engineering, Faculty of

Engineering,. National University ofSingapore, Singapore

A/Prof. Tan Soon Keat

Director, Maritime Research Centre, Nanyang

_{Technological University,}

Singapore

A/Prof. Tiedo Vellinga

Faculty of Civil Engineering and Geosciences,

_{Ports and Environment,}

Deift University of Technology;

Director, Environment,

Safety and Spatial Planning, Project Organisatioñ

_{Maasvlakte 2,}

Port of Rotterdam, The Netherlands

Prof. H. Ligteringen Msc

Faculty of Civil Engineering and Geosciences,

_{Chair, Ports and Waterways,}

Delft University of Technology, The

Netherlands

Prof. Dr. M.P.0 Weijnen

Faculty Technology, Policy and Management,

Head Infrastructure Systems and Services,

_{Deift University of Technology,}

The Netherlands

Mr. P.W. Mollema Msc

Director, Strategy Port Infrastructure and

_{Maritime Affairs, Port of Rotterdam,}

The Netherlands

Dr. Pave! Tkalich

Senior Research Fellow, Deputy Head,

Physical Oceanography Research

_{Labaoratory, Tropical Marine Science Institute,}

vi

Technical Committee

Prof. Wang Chien Ming

Structural and Offshore Engineering Group, Department of Civil Ertgineering,

National University of Singapore, Singapore

Prof. Soh Chee Kiong

Division of Structures and Mechanics,

Schoöl òf Civil & Environmental Engineering, Nanyang Technological Universi;

Singapore

A/Prof. Hsu Wen Jing

Deputy Director, Maritime Research Centre, Nanyang Technological University,

Singapore

Dr. Song Tiancheng

Assistant Director (Engineering and Planning),

Maritime and Port Authority of Singapore, Singapore

Mr. Teo Chee Beng

r

Assistant Director (Electronics and Communications),

Maritime and Port Authority of Singapore1 Singapore

Mr. Parry Oei Soe Ling

Chief Hydrographer, Maritime and Port Authority of Singapore, Singapore

Capt Lee Cheng Wee

Deputy Director (Port)/Deputy Port Master,

Maritime and Port Authority of Singapore, Singapore

International Advisoiy Panel

Organizing Committee

Technical Committee

PORT PLANNING, DEVELOPMENT AND OPERATIONS

Port Research and Development in China

_[Keynote]

Wang Zuwen and Lu fing

A New Full-MissIon Tug Silmulator SystemRequest for Realism

and Accuracy

Peter Kr. Sorensen

A Quay-Length-Based Berth Allocation Strategy Using Heuristic

17

Algorithm and Simulation Optimization

Wei Yan, Weijian Mi, Daofang Chang and Hongxiang Wang

A Simulation Study on the Docking Station Concep.t in the

24

Container Yard

Loo Hay Lee, Bk Peng Chew, Kok Choon Tan, Qian Wang and Yongbin Han

Agent Based Risk Management & Operational Modelling of Ports

30 R. D.. Coiwill and S. L. Yeung

An investigation into Yard Crane Scheduling Based

36

on Dynamic Deployment and Hill-Climbing Algorithm

Weijian Mi, Wei Yan, Daófang Chang and junhiang He

Constniction of the Deurganckdok in the Port of Antwerp, Belgium.

43

Manu Vandamme, Grèet Bernaers and Freddy Aerts

Corrosion Aspects in the Pört of Rotterdam

₄₉

A. van der Toorn, Frank Leatemia, Piet Jon gbloed, Paul de Beijer

and Piet Louwen

vü

The Development of Floating Terminals and Transshippers in Aia

5ó

Chung Olee Kit

iv

V

Contents

St]

R.

Integrated Solutions for Port- and Supply 'Chain Security

_{106 Su}

Werner Krüdewagen

- Se

Maasvlakte 2: ASustainable Expansion of the Port of Rotterdam

113 B.

Tiedo Vellinga and Paul van Eijk

Model of Optimizing Ship Stowage Planning at a Container Port

120

Nguyen Thanh Thuy and Akio 1mai

-More infrastructure Capacity Per Acre? Methodology

_{to Establish the}

₁₂₇

(im)Possibffities of Combination of Infrastructures

-

Cl

G P J Dzjkema, I Nikohc, S Biesheuvel, S Ijsselstzjn, J Baggen, J Stoop,

O. van de Riet, H. A. Weustenenk and J. Smits

Planning for Inter-Terminal Container Transport

₁₃₃ -

01

Shell Ying Huang, Wen Jing Hsu and Rui lie Heng

G.

