Strength and Hydrodynamic Performance of a Multihull Vessel Musa Bello Bashir Submitted for the degree of Doctor of Philosophy February 2014 School of Marine Science and Technology Newcastle University United Kingdom Acknowledgements I would like to express my appreciation to my supervisory team which comprised of Professor Mehmet Atlar, Professor Robert – for being my tutors for the past seven years and Professor Longbin Tao. I am deeply indebted to them for their continued assistance and the mentoring that I have enjoyed from them in the last four years. It has been really a great privilege to have worked under your supervision. I am very grateful to Dr Jonathan Downes and Dr Simon Benson for their assistance on the use of the MAESTRO Program (FEA and Hydrodynamic). I am also grateful to Dr Andrew Smith; Mr Peter Bowes – for pressing the “Green Button”; Mr Robert (Bob) Hindhaugh; Mr Jerry Lambert and Mr Liam Rogerson – for their assistance during the towing tank tests measurement. Special thanks are due to Mr Olgun Hizir for his timely assistance and some collaborative work on the seakeeping validation of this thesis by using the PRECAL program, with the kind permission from Lloyds Register (LR). I would also like to thank Mr. John F Garside for his invaluable assistance on this work over the last three years. I am also grateful to Professor B Okan; Dr K C Seo; Mr Richard Carter. Miss Victoria Coulson, Ms Carol Bennett and Mrs Sue Vecsey - for the support I enjoyed from them over these years. I am really greatly indebted to friends and fellow research students whose company I so much enjoyed. I am thankful to Danyal Fard, Nicola Everitt, Hani Al-Hababi, Muhammed Zoolkfakar, Anuar Abu-Bakr, Alfred Emmanuel, Bello Imam, Ali Reza, Hussein Enshaei, Stavros Karamedis, Maryam Haroutunia, David Trodden, Jaime Torres-Lopez, Maria Syrigou, Serena Lim, Ikuobase Emovon, Serkan Turmen, and Batuhan Aktas, I am particularly grateful to Sadiq Lamuwa, Mohammed Mahmud (Graduate), Andriy Wiepandy Ng, Dr Sani Yahaya, Dr. (Cdr) KD Shittu, Dr Umaru M. Ba, Dr Achinike Ibekwe, Dr Aminu Bayawa, Waziri Galadima, Mr Ronye Egborge, Mr Emeka Oti, Sani G. Ibraheem, Sani Shira, Stephen Are, Craig Porter and Norman Craik for their encouragements. I would also express my sincere appreciation to Col MU Wambai for being there for me at all the times. Lastly, I am grateful to my mum and dad for their love, support and endless patience, my brother and sisters, cousins, nieces and all the people of goodwill - for their support and encouragements. I am particularly grateful to my wife, Fatima, and the kids, Asmat and Alman, for having to endure my absence throughout the duration of my study. i Abstract The use of catamarans as an alternative to more conventional monohull high speed vessels for transport, naval and offshore applications is on the increase. This uprising trend is a direct consequence of the global demand for commercially and militarily efficient vessels that offer high speed, potential for improved Seakeeping at speed, relatively low hydrodynamic resistance in waves and a more useable deck area. The configuration and hull geometry of catamarans are very critical to achieve improved seakeeping and other hydrodynamic performances. The Round Bilge hull form is one of the most prominent hull geometries in use for the design of displacement-type multi-hull vessels. An alternative hullform series to the Round Bilge, catamarans, named the Deep-V Catamaran series (DVC), has been developed recently at Newcastle University. Early studies on the DVC concept based on this series indicate that the hull form may have better resistance performance than the Round Bilge. However, other important characteristics of this concept such as the motions and wave-induced load response characteristics are still unknown. There is also a lack of understanding of the general hydrodynamic characteristics of the DVC concept in comparison to the Round Bilge hull form. This study contributes to the understanding of the motions and wave induced load response characteristics of the DVC concept. It is also intended to advance the structural design methodology of the DVC concept and its subsequent application as better alternative to the Round Bilge hull form. The study involved the experimental and numerical investigations of the motions and wave- induced load response characteristics of the DVC concept by using a prototype model of “The Princess Royal” which is the current research vessel of Newcastle University. The experimental studies involved the motions and wave-induced response measurements in regular waves at both zero and forward speed conditions. The results obtained were validated using alternative potential flow-based numerical codes in frequency domain. The benchmark study indicates that the numerical codes are capable of producing acceptable results. A comparative study using a representative model of the Round Bilge hull form with the DVC model was conducted in order to establish a direct basis for the comparison of the motion and hydrodynamic load performances. The results obtained from this comparison reveal that the DVC may have better seakeeping characteristics and is less sensitive to wave loads than the Round Bilge hull concept in critical heading conditions. A further comparison of the experimentally validated numerical predicted loads with those obtained using the International Association of Classification Societies (IACS) approach was completed. The study confirms that the IACS approach over predicts the loads by up to 40% in Beam Seas and Quartering Seas when other components of IACS rules are not considered. A simplified structural analysis of the DVC model using the Finite Element Method was also completed to demonstrate the effects of the predicted loads on the strength of the hull structure with emphasis on the cross-deck structure, which is the most sensitive structural element of the vessel. Overall, the study highlights the promising characteristics of the DVC concept in comparison to the Round Bilge hull form and provides data required for the preliminary design of catamarans using this concept. ii Table of Contents Acknowledgements ..................................................................................................................... i Abstract ...................................................................................................................................... ii Table of Contents ..................................................................................................................... iii Table of Figures .................................................................................................................... viii List of Tables .......................................................................................................................... xvi Nomenclature ...................................................................................................................... xviii Abbreviation ............................................................................................................................. xx 1 Chapter One: Introduction ......................................................................................... 1 1.1 Introduction` ................................................................................................................... 1 1.2 Background and Motivation ........................................................................................... 1 1.3 Aims and Objectives ...................................................................................................... 7 1.4 Layout of Thesis ............................................................................................................. 7 1.5 Summary ........................................................................................................................ 9 2 Chapter Two: Background of Multihull Vessel and Literature Review ................. 9 2.1 Introduction .................................................................................................................... 9 2.2 Review of the Deep-V and the Round Bilge Catamaran Concepts .............................. 10 2.2.1 The Round Bilge Hull Form Concept .......................................................................... 10 2.2.2 The Deep-V Hull Form Concept .................................................................................. 12 2.3 Review of Motions and Wave-induced Loads on Catamaran ...................................... 15 2.4 Review of Structural Modelling and Design Considerations for Multihull Vessels .... 21 2.4.1 Considerations for Materials Behaviour ...................................................................... 22 2.4.2 The Structural Design Methodology ............................................................................ 24 2.5 Conclusions .................................................................................................................. 33 3 Chapter Three: Theoretical Background for Motions and Loads ........................ 34 3.1 Introduction .................................................................................................................. 34 3.2 Description of the Numerical Predictions Software ..................................................... 35 iii 3.2.1 The MAESTRO-Wave ................................................................................................. 35 3.2.2 The PRECAL ..............................................................................................................