DOCSLIB.ORG

Ship Stability

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ship Stability 2017-01-24 Lecture Note of Naval Architectural Calculation Ship Stability Ch. 1 Introduction to Ship Stability Spring 2016 Myung-Il Roh Department of Naval Architecture and Ocean Engineering Seoul National University 1 Naval Architectural Calculation, Spring 2016, Myung-Il Roh Contents Ch. 1 Introduction to Ship Stability Ch. 2 Review of Fluid Mechanics Ch. 3 Transverse Stability Due to Cargo Movement Ch. 4 Initial Transverse Stability Ch. 5 Initial Longitudinal Stability Ch. 6 Free Surface Effect Ch. 7 Inclining Test Ch. 8 Curves of Stability and Stability Criteria Ch. 9 Numerical Integration Method in Naval Architecture Ch. 10 Hydrostatic Values and Curves Ch. 11 Static Equilibrium State after Flooding Due to Damage Ch. 12 Deterministic Damage Stability Ch. 13 Probabilistic Damage Stability 2 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 1 2017-01-24 Ch. 1 Introduction to Ship Stability 1. Generals 2. Static Equilibrium 3. Restoring Moment and Restoring Arm 4. Ship Stability 5. Examples for Ship Stability 3 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 1. Generals 4 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 2 2017-01-24 How does a ship float? (1/3) The force that enables a ship to float “Buoyant Force” It is directed upward. It has a magnitude equal to the weight of the fluid which is displaced by the ship. Ship Ship Water tank Water 5 Naval Architectural Calculation, Spring 2016, Myung-Il Roh How does a ship float? (2/3) Archimedes’ Principle The magnitude of the buoyant force acting on a floating body in the fluid is equal to the weight of the fluid which is displaced by the floating body. The direction of the buoyant force is opposite to the gravitational force. Buoyant force of a floating body = the weight of the fluid which is displaced by the floating body (“Displacement”) Archimedes’ Principle Equilibrium State (“Floating Condition”) Buoyant force of the floating body W = -W = -gV = Weight of the floating body G Displacement = Weight G: Center of gravity B: Center of buoyancy B W: Weight, : Displacement : Density of fluid V: Submerged volume of the floating body (Displacement volume, ) 6 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 3 2017-01-24 How does a ship float? (3/3) Displacement() = Buoyant Force = Weight(W) L B T C T: Draft B CB: Block coefficient : Density of sea water W LWT DWT LWT: Lightweight DWT: Deadweight Weight = Ship weight (Lightweight) + Cargo weight(Deadweight) Ship Ship Water 7 Naval Architectural Calculation, Spring 2016, Myung-Il Roh What is “Stability”? FG G B Capsizing ℄ B1 FB FG FG Inclining W L WL(Heeling) 1 1 G G B B B1 Restoring FB ℄ ℄ FB Stability = Stable + Ability 8 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 4 2017-01-24 What is a “Hull form”? Hull form Outer shape of the hull that is streamlined in order to satisfy requirements of a ship owner such as a deadweight, ship speed, and so on Like a skin of human Hull form design Design task that designs the hull form Hull form of the VLCC(Very Large Crude oil Carrier) Wireframe model Surface model 9 Naval Architectural Calculation, Spring 2016, Myung-Il Roh What is a “Compartment”? Compartment Space to load cargos in the ship It is divided by a bulkhead which is a diaphragm or peritoneum of human. Compartment design (General arrangement design) Compartment modeling + Ship calculation Compartment modeling Design task that divides the interior parts of a hull form into a number of compartments Ship calculation (Naval architecture calculation) Design task that evaluates whether the ship satisfies the required cargo capacity by a ship owner and, at the same time, the international regulations related to stability, such as MARPOL and SOLAS, or not Compartment of the VLCC 10 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 5 2017-01-24 What is a “Hull structure”? Hull structure Frame of a ship comprising of a number of hull structural parts such as plates, stiffeners, brackets, and so on Like a skeleton of human Hull structural design Design task that determines the specifications of the hull structural parts such as the size, material, and so on Hull structure of the VLCC 11 Naval Architectural Calculation, Spring 2016, Myung-Il Roh Principal Characteristics (1/2) Loa W.L. W.L. B.L. B.L. A.P. Lbp F.P. Lwl LOA (Length Over All) [m]: Maximum Length of Ship LBP (Length Between Perpendiculars (A.P. ~ F.P.)) [m] A.P.: After perpendicular (normally, center line of the rudder stock) F.P.: Inter-section line between designed draft and fore side of the stem, which is perpendicular to the baseline Lf (Freeboard Length) [m]: Basis of freeboard assignment, damage stability calculation 96% of Lwl at 0.85D or Lbp at 0.85D, whichever is greater Rule Length (Scantling Length) [m]: Basis of structural design and equipment selection