Planning of Ferry Terminai Operations Through Simulation

₁₃₉ A1

Jayanta Majumder, Dracos Vassalos, Shikha Sarkar, Hyun Seok Kim,

Th

Dimit ris Konovessis, Luis Guarin, Anthony York, Terje Dahi berg

an

and Jonathan Logan

_A

Port of Sohar Developthent-Successes and Lessons Learnt

T 146 Lu

Jamal T. Aziz

_Cc

Preventing Time Overruns in Port Modernization Projects: Improved

152 Ei,

Design Approach

_D

Pranshu Jam, Koshy Varghese and B. Sanjeev Kumar

_Lo

Floating Cranes: Fast, Fresert and Possible Future Developments in 'Bulk

63

and Container Handling

-B, A. Pielage and J. C. Rijsenbrij

Future ShortSea Container .Terrninals Concept Development and

70

Evaluation Methods

J. C. Rijsenbrij and B. A. Pielage

Future Trends in Quay Wall Design

₇₇

J. G. de Gijt and A. van der Toorn

Hydro Jets of Fast Ferries Require Proper Designed Quay Walls

₈₄

Henk J. Verheij and Chris Stoiker

The Influence of the Environment iii Brown and Green Field

₉₁

Port Planning at the Port öf Rotterdam

C. (Cleo) Hupke-Lenger and J. (Joop) Smits

Innovative Quay Structures at the Port of Eemshaven, Eemsrnond,

98

OFFSHORE AND MARINE ENGINEERING

Climate ChangeChallenges and Possibilities for Sea Transport in

223

Arctic areas

_[Keynote]

Egil Rensvik

Offshore Oil & Gas

- Impact on Technology

_[Keynote]

₂₂₈

G. J. van Luijk

Approaches to Dynamic Mooring Analysis

₂₂₉

Thomas M. Foster, Stephanie Doorn-Groen, Zhang Xiaoli

and Mark A. Oliver

Assessment of Fracture Strength of Cracked Offshore Tubular Joints

235

Lie Seng Tjhen and Yang Zhengmao

Corrosion Protection Management for Floating Structures

241

Eiichi Watanabe

Design and Development offhe Marma South Pier (MannWorks

Loh Yan Î-lui, Seah Kim Huah, Sam Tan and Lim Soo Kim

215

Revaluation of Concrete Design in Marine Engineering

159

J. Overbeek and A. Q C. van der Horst

Risk Assessment: Singapore LNG Termir al Operation

165

Kelvin Lee Hui Kiat and Dimitris Konovessis

The Role of Ports in Global Supp1r Chains

172

Albert W. Venstra

Routhg and Scheu1ing of Parcel Tankers: State of the Art

180

and Opportunities

Hon g-Choon Oh and I. A. Karinii

Service Network Planning System for Liner Shipping

187

Ratih Dyah Kusurnastuti, Chuang Min-Hsiang, Lam Soi Hoi

and Lam Siu Lee

Simulation Study Lock Complex Ijmuiden

194

98

R. Groenveld and M. Pluijm

Strategies for the Development of Sustainable Ports

201

R. M. Stikkelman, G. P. J. Dijkema and P M. Herder

1:06

_{Supply Chain Managernent A Driving FOrce Towards the Trarsition}

_{to a}

₂₀₈

Serrated Growth Pattern in Global Container Fk)ws in. the Future?

113

B.Kuipers

Workload Forecating in a Container Terminal

120

Chen Chuanyu, Stuti Nautiyal and Ye Rong

Contents

Design Method and Some Examples of Fender System for PontoOn Type

254 Ri:

Floating Structures

Di

Shigeru Lleda, Takuyoshi Kurome1 Seigi Yamase and Motohiro Hineno

Dynamic Response Evaluations of Offshore Platform with

260 Se,

Reliability index

Z

Kenji Kawano, Yukinobu Kimura and Park Min-Su

Experin entai Fatigue Crack Growth of Steel Plates with a Single-Sided

267

-.

R

Composites Repair

Le

Hon gbo Liu, Xiao-Ling Zhao, Riadh Al-Mcihaidi and Chiew 'Sing Ping

Experimental Investigation of Free Spanning Submarine Pipeline Under

274 S.

Vortex-induced Vibration

s

Ong Yean Chau and Gho Wie Min

G

Experimental Studies on Fatigue Behavior of Partially Overlapped

280

Circular Hollow Section K-Joints

.

s

C. K. Lee, S. P. Chiew, S. T. Lie, T. Sopha and T. B. N. Nguyen

'

C(

Extension of Fatigue Life of Steel Flexural Members with. High-Strength

286

M

Composite Materials

. .:

S. P. Chiew and Y. Yu

Ci

Fatigue Performance of Fiber-Reinforced Lightweight

292

Ac.

