Contents

License & Copyright iii

Contents. v

About this Manual 1

Chapter 1 Introduction. 2

Seakeeping Fundamentals. 3

Coordinate System.. 4

Wave Spectra. 5

Characterising Vessel Response. 7

Calculating Vessel Motions. 8

Statistical Measures. 8

Computational Methods. 8

Visualisation. 9

Chapter 2 Using Seakeeper 11

Getting Started. 11

Opening a Model in Seakeeper 11

Additional Hull Parameters. 15

Specifying Remote Locations. 17

Environmental Parameters. 19

Completing the Analysis. 22

Viewing the Results. 25

Graphing the Results. 30

Rendered view.. 33

Time Simulation and Animation. 37

Saving the Seakeeper Model 39

Saving the Seakeeping Analysis Results. 39

Limitations and Guidelines. 40

Chapter 3 Seakeeper Reference. 43

Windows. 44

Toolbars. 47

Menus. 49

File Menu. 49

Edit Menu. 50

View Menu. 50

Analysis Menu. 51

Display Menu. 52

Data Menu. 52

Window Menu. 53

Help Menu. 53

Chapter 4 Theoretical Reference. 55

Seakeeping Theory. 56

Wave Spectra Theory. 56

What the Vessel Sees. 61

Characterising Vessel Response. 62

Calculating Vessel Motions. 65

Statistical Measures. 66

Probability Measures. 67

Calculation of Subjective Magnitude and Motion Sickness Incidence. 68

Speed Loss. 71

Glossary. 73

Nomenclature. 74

Bibliography and References. 76

Appendix A Strip Theory Formulation. 80

Calculation of coupled heave and pitch motions. 81

Heave and Pitch Motion of a Vessel in a Seaway. 81

Solution of Coupled Heave and Pitch Motions. 82

Global Added Mass and Damping (Strip Theory) 83

Wave Excitation Force and Moment 85

Arbitrary Wave Heading. 85

Diffraction Force. 86

Froude-Krilov Force. 86

Head Seas Approximation. 87

Salvesen et al. (1970) Approximation. 87

Wave Attenuation (Smith Effect) 88

Added Resistance of a Vessel in a Seaway. 88

2D Ship Sections. 89

Calculation of Added Mass and Damping of 2D Ship Sections. 90

Calculation of multipole expansion coefficients. 90

Least squares solution to over-defined set of linear equations. 91

Calculation and integration of pressure functions around contour 91

Evaluation of hydrodynamic coefficients. 92

Checking the solution. 93

Important notes. 93

Added Mass at Infinite Frequency. 93

Non-Dimensional Damping Coefficient 93

Non-Dimensional Added Mass. 94

Non-Dimensional Frequency. 94

Representation of Ship-Like Sections by Conformal Mapping. 94

Derivative of Conformal Mapping. 96

Shear Force and Bending Moment due to Ship Motion in a Seaway. 96

Inertial Component 96

Hydrostatic (Restoring) Component 97

Wave Excitation Component 98

Hydrodynamic Component 98

Calculation of uncoupled roll motion. 100

Equation of motion for roll 100

Appendix B Validation. 105

Seakeeper Validation 1. 106

Introduction. 106

Analysis Procedure. 107

Results. 107

Slow Speed. 107

Moderate Speed. 108

High Speed. 108

Conclusions. 108

References. 109

Figures. 109

Seakeeper Validation 2. 128

Introduction. 128

Analysis Procedure. 128

Results. 129

Conclusions. 129

References. 129

Figures. 130

Index. 133