Intermediate one among (0.96 Lwl at Ts, 0.97 Lwl at Ts, Lbp at Ts) 12 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 6 2017-01-24 Definitions for the Length of a Ship Structures above main deck Main deck (Main) Hull Wetted line Molded line Length overall(LOA) Length on waterline(LWL) Stem tstem Design waterline Length between perpendiculars(L ) AP BP FP 13 Naval Architectural Calculation, Spring 2016, Myung-Il Roh Principal Characteristics (2/2) B (Breadth) [m]: Maximum breadth of the ship, measured amidships -Bmolded: excluding shell plate thickness -Bextreme: including shell plate thickness Air Draft D (Depth) [m]: Distance from the baseline to the deck side line -Dmolded: excluding keel plate thickness -Dextreme: including keel plate thickness Td (Designed Draft) [m]: Main operating draft Depth - In general, basis of ship’s deadweight and speed/power performance Draft Ts (Scantling Draft) [m]: Basis of structural design B.L. B.L. Breadth Air Draft [m]: Distance (height above waterline only or including operating draft) restricted by the port facilities, navigating route, etc. - Air draft from baseline to the top of the mast - Air draft from waterline to the top of the mast - Air draft from waterline to the top of hatch cover -… 14 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 7 2017-01-24 Definitions for the Breadth and Depth of a Ship 1/2 Molded breadth(B ) ,mld Deck plating Camber Deck beam Freeboard Scantling waterline Molded depth(D,mld) Scantling draft Centerline Dead rise CL Baseline Keel Sheer after Sheer forward Depth 15 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 2. Static Equilibrium 16 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 8 2017-01-24 Center Plane Before defining the coordinate system of a ship, we first introduce three planes, which are all standing perpendicular to each other. Generally, a ship is symmetrical about starboard and port. The first plane is the vertical longitudinal plane of symmetry, or center plane. 17 Naval Architectural Calculation, Spring 2016, Myung-Il Roh Base Plane The second plane is the horizontal plane, containing the bottom of the ship, which is called base plane. 18 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 9 2017-01-24 Midship Section Plane The third plane is the vertical transverse plane through the midship, which is called midship section plane. 19 Naval Architectural Calculation, Spring 2016, Myung-Il Roh Centerline in (a) Elevation view, (b) Plan view, and (c) Section view Centerline: Intersection curve between center plane and hull form Centerline Elevation view Plan view (a) ℄ (c) Section view ℄ ℄: Centerline (b) 20 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 10 2017-01-24 Baseline in (a) Elevation view, (b) Plan view, and (c) Section view Baseline: Intersection curve between base plane and hull form Elevation view BL BL Plan view (a) ℄ (c) Section view Baseline (b) 21 Naval Architectural Calculation, Spring 2016, Myung-Il Roh System of Coordinates zb zn yb O n-frame: Inertial frame xn yn zn or x y z E yn xb Point E: Origin of the inertial frame(n-frame) b-frame: Body fixed frame xb yb zb or x’ y’ z’ Point O: Origin of the body fixed frame(b-frame) xn 1) Body fixed coordinate system The right handed coordinate system with the axis called xb(or x’), yb(or y’), and zb(or z’) is fixed to the object. This coordinate system is called body fixed coordinate system or body fixed reference frame (b-frame). 2) Space fixed coordinate system The right handed coordinate system with the axis called xn(or x), yn(or y) and zn(or z) is fixed to the space. This coordinate system is called space fixed coordinate system or space fixed reference frame or inertial frame (n-frame). In general, a change in the position and orientation of the object is described with respect to the inertial frame. Moreover Newton’s 2nd law is only valid for the inertial frame. 22 Naval Architectural Calculation, Spring 2016, Myung-Il Roh 11 2017-01-24 System of Coordinates for a Ship Body fixed coordinate system (b-frame): Body fixed frame xb yb zb or x’ y’ z’ Space fixed coordinate system (n-frame): Inertial frame xn yn zn or x y z Stem, Bow zb zn zb SLWL yb yn xb x n BL yb AP LBP xb FP AP: aft perpendicular : midship FP: fore perpendicular LBP: length between perpendiculars. Stern BL: baseline (a) SLWL: summer load waterline (b) 23 Naval Architectural Calculation, Spring 2016, Myung-Il Roh K : keel Center of Buoyancy (B) LCB: longitudinal center of buoyancy LCG: longitudinal center of gravity VCB: vertical center of buoyancy VCG : vertical center of gravity and Center of Mass (G) TCB: transverse center of buoyancy TCG : transverse center of gravity z z Elevation view Section view y x x y G LCG VCG B G B LCB VCB K CL Plan view y z TCG z x G B G TCB LCB LCG B K CL ※ In the case that the shape of a ship is asymmetrical Center of buoyancy (B) with respect to the centerline.