Aggregate Concrete

_w

X. X.. Dai and J. Y. Richard Liew

.

St

HT-Direct Torque Motors Permanent Magnet Mòtors in Shipbuilding as

299 C

Direct Drive

Andreas Joeckel, Thomas Koch, Oliver Beck and Stephan Busse

Mi

interaction Between Sloshing Liquid, Container arid Moving Ship

306

:'

Is

Luong Van Hai1 K. K. Ang and C. M. Wang

Mesh Generation for Partially Overlapped Circular Hollow Section

313

A

K-Joints Under Fatigue Loadings

Tr

S. P. Chiew, C. K. Lee, S. T. Lie, T. B. N. Nguyen and T. Sopha

Ji

an

Numerical and Experimental Studies of Sloshing Waves in

319

Rectangular Tanks

..

A

M. M. Gao, C. G. Koh, W. H. ¡Juan and C. Luo

. . . G

Numerical Evaluation of Roll Damping Acting on a Floating Body Using

326

A

Navier-Stokes Solver

M

Tomoaki Utsunomiya and Hiroshi Ogura

A

Optimal Layout of Gill Cells for Very Large Floating Structures

333 D.

Contents _xi

Risk-Based Design for Floating Offshore Structures

₃₄₀

Dracos Vassalos,, Dimitris Konovessis, Luis Guarin and Tan Kim Pong

Simulation cf Regular Waves and Their impact

_{on a}

₃₄₈

Semi-Submerged Cylinder

Z. Hao, T. B. Lim, X. K.. Wang and S. K. Tan

Simulation Technology for Offshore and

_{Marine Hydrodynamics Status}

₃₅₄

Review and Emerging Capabilities

Lee Sin g-Kwan and Seah Ah Kuan

Static Strength of Internal Ring Stiffened Tubular 'T' Joints

361

S. Nallayarasu and D. Pradeep Kumar

Stress Measurement in Offshoré Jac-Up Rig Using FiberBragg

367

Gratings Sensors

Khay Ming Tth, Chia Meng Tay, Swee Chuan

_{Tjin amid Chee Kiong Soh}

Structural Safety Assessment of Pontoon-Type VLFS in Waves

₃₇₃

Considering Damage to the Breakwater

Masahiko Fujikubo and Kazuhiro Yamamnura

Theoretical Investigation

_{on the Heave Response of a Floaiing Vertical}

₃₈₀

Circular Cylinder with Tuned Mass Damper

Adj Kurniawan and Gho Wie Min

Wave Induced Deflections and StressResultants

_{of Two-Floating Fuel}

₃₈₆

Storage System

C. D. Wang, Z. Y. Tay, C. M. Wang, K. W. Shah and T. C. Song

MARITIME ENVIRONMENT, NAVIGATION AND SECURITY

Issues of Green Ship and Roles of Engine

_Makers

_[Keynote]

₃₉₇

Peter Kneipp

A Compact Membrane Bioreactor System for

_{Integrated Wastewater}

₄₀₅

Treatment on Ships

jianfeng Li, Yaozhong Li, Fook-Sin Wong, Hwee Chuan Chua

and Fenglin Yang

A Safety-Driven Framework for Navigation

_{in Restricted Waterways}

₄₁₂

George Mermiris, Dimitris Konovessis, Dracos Vassalos and Tan Kim Pong

Automated Container Inspection Lanes for the Port of Rotterdam

. 418

Maurits van Schuylenburg, Henry Nugteren and Niels Dekker

Automatic Measurement of Diameter and

_{C&ncentratjon. of Marine}

: 425

Diesel Particulate Matter Using

_{Light ScaftêHiiMëthöd andFiltering}

Kartika Kus Hendratna, Fujita Hirotsugu,

_{Harano Wataru and Sukardi}

Contents

Ballast Water Treatment Using hO2 Nano-Structured Microsphere and

431 E

Nanofiber Membrane Photocatalytic Oxidation Reactor: A Case Study

E

and Future Application

_E

Pei Fung Lee, Xiwang Z hang, Alan J. Du, Darren Sun and lamés Leckie

Comparison of Data Sources fór Detçrmination of Design and

₄₃₈

Operational Wind and Wave Conditions

Thomas Lihrenholdt, Z hang Xiaoli and Thomas Michael Foster

The Detection of liihcit Oil Discharges from Shippmg & The Forensic

444

Analysis of Synthetic Aperture Radar (SAR) Imagery

Mark Womersley and Michael Buckley

Development and Demonstration of a Highly Cost-Effective

450

EIectrochemical Technology fór Ballast Water Treatment

K. G. Nadéeshani Nanayakkara, Yu-Ming Zheng, S huai- Wen Zou

and J. Paul Chen

Developments. in Maritime Focused Industrial Waite Treatment and

455

Management Using Cystal'lisahon Technology

Ji

Tang Tsen Meng., Hay Choon Teck, Toh Ah Cheong and Song Tiancheng

R

Dredging of Sand from a Creek, Adjacent to a Sànd-Spit for Reclamation:

463 . L

Its Impact on Spit Stability and Coastal Zone

. B

M. D. Kajago pal, P. Vethamony, L. Ilangovan, S. Jayakumar, K. Südheesh

. C

and K. S.. R. Murty

L

Dynamic System Simulation öf Passenger Eacu'ation in Large Passenger

470

Vessel During Tsunami Attack

Trika Pitana and Eiichi Kobayashi

. .

- P

Early Implementation of the e-Navigation and e-Maritime Concepts

477

Bohdan (Dan) Pillich

'.

The ECOPODE" Single Layer System for Coastal Protection

485

Michel Denechere, Michel Fons and Louis Sanchez

V

Electronic Port CIearanc&LMaking It Work for Small ànd

491

Medium Sized Ports

.

.

R

ørnulf Jan Rødseth, Jon Leon Ervik and Jane Hauge

. . L

Emission Reductions at Container Terminal Gates

498

G

Dimitnis Pacha kis R

Estimation of Carryiig Capacity of the Guiif of Kachchh, West Coast of

505 B

India in Relation .to Petroleum Hydrocarbon Through Oil Spill Modeling

' R

P Vet hamony, M. T. Babu, G. S. Reddy, K Sudheesh, E. Desa

..

477

485

491

Luis Guarin, Dracos Vassalos and Dimitris

_Konovessis

Contents _xiii

431

_{Evaluation of the Hartelkanaai Slope Protetions}

_{Test Site in the Port of}

512

Rotterdam, Case Study

j. Broos, A. A. Roubos and E. H. Van Ligten

Green Award Scheme, a Holistic Way to Address

Port + Marine

518

438

_{Environmental Concerns and Navigational Issues}

jan Fransen

444

_{of Technology in the Shipping Industry}

Harnessing Appropriate Legal Risk Management Practices in the Supply

525

Dennis Tan

1-WIS Absorption and Vapouf Suppression

₅₃₂

450

_{john S. Brinkinan}

Identifying Oil Pollution Sources and the Generation

_{of Source}

₅₄₀

Probabili:ty Maps

M. Kleissen

455

Innovations at the Car Yards; Beneficial Use ofa

_{Dumping Area}

₅₄₈

Riitta Kajatkari and Taru Halla

463

_{Leveragmg on WiMax to Enable Maritime}

_{Enterpnses to Accelerate}

555

Business Growth

Olivier Reins

LionGas LNG Terminai in Rotterdam Nautical and Societal QRA

561

470

_{H. Ligteringen, C. van der Tak, R. Dirkx and}

F. A. de Bóer

Mangrove Erosion Resulting from Ship Wake

₅₆₈

Pui Cuifen, Thomas Michael Foster, Amy Ling Chu Chu and Claus Pederson

Mapping. the Decision Landscape of Port Security Governance

₅₇₄

Mark Womersley and Michael Buckley

Microbiological Monitoring of Discharged Bllast Water

581

Volodymyr Ivanov

Real Time Monitoring of Dumping and

_{Dredging Activities in Singapore}

₅₈₅

Using Modern Marine Technology

Guoy Tong Kiat and Choy Kum Weng

xiv

Contents

Soft Soil Improvement for the Constrt.iction of an Ernbaikment on Very

606

Soft Sludge Deposits

Menge Patrick, Van Impe William and De Preter Hans

Squat Effects of Very Large Container Ships with Drift

613

in a Harbor Envirommert

H. j. de Koning Gans and H. Boonstra

Study of Tidal Current as a Tracer of the Phytoplankton .by MODIS

621

Shuzo Tanaka, Tsutomu Kanayama and TakiioYu garni

Surfing the IP Broadband Highway Across the Oceans The Business

626

Imperative for Reliable, Cost-Effective Broadband Connectivity in the

Maritime Industry

Tan Tian Sen g, Lee Foh Cheong and Chew Hup Boon

Tracking the Pulse of the Maritime Activities in Busy Harbour and Ports

634

Kum Chee Meng

Use of Dredged Clay 'Lumps as Fill Materials for Lad Reclamation

640

M. Karthikeyan, T. S. Tan1 W. S.0 hia and C. P. Tee

Using Water-Plate Collector on ESP 'to Reduce Marine Diesel

647

Exhaust Emission

I. Made Ariana, Fujita Hirotsugu, Nishida Osarni and Harano Wataru

Vessel Tracking - A Vision for the Future

655

lillian Carson-Jackson

Vessel Traffic Service of the Pbrt of Hong Kong

661

K. W. Fung and T. K. Cheung

-Author Index

' 667

SquatEffects of Very Large Còntainer Ships with Drift

in a Harbor Environment

H. J. de Koning Gans* and H. Boonstrat

Deift University of Technology, Mekelweg 2, 2628 CD Deift, The Netherlands

