O Cargo Model - I 



• Cargo Model -2 



A Cruiser Model-3 



* Cruiser Model-4 



— X Destroyer Model -5 



0.6 08 10 1.2 



Tuning Factor, -A. 



Figure 10 — Comparison of Pitch and 



Heave Parameters for All 



Models at F = 0.20 



HULL PArUMETEflS 



Heave amplitude parameters for the five models are plotted in Figures 11 through 13 

 to show the relationship between heave amplitudes and beam-draft ratio. A "mean" beam- 

 draft ratio is used which is defined as the waterline beam averaged over the length 



Waterplane area 

 Length 



= C... B 



divided by the mean section draft averaged over the length 

 I Volume of displacement CgBLH 



Waterplane area 



C... B L 



= C..H 



The curves are plotted for constant Froude numbers and tuning factors. They indicate that 

 for the same Froude number and tuning factor, models with low values of C^B/C^H have 

 larger heave parameters than those with high values of C^B/C^H. This is entirely in accord 

 with theoretical considerations which show that forms with large beam and small draft have 

 good heave damping characteristics.^'^ The average rather than maximum ship dimensions 

 are used in order to obtain parameters that are more characteristic of the overall ship form, 

 and to take into account variations in underwater hull shapes. 



Families of curves, similar to those of Figures 11 through 13 for heave amplitudes, 

 are obtained for pitch amplitudes if a modified displacement-length ratio is used as the 



10 



