used in Chapter II (see also [8]). In (4a) p = ^/v, and (T , 

 T and X are the propagation velocity, period, and wave length 

 of the considered wave given by (la), (2a) or (3a) as a ftinction 

 of V. If V is given in m/sec, we get H in meters by means of (4a). 

 Table 2 shows the mean wave heights at different wind velocities 

 calculated by (4a) with T = f(v) according to (la), (2a) and (3a) 

 for the three dominating waves. At moderate and high wind velocities 

 the difference between the height of these waves is small, and es- 

 pecially H^ nearly equals ^2* 



Table 2. 



Mean wave heights (meters) at different 

 wind velocities v(m/sec). 



v m/sec 2 4 6 8 10 12 14 l6 l8 20 24 



E^ 0.05 0.26 0.66 1.3 2.1 3.2 4.4 5.9 7.8 9.8 14.6 

 Hg 0.11 0.43 0.96 1.7 2.7 3.8 5.3 6.8 8.6 10.7 15.4 

 H^ 0.106 0.41 0.93 1.66 2.6 3.7 5.1 6.6 8.4 10.4 15.0 



It must be pointed out that the height of characteristic waves, 

 if taken as a mean and if considered without respect to the actual 

 wave length is less typical for the state of the sea than the steep- 

 ness of the waves, and the everchanging sequence of wave heights 

 and periods at the rough sea surface with its composite wave motion. 

 This feature also seems to be of more practical importance than any 

 average values. Steep and high waves may be dangerous for ships 

 and amphibious aircraft, aircraft carriers, etc., especially when 

 the waves run in groups and form high breakers, whereas flat swell 

 or "dead sea" even as high or perhaps higher than the steep breaking 

 waves is for the most part less dangerous or not dangerous at all 



24 