Squatis,a seriousproblem when very large container ships areentering harbors with small underkeelmargins. The squat effects are that theship acquires sinkage and trim. Due tothis sinkage and trim the keelclearance decreases drastically. Thedistance betWeenbottom and ship becomes verysmall; and measures must be taken to avoid contact of the ship with the bottom Recently a study has been carned out by the University of Technology Delft In that study several methods have been used for ships sailing without a drift angle The results have been presentedat the'International Maritime-Port Technologyand development Conference 2005' inRotterdam.In that study only straight line coursesof ships,wlthout a drift angle, are investigated. But from model tests, it appears that when ships are sailing with a drift angle the squat effects have become much larger. To investigate the squat effects, due to drift, a program ha been set up to find the influence of the drift.

In the previous study a panel methods is used to predict the squat effects for sailing of ships without a drift angle. The panel method calculates a non-viscous flow exactly. The resultsshould be reliable, because theexactshapeof the ship hull is taken into account. The panel method is very convenient forsquatcalculations. For thesesquat calculations the free surface effects, which generates theso-called Kelvin wave pattern, don't have to be taken

into account. The influeiicéOfthese waves isvery small.

The tests havebeen carried out forlarge container ships (type Post Panamax ± 6500 lEU) toinvestigate thesquateffectsatdifferent driftangles. This researchwill deliver, hopefully, an indication whether the squat effects for (Ultra) Largecontainer ships are serious or not. Also, whenthejnjtjal keelclearanceis small,.the keel clearance in sailing condition becomes dangerously small and:it:isexpected the nonlinear effects, due to the drift, will have abig influence. The resultsof this. investigation will be compared to model tests to validate this method

1. Introductión

In this article the squat of very large container ships under drift condition is

investigated. In the previous study, presented at the 'International Maritime-Port

Technology and development Conference 2005, Rotterdam', a comprehensive investigation has been madeaboutsquateffects ofshipsailing inastraight course.

The former research only presents the squat 'phenomena in straight line course. But already mentioned in Ref. 8 it will be expected that the squat effects become

614 _{H. J. de Koning Gans nñd H. Boonstra}

larger when the ship sails in drift condition. First of all the blockage will increase.

Through this the return velocity _{of will increase, because the same amount of} water has to flow through _{a smaller gap. According to the Bernouilli equation}

the pressure will decrease and the water level as well as the ship will go dOwn. Secondly, under drift conditións a much larger gap under the ship occurs, where the water 'has to flow from one board to the other. Because the gap under the keel is small and the water velocity under the ship keel will (probably) have a higher velocity an extra suction force will occur; Thirdly, the drifting ship looks like a lifting device. So at one board the velocity will increase, while at the other board the velocity will decrease. So at one board a higher pressure zone and at the other a lower pressure zone will occur. So_{an etra flow will be generated due to this}

pressure gradient and will also flow under the_{ship kill and using the Bernouilli}

equation the pressure will decrease again' and' will do sink ship extra.

To calculate the squat effects of a drifting a three dimensional panel method _is used, which can also calculate lift-effects. _{At the aft end of the ship a dipole (or} vortex) layeris placed, which describes the trailing vortices; By this technique the influencesof vortices can bedetermined and lifting, effects can be determined.

The presented research has only been carried out for a post panamax container ship and at only one water depth.