Load more

Recommended publications
  • Conception and Evolution of the Probabilistic Methods for Ship Damage Stability and Flooding Risk Assessment
    Journal of Marine Science and Engineering Article Conception and Evolution of the Probabilistic Methods for Ship Damage Stability and Flooding Risk Assessment Dracos Vassalos * and M. P. Mujeeb-Ahmed Maritime Safety Research Centre (MSRC), Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, Glasgow G4 0LZ, UK; [email protected] * Correspondence: [email protected] Abstract: The paper provides a full description and explanation of the probabilistic method for ship damage stability assessment from its conception to date with focus on the probability of survival (s-factor), explaining pertinent assumptions and limitations and describing its evolution for specific application to passenger ships, using contemporary numerical and experimental tools and data. It also provides comparisons in results between statistical and direct approaches and makes recommendations on how these can be reconciled with better understanding of the implicit assumptions in the approach for use in ship design and operation. Evolution over the latter years to support pertinent regulatory developments relating to flooding risk (safety level) assessment as well as research in this direction with a focus on passenger ships, have created a new focus that combines all flooding hazards (collision, bottom and side groundings) to assess potential loss of life as a means of guiding further research and developments on damage stability for this ship type. The paper concludes by providing recommendations on the way forward for ship damage stability and Citation: Vassalos, D.; flooding risk assessment. Mujeeb-Ahmed, M.P. Conception and Evolution of the Probabilistic Keywords: ship damage stability; probabilistic methods; flooding risk Methods for Ship Damage Stability and Flooding Risk Assessment.
    [Show full text]
  • Miniscale Modelling of Gyroscopic Effect with Application to Sheep Steering
    IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 11, Issue 1 Ver. I (Jan. 2014), PP 47-56 www.iosrjournals.org Miniscale Modelling Of Gyroscopic Effect with Application to Sheep Steering. Prof.N.B.Totala1,Kanchan Rode2, Purushottam Shelke3 , MayurTope4, Vaibhav Mahadik5 1(Assistant professor, Department of Mechanical Engineering, MIT Academy of Engineering, Alandi (D), Pune, Maharashtra,412105) 2,3,4,5(Department of Mechanical Engineering,MIT Academy of Engineering, Alandi(D), Pune, Maharashtra,412105) Abstract: A gyroscope is a device for measuring or maintaining orientation, based on the principles of momentum. Mechanically, a gyroscope is a spinning wheel or disc in which the axle is free to assume any orientation. Although this orientation does not remain fixed, it changes in response to an external torque much less and in a different direction, than it would without the large angular momentum associated with the disc's high rate of spin and inertia. Ships or sea vessels require stabilization when they face heavy sea waves. A disturbing couple acts on the ships due to sea waves, hence stabilization of ship is necessary. Due to sea waves, ship will either roll or pitch. The amplitude of rolling is much higher than amplitude of pitching. The gyroscope can be used for reducing the amplitude of rolling and hence, stabilizing the ship. The fundamental requirement of gyroscopic stabilization is that, the gyroscopic must be made to precess by some external means (example: electric motor) in such a way that the relative gyroscopic couple exerted by the rotor should oppose any disturbing couple which may act on the ship.
