

*,? 



0.1 0.2 0.3 0* 0.5 f 



Figure 5. Schematic diagram. Dimensionless pitching amplitude \p m * = \p m * (F; X*; A), v* = TT. 



It is now customary to plot model results in the form 

 Z m *( A; A*) or z m ?(F; A*), 



i.e., to investigate the ship motion in a given seaway A*, as function of A or F. 



This settles the question for a given ship. 



4. Using such diagrams, the influence of variations in mass distribution and form 

 can be investigated. 



In particular, if the hull form is kept constant, the influence of changing mass 

 distribution is seen in these diagrams as the result of changing v*. 



The chosen dimensionless form of representation lends itself when L remains 

 constant. Another approach is more advantageous when L is varied. 



3.2. Inflence of Form Variations 



As example we discuss shortly the influence of variation of some basic ship 

 parameters on heave and pitch motions. The procedure is similar to that used in an 

 investigation on ship resistance [64]. It has the advantage of showing the need for 

 systematic experimental information in this field notwithstanding the large amount of 

 model work completed. Only large values of A* are considered. We treat several cases: 



1. Principal dimensions constant. J y — const. "V" versus "U" sections (increase 

 of a ). 



86 



