Evaluation of 

 Mooring Dynamics Seminar 



Civil Engineering Laboratory 

 Port Hueneme , California 



January 10, 11, 1980 



by 

 Bruce J . Muga 



There were a number of discussions and points made during 

 this seminar that were of specific interest. They are discussed 

 below in somewhat random order. 



1. The presentation by Dr. Ochi was particularly interesting 

 since he has provided a rational explanation for what has 

 been known but for which there has been no systematic 

 development, explanation or description. This has sub- 

 stantial implication for design of systems to be deployed 

 on a short term basis, and for scheduling of the deployment. 

 It also clearly shows the site dependence of the climatic 

 conditions. On a large global scale, this is to be expected. 

 A case in point is the trade winds in the lower latitudes. 



On a smaller scale, sometimes these site dependent effects 

 are obscured by the extreme variability of other processes. 



2. The discussion concerning the second order wave force 

 determination was an important part of the seminar. Un- 

 fortunately, a number of crucial details were not available. 



A number of methods for calculating the mean wave drift 

 force were discussed. Essentially, they are: 



Method 



Hull General 



Surface Boundary or Comparisons 



Description Evaluation Specific (Accuracy) 



Newman (1967) Strip 



Far Field 



All Wave 

 Directions 



Faltinsen & 3-D Source Far Field All Wave 



Michelsen 

 (1974) 



Sink 

 (Diffraction) 



Directions 



None 



Appropriate 

 for Barges 

 (Demonstrate 

 that strip 

 theory is not 

 suitable for 

 barges) 



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