    [Show full text]
  • Analysis of Active Gyro Based Roll-Stabilization of Slender Boat Hulls
    Analysis of Active Gyro Based Roll-Stabilization of Slender Boat Hulls Naval Architecture TAO ZHANG Master of Science Thesis Stockholm, Sweden 2014 Analysis of Active Gyro Based Roll-Stabilization of Slender Boat Hulls Tao Zhang [email protected] Academic Supervisor: Ivan Stenius Examiner: Jakob Kuttenkeuler Date: March 4, 2014 KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems Stockholm, Sweden 1 ABSTRACT Currently, traffic congestion often happens in big cities every day. People demand a new conceptual vehicle which has a slender shape to reduce space, lightweight structure to decrease the fuel consumption and innovative technology to adapt for multiple transportation conditions. NEWT is such a conceptual amphibious vehicle that satisfies people's requirements. However, everything has two sides. Slender shape and high centre of gravity will result in instability. When NEWT runs in low speed, it easily gets rolled over. In order to make up for its drawback, gyro-stabilizer has been applied to the vehicle. By tilting the rotational gyro, it generates a counter torque counteracting the roll motion to make the vehicle recover to an upright position. Therefore this master thesis analyses the original stability of the vehicle and the possible improvement by adding the gyro system for both land and water-conditions. The model can handle the problem that the vehicle meets periodic disturbance forces, such as wave excitation force and wind force. 2 FOREWORD First I really appreciate my supervisor Ivan Stenius for his help. His constant feedback, comments, discussion, and encouragement always enlighten me and show me the right way. I would also like to acknowledge my teachers: Jakob Kuttenkeuler, Anders Rosén, Karl Garme, and Stefan Hallström.
    [Show full text]
  • Intact Stability Criteria for Naval Ships Apr 2 9 1997
    INTACT STABILITY CRITERIA FOR NAVAL SHIPS by Fred6ric Deybach Engineer Degree in Naval Architecture Ecole Nationale Superieure des Ing6nieurs des Etudes et Techniques d'Armement, 1992 SUBMITTED TO THE DEPARTMENT OF OCEAN ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN NAVAL ARCHITECTURE AND MARINE ENGINEERING AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY FEBRUARY 1997 © 1997 Fred6ric Deybach. All rights reserved. The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part. Signature of Author .. ....................................... Department of Ocean Engineering -. - January 17, 1997 Certified by ............. ..,.. .. .... ......... .... ................. ............... Alan J. Brown, Professor of Naval Architecture Thesis Supervisor, Department of Ocean Engineering A ccepted by .............. ............................... ., J. Kim Vandiver, Professor of Ocean Engineering Chdifrim, Qcean-.Mineering Departmental Graduate Committee APR 2 9 1997 iLBRARIES INTACT STABILITY CRITERIA FOR NAVAL SHIPS by Fr6ddric Deybach Submitted to the Department of Ocean Engineering on January 15, 1997 in Partial Fulfillment of the Requirements for the Degree of Master of Science in Naval Architecture and Marine Engineering ABSTRACT The United States Navy uses an intact stability criteria that was developed during World War II. This criteria is empirical and does not consider ship characteristics other than the righting arm curve. It does not directly consider the Sea State or the wind gusts. The International Maritime Organization is using a criteria developed in the 1970's and 1980's. This criteria is also empirical, and does not directly consider the Sea State. In this thesis the fundamentals of both the US Navy and IMO criteria are discussed.
