84 



Figure 5.2: Direction vectors for a short crested wave 



For the single wave method, it is expected that the individual directions will vary 

 around a central dominant direction, and the propagation direction estimate is the 

 orientation of the mean of the complex direction vectors: 



^ = ^^§1^(^51^-) 



(5.13) 



For the two wave method, it is expected that the propagation directions at each 

 point in time will vary around two dominant directions. In the case of a standing 

 wave, these two directions are clearly defined. In a more complex sea, it is not so 

 straightforward. To separate the two dominant propagation directions, the set of 

 direction vectors. Dm is divided into two sets. The two dominant directions are 

 defined as the angles of the means of the sets of direction vectors within n greater 



