Ship Stability: Notes and Examples (eBook)

Cover 1
Copyright Page 5
Contents 6
Preface 10
Useful formulae 12
Ship types and general characteristics 16
Ship stability – the concept 18
Chapter I. First Principles 19
Length, mass, force, weight, moment etc. 19
Density and buoyancy 20
Centre of Buoyancy and Centre of Gravity 21
Design co-efficients: Cb, Cm, Cw, Cp and CD 22
TPC and fresh water allowances 28
Permeability ‘µ’ for tanks and compartments 32
Fulcrums and weightless beams 34
Chapter II. Simpson’s Rules – Quadrature 37
Calculating areas using 1st, 2nd and 3rd rules 37
VCGs and LCGs of curved figures 46
Simpsonising areas for volumes and centroids 47
Comparison with Morrish’s rule 49
Sub-divided common intervals 6
Moment of Inertia about amidships and LCF 52
Moments of Inertia about the centreline 52
Chapter III. Bending of Beams and Ships 54
Shear force and bending moment diagrams for beams 54
Strength diagrams for ships 63
Chapter IV. Transverse Stability 69
Transverse Stability (Part 1) 69
KB, BM, KM, KG and GM concept of ship stability 69
Proof of BM D I/V 70
Metacentric diagrams 72
Small angle stability – angles of heel up to 15° 75
Large angle stability – angles of heel up to 90° 76
Wall-sided format for GZ 78
Stable, Unstable and Neutral Equilibrium 80
Moment of weight tables 84
Transverse Stability (Part 2) 92
Suspended weights 92
Inclining experiment/stability test 94
Deadweight–moment curve – diagram and use of 97
Natural rolling period TR – ‘Stiff’ and ‘tender’ ships 99
Loss of ukc when static vessel heels 102
Loss of ukc due to Ship Squat 104
Angle of heel whilst a ship turns 105
Chapter V. Longitudinal Stability, i.e. Trim 107
TPC and MCT 1 cm 107
Mean bodily sinkage, Change of Trim and Trim ratio 109
Estimating new end drafts 114
True mean draft 119
Bilging an end compartment 121
Effect on end drafts caused by change of density 122
Chapter VI. Dry-docking Procedures 125
Practical considerations of docking a ship 125
Upthrust ‘P’ and righting moments 126
Loss in GM 127
Chapter VII. Water and Oil Pressure 129
Centre of Gravity and Centre of Pressure 129
Thrust and resultant thrust on lockgates and bulkheads 131
Simpson’s rules for calculating centre of pressure 134
Chapter VIII. Free Surface Effects 137
Loss in GM, or Rise in G effects 137
Effect of transverse subdivisions 140
Effect of longitudinal subdivisions 141
Chapter IX. Stability Data 143
Load line rules for minimum GM and minimum GZ 143
Areas enclosed within a statical stability (S/S) curve 145
Seven parts on an statical stability (S/S) curve 147
Effects of greater freeboard and greater beam on an S/S curve 148
Angle of Loll and Angle of List comparisons 150
KN cross curves of stability 152
Dynamical stability and moment of statical stability 154
Chapter X. Carriage of Stability Information 156
Information supplied to ships 156
Typical page from a ship’s Trim & Stability book
Hydrostatic Curves – diagram and use of 160
Concluding remarks 163
Appendix I. Revision one-liners 165
Appendix II. Problems 168
Appendix III. Answers to the 50 problems in Appendix II 176
Appendix IV. How to pass exams in Maritime Studies 179
Index 181