    [Show full text]
  • UNSTABLE SHIP MOTIONS APLIED on SHIP-WEATHER ROUTING ALGORITHM Simroutev2
    UNSTABLE SHIP MOTIONS APLIED ON SHIP-WEATHER ROUTING ALGORITHM SIMROUTEv2 Bachelor’s Thesis by Lluís Basiana Ribera B.Sc A thesis submitted in fulfilment of the requirements for the degree of Nautical Science and Maritime Transport Department of Nautical Sciences and Engineering Facultat de Nàutica de Barcelona Universitat Politècnica de Catalunya Barcelona Submitted May 2018 Abstract Some combinations of wave length and wave height under certain operational conditions may lead to dangerous unstable motions for ships in accordance with the IS Code. The susceptibility of a ship to dangerous phenomenon will depend on the stability parameters, ship speed, hull shape and ship size. This signifies that the vulnerability to dangerous responses, including capsizing, and its probability of occurrence in a singular sea state may differ for each ship. During navigation periods these unstable motions are able to be encountered, which may lead to a cargo or equipment damage and the unsafety of the persons on board. The main reason for these causes is rarely known and currently there are just few work such as the International Maritime Organization guidelines which tries to ensure adequate dynamic stability (IMO, MSC.1/Circ.1228, 2007). Ship routing systems are gaining importance in the maritime sector as the use of these systems can lead to the reduction of fuel usage and reduce costs. Therefore, a mitigation of carbon emissions and improvement of maritime safety happens due to the avoidance of bad weather conditions. The implementation of pathfinding algorithms to determine the optimal ship routing has been widely used for transoceanic distances. However, the evaluation of short distance routes with ship-weather routing algorithms is still scarce, due to the low spatial resolution of wave fields.
    [Show full text]
  • 01-NAC-Introduction to Ship Stability(171229)-Student.Pdf
    2018-08-07 Lecture Note of Naval Architectural Calculation Ship Stability Ch. 1 Introduction to Ship Stability Spring 2018 Myung-Il Roh Department of Naval Architecture and Ocean Engineering Seoul National University 1 Naval Architectural Calculation, Spring 2018, Myung-Il Roh Contents þ Ch. 1 Introduction to Ship Stability þ Ch. 2 Review of Fluid Mechanics þ Ch. 3 Transverse Stability Due to Cargo Movement þ Ch. 4 Initial Transverse Stability þ Ch. 5 Initial Longitudinal Stability þ Ch. 6 Free Surface Effect þ Ch. 7 Inclining Test þ Ch. 8 Curves of Stability and Stability Criteria þ Ch. 9 Numerical Integration Method in Naval Architecture þ Ch. 10 Hydrostatic Values and Curves þ Ch. 11 Static Equilibrium State after Flooding Due to Damage þ Ch. 12 Deterministic Damage Stability þ Ch. 13 Probabilistic Damage Stability 2 Naval Architectural Calculation, Spring 2018, Myung-Il Roh 1 2018-08-07 Ch. 1 Introduction to Ship Stability 1. Generals 2. Static Equilibrium 3. Restoring Moment and Restoring Arm 4. Ship Stability 5. Examples for Ship Stability 3 Naval Architectural Calculation, Spring 2018, Myung-Il Roh 1. Generals 4 Naval Architectural Calculation, Spring 2018, Myung-Il Roh 2 2018-08-07 How does a ship float? (1/3) þ The force that enables a ship to float Æ “Buoyant Force” n It is directed upward. n It has a magnitude equal to the weight of the fluid which is displaced by the ship. Ship Ship Water tank Water 5 Naval Architectural Calculation, Spring 2018, Myung-Il Roh How does a ship float? (2/3) þ Archimedes’ Principle n The magnitude of the buoyant force acting on a floating body in the fluid is equal to the weight of the fluid which is displaced by the floating body.
    [Show full text]
  • Construction and Shipbuilding
    Construction and Shipbuilding Tomáš Kalina, Martin Jurkovič, Tomáš Skrúcaný, Martin Kendra SPH – Scientific Publishing Hub Osijek – Czestochowa – Žilina – Celje – Kotor 2019 Tomáš Kalina, Martin Jurkovič, Tomáš Skrúcaný, Martin Kendra CONSTRUCTION AND SHIPBUILDING /Electronic edition/ URL (e-pub): http://sphub.org/books/construction-and-shipbuilding (pdf) First electronic edition, 2019 Reviewers: Assoc. prof. ing. Dalibor Barta, Faculty of Mechanical Engineering, University of Žilina PhD. Ondrej Stopka, Institute of Technology and Business in České Budějovice, Czech Republic Lector: prof. Ing. Jozef Gnap, PhD., University of Žilina, Slovakia Illustration: authors Photography: authors Cartography: authors Design by: authors Published by SPH – Scientific Publishing Hub – founded by J.J. Strossmayer University of Osijek, Faculty of Economics in Osijek, Croatia, Czestochowa University of Technology, Faculty of Management, Poland, University of Žilina, Faculty of Operation and Economics of Transport and Communications, Žilina, Slovakia, University of Maribor, Faculty of Logistics, Celje, Slovenia, and University of Montenegro, Maritime Faculty of Kotor, Montenegro Editor in Chief: assoc. prof. dr. Borut Jereb Editorial Board: assoc. prof. dr. Borut Jereb, prof. dr. Veselin Drašković, dr. ing. Tomáš Skrúcaný, assoc. prof. dr. Davor Dujak, dr. ing. Marta Kadłubek This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License Kataložni zapis o publikaciji (CIP) pripravili v Narodni in univerzitetni knjižnici v Ljubljani COBISS.SI-ID=300897792 ISBN 978-961-6948-24-1 (pdf) Table of Contents 3 1. BASIC DATA ON VESSELS ....................................................................... 11 1.1. BASIC DIVISION OF VESSELS ................................................................... 11 1.2. DESIGN GROUPS AND BASIC PARAMETERS OF A SHIP ............................ 12 1.3. MAIN SHIP DIMENSIONS AND COEFFICIENTS OF THE SHAPE .................