2. Panel Methods, the Three Dimensional Method

In the last part of the previous century numerical methods have been developed to calculate the potential flow, with _{or without wave pattern around ship hulls;} The advantage of numerical methods is that the velocities and pressures can be

calculated at each point of the wetted surface of the ship hull as well as at the

free surface. Also the forces and moments can be determined by integrating the

pressure with respect to the wetted hull. Só more and new insights concerning the behavior of the flow can be analyzed. The tests can be carried out with or without free surfaces effects. When the geometry or flow direction is changed

a quick calculation can be made in order

_{to gain more insight regarding the}

characteristics of the flow. Atthe TUDeift a numerical method based program: was developed. This program is based on a panel method using a Dirichiet boundary condition; Thepanelsare placed on the wetted hull surface and on the free surface around the ship; The program can predict the double body flow when panels are only placed on the wetted hull.

2.1. Adaptation of the panel method for_{shallow water}

The panel method describes that the sinkage is'corisists:of a Froûde depth number

dependent part and a geometrical or shape of the ship hull. So the squat _can

be calculated' according to S = f(F11)g(Geom). So for the linear squat calculations

using a panel method the same principle is used. When only the panel 'method

Squat Effects of Very Large Container Ships with Drift ma Harbor Environment ₆₁₅

where the hull and the bottom are mirrored in the free surface. The calculated pressures are proportional to the square of the velocity. From this the forces moments, sinkage and trim are also proportional to the square of the velocity

p,F, M,s, t y2 _{Ft., But by using the panel method the shallow water equation}

is not built in. Tuck has derived _{that. for shallow water problems the pOtential} equation has to fulfill the shallow water hydrodynamics. So from the shallow

water hydrodynamics equation the calculated pressures, forces and moments are proportional to p, F, M, s,.t _{F1/ /(1' - F,.). So, the results of the panel method} has to be corrected with the the shallow water equation and this is Froude depth number dependent:

p, F, M,.s, t cx h ₍₁₎

3.. The Squat 'Results of the Linear Panel Methods 3.1. Theditnensjon of the container vessel

The calculationshave beencarried out fOr one container ship andatone canatdepth. The type of container ship is the so called the 'Post Panamax'. The canal depth is relative to container ship and isand 2.O,m_{deeper than thedraughtofmecontainer} ship. So, the initial keelclearance (this is the keel clearance when the ship _{is in rest)} is 2.Om. Thedimensions and the specific ship parameters areshown in Table 1. 3.2. The test program

The test program has been carried out oía post panamax container ship sailing_at the center of the canal with a width of 300 rn depth of 16m. The keel clearancefor all situationsis2 m A variation has been_{madeof:thecoursepath incross direction} and of the drift angles. The reference of the ship is defined at amidships and the course path is along the fictive line which is described bythe amidships reference.

Table 1. _{Dimensionsand specific parameters of the tested container ship.}

Dim. _{Post Panamax}

[TEU] 6500 [ml _318.0 Fm] _302.0 [ml 42.9 Fmi 24.1' [ml 140 [m3J ₁₂₁₉₈₉ FJ o;6726 F] 6.089 [ml[%J _4.50(=r 1.36) Fn,2] 10393 F J _0.8022 Fm] F%l

-

_{14.17 (= 4.69)} Parameter Container Cap. Length:o.a.L0 Lengthcp.p. Le,, Breadth B DepthH Draught T Displacement V Block coef.c, Slendernesscoef. A =

616 _H.

1.4e Koning Gans and H. Boons tra

w

Fig. 1. _{Theinitia1 conditons of determine thesquat efifects.}

The course linesare at thecenter_{and 20m asideof the centerofthecanal.}

The drift angles are'respectively 0°, ±7.5° and ±159. The drift angle will be defined positive, when the bow of the.ship isat the port side of the course line. The calculations are carried out with and without a wake surfacebehind the ship. In fact when there is no wakesurfacebehind the ship, the lifting effectsare neglected. On the otherside when the wake surface and model are implemented, the full lifting effect is taken into account. The velocityof the_{container ship is set to the unity velocity 1 rn/s. The} velocity has to bechosenonce. By applying the Bernouilli equation the pressure is quadratic with the velocity and therefore the forcesarequadratic with the velocity of the ship. Of course the shallow water equatión can be adapted. Note that_from symmetry some test runs givesthesame answer as the symmetrical_{case. (so F(dy =}

x, b = y) = F(dy = x, b

_{= y)). The initial conditions are also presentedin Table}

1.

3.3. The sinkage force, trim moment, sinkage and trim

To predict the sinkage force, trim moment, sinkage and trim a panel method

is used. The panel method calculates an inviscous irrotational flow. So only the

inertial forces of the mass of the water are simulated. From the panel method

calculations, it appears that the sinking force and the trimming moment become

greater when the drift angle is greater. This means that the panel method gives a consistent result. The reliability of the results is more concerning. The _keel

clearances are very small and the_{panelsofthecanal bottom and the ship bottom} are very close to each other. Actually more panels and also smaller panels haveto

be used for proper calculations, but then the number of panels increases too much for a convenient calculation. (The number of matrix coefficients increases too and more floating points operations have to be doneon the same matrix components.

