356 



THEORY OF SEAKEEPING 



Damping, hydrodynamic 



force. loA. 259, 302 



in heaving and pitching, 107, 118-124, 133, 134, 135, 156, 157 



in rolhng, 127-130, 148 



moments in rolling. 125-130 



nonlinear effects, 122, 145, 140, 148, 157 



scale effect in rolling, 149 



sectional, 148 



three-dimensional, 122, 123, 145, 146 



zero valui' (in rolling), 129 

 Damping of ship vibration, 292-296, 309 

 Data-fitting technique, 80, 81 

 Deadrise, 137, 284, 308 

 Deflections, 185, 189, 264, 267, 275, 279, 292, 305 



Degrees of freedom, 



adiled In' the use of rudder, 163 



in ship motions, 164, 165 



in spectral analysis, 65-67, 69 

 Density, 



of air, 2, 8 



of water, 8, 18 

 Depth of water, effect on added masses, vibration and rolling 



ex|ieriments. 111, 127 

 Destroyer 



mndel, 155, 156, 259, 260, 275, 278-284, 286, 296-298 



observations at sea, 286-290 



Deterministic approach, or method, 166, 167, 168 



Differential equations of motion, 

 coupleil, 153 

 uncoupled, 239 



Discovery II (R.R.S.), 78, 129 



Disturbance number, 247 



Doppler shift in wave measurements, 78 



Drag, 



as fvmction of wave slope, 329 

 form or dynamic, 5, 6, 9 

 force, 3, 7, 8, 20 

 frictional, 6 

 tangential, 10 

 Dynamic 



coupling, 343 



stability of sliips on course, 163 



Dynamics of ship motion, 257 

 Dynamometers, 



frequency response of, 143 



small tletlection, 143, 145 



with high spring constants, 143 



Effective, 



dissipation factor, 336 



friction factor, 336 



friction force, 333 



shear rigidity, 292 



tangential stress, 333 

 Elastic characteristics or properties, 275, 283 

 Elastic response, 145, 149, 304-306, 309 

 Electrical analogy, 111-113, 125, 293 

 Ehsabeth (tanker), 247-250 



Ellipsoids, 



of revolution (spheroid), 108, 136, 343 



prolate, 108 



submerged, 107, 108, 130, 131 



Energy 



Ijalance, 13, 327 



density (in a spectrum), 62 



dissipation by ship-made waves, 179, 343 



dissipation in waves, 2, 3, 13, 14, 15, 24, 29, 81-84 



growth in waves, 25 



transfer from one mode of motion to another, 153, 157 



transmission or transfer from wind to water, 1, 2, 3, 15, 22, 



24, 82, 87, 320, 330, 332 

 transjiort, transfer or flow of, 85, 89, 322, 323 



Engine power reduction, 200, 237, 250 



Ensemble of functions, 61, 69 



Ergodic theorem, 59, 62, 75 



Error integral, 38 



Exciting functions, 258 



Expanding plate theory of impact, 136 



Extinction curve, 127 



Facet velocity, 10, 21, 23, 84, 87 



Fetch, 10, 13, 16, 20, 22, 29, 31, 33, 34, 41, 45-48, 50, 78, 81, 83, 

 85, 327, 332, 336 



Filtering process, 71 



Fishing trawlers, 196 



Flared bow, 276, 286, 303, 304 



Flare impact, 142, 279 



Flow, two-dimensional, 136 



Flume, 4, 6, 10, 12, 13, 15, 82 



Force, 



coefficient for lateral ship motion, 124 



damping, 107, 109, 118, 134 



displacement, 109 



due to body motions, 109 



dynamic, 150 



generated bv a how flare, 142 



inertial, 107, 108, 109, 114, 115, 258, 259 



in lateral motion, 124, 125 



in rolling, 125 



restoring, 106, 107, 109 



sectional, 109, 258 



shear, 143 



viscous, 127 



Forces, caused by, 



acceleration of water, 261, 262 

 ship acceleration, 265 

 ship oscillation, 258, 260-203 

 slamming, 136, 140, 142 

 waves, 1 14, 124, 259 



Forces 



exciting. 106, 107, 339 



gyroscopic, 182 



hydrodynamic, 106, 130, 139, 143, 153, 162, 267, 338 



hydrostatic, 265 



tangential, 9 



vibratory in lateral direction, 209 



wind-caused, 216 



Forefoot emergence, 137 



Formula velocity, 9, 213 



Fouling of sliip's bottom, 245, 246 



Fourier 



components, 30, 108 



integral, 167 



methods, 60, 61 



series (and analysis), 30, 61, 71, 75, 78, 318, 320, 325, 348 



transform, 60-63, 70, 75, 168, 175, 176, 349 



Free water surface. 111, 125, 131, 133 



Frequency, 



analyzer, 30 



bantl width, 63 



circular. 18, 37 



distribution, 2, 12, 56, 57, 59, 330, 331 



mapping. 170. 182 



Nyquist, 66, 67 



of occurence of sharp wave crests, 23 



of oscillations (effect on damping) 130 



of ship pitching in comparison with that of vibration, 115 



of two-node vibration, 136 



of wave encounter, 153, 158, 169, 239, 343 



range, 41, 123, 135 



response function, 169, 171, 177, 178 



Froude, 



assumptions in rolling 158-160 

 deviations from assiHn])tions, 159 

 Froude-Kriloff hypothesis, 115, 154, 155, 157, 163, 238, 239, 340 