    [Show full text]
  • Ship Stability Notes & Examples
    Ship Stability Notes & Examples To my wife Hilary and our family Ship Stability Notes & Examples Third Edition Kemp & Young Revised by Dr. C. B. Barrass OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd First published by Stanford Maritime Ltd 1959 Second edition (metric) 1971 Reprinted 1972, 1974, 1977, 1979, 1982, 1984, 1987 First published by Butterworth-Heinemann 1989 Reprinted 1990, 1995, 1996, 1997, 1998, 1999 Third edition 2001 P. Young 1971 C. B. Barrass 2001 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, W1P 9HE, England. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication Data A catalogue record for this book is available from the Library of Congress ISBN 0 7506 4850 3 Typeset by Laser Words, Madras, India Printed and bound in Great Britain by Athenaeum Press Ltd, Gateshead, Tyne & Wear Contents Preface ix Useful formulae xi Ship types and general characteristics xv Ship stability – the concept xvii I First Principles 1 Length, mass, force, weight, moment etc.
    [Show full text]
  • Physical Models for Simulating Ship Stability and Hydrostatic Motions
    674 Journal of Marine Science and Technology, Vol. 21, No. 6, pp. 674-685 (2013) DOI: 10.6119/JMST-012-1121-1 PHYSICAL MODELS FOR SIMULATING SHIP STABILITY AND HYDROSTATIC MOTIONS Shyh-Kuang Ueng Key words: ship motion simulator, physical-based animation, ship paper, we propose efficient physical models for simulating stability simulation, physics engine. hydrostatic ship motions caused by sea waves, cargoes and flooding water. Our physical models are based on the stability theory of ship. We widen the scope of conventional ship mo- ABSTRACT tion simulation techniques by using the gravity, buoyancy and In this paper, efficient physics models are presented for simu- meta centers of the ship to estimate the stability of the ship and lating ship hydrostatic motions caused by sea waves, cargoes compute the forces and torques acting on the ship so that the and flooding water. Based on the stability theory of ship, a ship motions can be simulated in real time. ship is regarded as a floating body whose stability is indicated Since the ship shape is irregular, it is impossible to compute by its gravity, buoyancy and meta centers. These stability the stability centers analytically. To overcome this problem, centers are influenced by cargoes, sea waves, flooding water we split the ship body into cells and distribute the ship mass, and the ship mass. Variations of these stability centers create cargoes and flooding water into the cells. Thus, the stability torques and forces which cause the ship to heave, pitch and centers, forces and torques can be computed by using finite roll.
