A series of wave height observations can be used to verify the 

 theoretical probability distribution of wave heights. Even for irregular 

 seas, the distribution may be fairly well approximated. The reliability 

 of the average height can be estimated from the size of the sample 

 and confidence limits can be assigned to the values observed. The 

 theory of truncated distributions can be used to refine the values if 

 the low waves are neglected. 



The average "period" is a misleading statistic unless it is interpreted 

 in terms of the wave spectrunn. It gives a value which is shorter than 

 the period where the maximum energy exists in the spectrum. It can 

 be forecast and thus related to the spectrum of the waves. 



The average "wave length" cannot be computed with the use of the 

 average "period" by means of the classical formulas. For a fully 

 developed sea in deep water the theoretical value is two-thirds of the 

 value that results from the classical theory. The "wave length" of an 

 individual w^ave cannot be computed from the "period" of that wave 

 as it passes a fixed point. 



The wave crest "speeds" are rarely observed, and the classical 

 formulas cannot be used to predict the "speeds" from the "periods" 

 and "lengths" in a sea. 



45 