From this the truncation_{errors of the inversion process will occur and become}

greater). For some calculations some other grids have been distributed to obtain

the sensitivity of the panel distributión, It appears that the truncation error of

sinkage force is within 25% for every case. The truncation error of the trimming moments differs more and is about 10%. The momentsdjffer due to difficult flow around the bulb and around the stern at the location óf the propeller plane._These are areas where the distance to amidships is very large and have a large influence on the trimming moment. So for a proper calculation also a closer distribution of

Squat EffectsofVery Large Container Ships with Drift in a Harbor Environment 617 Table 2. Sinkage coefficient of the post panamax. This coefficient is a quadratic

polynomial coefficient.

titp5odp

Fig. 2. New situation when a ship. Fig. 3. Example of the pressure and velocity distribution

on the bottom and pressure distribution on the wetted

ship hull for the post pana max. The unit of the pressure is

Pa.

of how the flow is streaming around the bulbous bow is less interesting; only the force or pressure is of importance.

The results of calculations of the sinkages of the simulations are shown in Figs. 3 and 4. The trim is not presented, because from the calculations it appears that the trim angle is almost zero for all cases. The figures give the sinkage as functions

of the velocity (in knots). The first Fig. 3 shows the sinkages according to the formulation that the sinkage is only proportional to the square of the velocity or to the square of the Froude depth number. The last Fig. 4 shows the sinkage according to Eq. (29), in which the sinkage is corrected for the shallow water

theory and the predicted sinkage according to the linear theory.

Further a presentation is given in Fig. 3. This figure gives the pressure distribution

along the hull and bottom of the canal. Also the velocity distribution is given at the bottom of the canal. For the presentation of Fig. 5 the most important zone is zoomed in. From the figure, it can be seen that higher pressures occur at tile front zone and in the aft zones of the ship. In the middle of the ship (a) lower pressure zone(s) occur(s). Also it is good to see that there occur cross flow components. These cross flow components already occur when the ship is sailing without drift. From this viewpoint it is expected that the cross flow will increase (drastically) when the ship sails in drift condition.

4. Results

The results of the sinkage are presented in Figs. 4 and 5. The results of the trim

are not presented, because after the calculations it appears that the trim is very

Test run Drift angle

Off set center canal 15° 7.5° 0° 7.5° 15°

20m

0.023 0.0088 0.0044 0.0077 0.021

0m 0.018 0.0081 0.0044 0.0081 0.018

618 _{H. J.de Koning'Gans'and H. Boonstra} 02 0.3 05 06 f.?0.80.9 0.0 0,8 O.. 1.1 1,2 1.3 t3 t 00

Smug, al-20m allaIt 0f c.ntnr O.n.0

(prepoOlanal to 8500W of velocity)

beta. -IV bete. 7.1 bat.. IS'

velocity (ttnotej"

SInk.g. 01.20 flt 01100101 cent., canal (oncoming to ahInco Water equation)

btto.-10 bato -7.0' boto.0 baIa.7.t' bat. IS. nelocIty (knntoj

'Fig. 4. _{Sinkage propotional tothe squareoí the velocity.}

Slob.g, at cente, canal (.ccordbng to shallow water equation)

bOlaa.tt'

bato e-7V

-- bnt..V

Fig. 5. Sinkage according to the shallow water equation.

small for these cases. Of course for symmetrical reasons the sinkage is the same for the offset to portside and starboard, when the drift angle is 'opposite. From the sinkage can be calculated according the following equation:

s = c5v2

In which the velocity is expréssed in (m/s).When the shallow water equation is

used the sinkage can be calculated with the same coefficient: The sinkage according to the shallow water equation is:

SCV/

Note that in this equation also the velocity of the ship is expressed in (rn/s.). 4.1. Discussion of the results from' the panel method

The resultsof calculationsof thepanel' method arëin accordance with the expected

smkage. The real sinkage will differ with reality, because in reality viscosity is present. This viscosity will cause that vortices occur at places, which is not

implemented in the panel method, Only at the aft end of the-ship a wake is forced

0 tO IO

Squat Effects of Very Large Container Ships with Drift in a Harbor Environment 619

and all the vortices which will be occur, are concentrated in the trailing wake

surface behind the ship. Alsoit ispossible toput off the wake model and influence. So in this case only the inertia of the flow is taken into account.