    [Show full text]
  • Optimization of the Hull Shape of a Specialized Vessel Used to Deploy Wave Energy Converters
    ISRN UTH-INGUTB-EX- E-2015/14-SE Examensarbete 15 hp December 2015 Optimization of the hull shape of a specialized vessel used to deploy wave energy converters Simon Karl Larsson Abstract Optimization of the hull shape of a specialized vessel used to deploy wave energy converters Simon Karl Larsson Teknisk- naturvetenskaplig fakultet UTH-enheten In this study, the initial hydrostatic stability, the hydrostatic stability and the structure realibility of three different barge-shaped vessels is simulated and evaluated in order Besöksadress: to see which of the vessels would be the most optimal to use for deployment of wave Ångströmlaboratoriet Lägerhyddsvägen 1 energy converters, WECs. The vessels differ in their hull type: Bulbous-bow hull Hus 4, Plan 0 vessel, Barge hull vessel and Modified-barge hull vessel. In order to do the evaluation, the hull of each vessel is designed in DELFTship and further design is proceeded in Postadress: SolidWorks 2014. Structural strength analysis is performed in SolidWorks 2014 and Box 536 751 21 Uppsala hydrostatic properties are simualted in Ansys Aqwa 16.0. The collected results are pointing at that the Modified-barge hull vessel is slightly superior to the others in Telefon: terms of hydrostatic stability, while the structure stability is equal. 018 – 471 30 03 The results of this study will provide a foundation for further evaluation of vessels Telefax: capable of deploying wave energy converters. 018 – 471 30 00 Hemsida: http://www.teknat.uu.se/student Handledare: Irina Dolguntseva & Maria Chatzigiannakou Ämnesgranskare: Andrej Savin Examinator: Nora Masszi ISRN UTH-INGUTB-EX- E-2015/14-SE Table of Contents 1 Introduction ........................................................................................................................
    [Show full text]
  • Course Objectives Chapter 4 4. Stability
    COURSE OBJECTIVES CHAPTER 4 4. STABILITY 1. Explain the concepts of righting arm and righting moment and show these concepts on a sectional vector diagram of the ship’s hull that is being heeled over by an external couple. 2. Calculate the righting moment of a ship given the magnitude of the righting arm. 3. Read, interpret, and sketch a Curve of Intact Statical Stability (or Righting Arm Curve) and draw the sectional vector diagram of forces that corresponds to any point along the curve. 4. Discuss what tenderness and stiffness mean with respect to naval engineering. 5. Evaluate the stability of a ship in terms of: a. Range of Stability b. Dynamic Stability c. Maximum Righting Arm d. Maximum Righting Moment e. Angle at which Maximum Righting Moment Occurs 6. Create a Curve of Intact Statical Stability for a ship at a given displacement and assumed vertical center of gravity, using the Cross Curves of Stability. 7. Correct a GZ curve for a shift of the ship's vertical center of gravity and interpret the curve. Draw the appropriate sectional vector diagram and use this diagram to show the derivation of the sine correction. 8. Correct a GZ curve for a shift of the ship's transverse center of gravity and interpret the curve. Draw the appropriate sectional vector diagram and use this diagram to show the derivation of the cosine correction. 9. Determine the initial slope of the GZ curve using Metacentric Height. 10. Analyze and discuss damage to ships, including: a. Use added weight method to calculate ship trim, angle of list and draft b.
    [Show full text]
  • Parameter Optimization for Ship Antiroll Gyros
    applied sciences Article Parameter Optimization for Ship Antiroll Gyros Yuanyuan Zhu, Shijie Su * , Yuchen Qian, Yun Chen and Wenxian Tang School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China; [email protected] (Y.Z.); [email protected] (Y.Q.); [email protected] (Y.C.); [email protected] (W.T.) * Correspondence: [email protected]; Tel.: +86-135-1169-6751 Received: 26 November 2019; Accepted: 14 January 2020; Published: 16 January 2020 Abstract: Ship antiroll gyros are a type of equipment used to reduce ships’ roll angle, and their parameters are related to the parameters of a ship and wave, which affect gyro performance. As an alternative framework, we designed a calculation method for roll reduction rate and considered random waves to establish a gyro parameter optimization model, and we then solved it through the bacteria foraging optimization algorithm (BFOA) and pattern search optimization algorithm (PSOA) to obtain optimal parameter values. Results revealed that the two methods could effectively reduce the overall mass and floor space of the antiroll gyro and improved its antirolling effect. In addition, the convergence speed and antirolling effect of the BFOA were better than that of the PSOA. Keywords: parameter optimization; ship antiroll gyro; roll reduction rate 1. Introduction The stability of a ship greatly influences its crew and built-in equipment [1]. Therefore, reducing the roll motion of a ship is crucial. Compared with other ship antiroll products, antiroll gyros have advantages, such as easy installation, low energy consumption, and antiroll capability, at any speed of the ship [2,3].
    [Show full text]