From the results is also obvious that when the drift angle becomes greater the sinkage increases It is a nonlinear effect and it isclose to a quadratic effect:

s = s0 ± c2

Looking at this tendency, Figh drift angles have to be avoided, for two reasons.

First the pathwidth becomes very large and a meeting with another ship will

increase the change of collision. Second, the squat effects will be seriously and thechange of contact with the bottom increase drastically. So, this means that the squat effects become much larger when the drift angle is getting larger. In reality drift is not always avoidable, so this will be a big problem. In the simulated case thedrift is caused by wind and in reality this is hardly to avoid. By use of tugboats the drift can be controlled, because these boats can create a force by cables on the container ship.

5. Conclusions and Recommendations

5.1. Conclusions

Squat effects can be predicted by panel methods The calculations have to be

applied in the so-called double body flow, without panels at the free surface. Due to the small Froude number (based on the ship length) the wave phenomena play a very small role. This means panel methods can be applied for the squat effects and will give very accurate results.

From the research on the squat according to the (non) linear panel methods

some tendencies and conclusions are obtained. It appears that the panel method gives a consistent solution. When the drift angle becomes larger, then the squat

effects become larger. The panel methods with dipoles are more sophisticated

than only source based panel methods, because the lifting effects are taken into

account. However, when no wake model is deployed, the results of the panel method give almost the same results as the predictions with an implemented wake model. So, unfortunately the wake strength is not determined quite well.

The implemented wake model has to be adapted such that the wakestrength will fulfill the Kutta pressure condition. When the wake model is implemented well it will be expected that the present of vortices will magnify the squat effects.

From the literature, the prediction methods arecompared with tank results. The fact that the panel methods give less sinkage is most probably due to the lack of the presence of a boundary layer. Also truncation errors of the panel method can give small errors.

In full scale conditions the boundary layers are relatively less thick. So the influence on the squat due to the boundary layer is less than that according to

620 H. J. de KoningGans and H. Booñstra

5 2. Recommendations

The calculationsare carried out forone ship and at one depth. Toget more insight

in the squat phenomena, more tests have to be carried out for several container

ships at several initial keel clearances.

TO validate the results of the panel method, model tests have to be carried out. Now the results of panel method can be compared with the results of the model tests. Attention has to be paid on the present of wake model.

A larger test program has to be researched. In this research the maximum off set of the course line is only 20m. In reality theoff set can be much more and therefore it has to be iñvestigated too.

The research can also be extended for inlandships. The natural environment of these ships is restricted andconfined waters andcanals. The squat effectsof inland ships are seriously and with a new research more knowledge can be obtained References

1. Barrass1 CB. "ShipSquat - A Reply", The Naval Architect, November 1981.

2 Flugge G & Uhczka K Fahrverhalten grosser Con tainerschiffe in extrem flachem Wasser

Das dynamische Fahrverhalten und die Wechselwirkungen mit der Fahrrinennsohle von

sehr grossen Containershiffen unter extremen Flachwasser-bedingun gen",

Hansa-Schiffahrt-Schiffbau-Hafen-138. Jahrgang-2001-Nr 12.

Koning Gans, H.J. de, "Squat Effects of Very Large Container Ships Sailing in a Harbor Environment", Report No. 1407-O, Laboratory of Ship Hydromechanics, TUDe1fL (Dëlft University of Technology) and Port Research centre Rotterdam-Deift PubI., November

2004, Delft, ISBN 90-5638-134-2.

Koning Gans, H.J. de, "Squat Results from Calculationsof Panel Methods",

ReportNo.1408-O, Laboratory of Ship Hydromechanics, TU Delft (Deift University of Technology) and Port Research centre Rotterdam-Deift Publications, November 2004, Delf t, ISBN

90-5638-135-0.

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environment", 'International Maritime-Port Technology and development Conference

2005, Rot-terdam, September 2005 Rotterdam ISBN 90 80989 21 5 (old) ISBN 978 90

80989-21-4 (neW).

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Bulletin Nr. 95, Bonn 1997.

Schuster,S., "Untersuchingen über Strömungs-und Widerstand-verhältnisse bei der Fahrt van Schiffen in beschränktem Wasser".

8 Schmiechen M Squat Formeln Das Schiff' in begrenzten Gewassern 18 Duisburger

KollòquiümSchiffstechnik/Meerestechnik, Duisburg, 1997.

9. Uliczka,.K., "Das Schiff ïn Wechselwirkung mit der Wasserstrasse(TheShipinInteractionwith

the Waterway)", Verkehrswasserbau an Seeschifffahrtsstrassen (Hydraulic engineering