The weather situation resulting in the peak waves is shown in 

 Figure 6; the fetch used by the author is also shown (as a solid line), 

 delineating the fetch width and decay angles. This was also essentially 

 the fetch determined by the second (independent) Board forecaster. 

 Although from the weather maps, this would appear to the author (and 

 his co-workers) to be the most accurate determination of the fetch (in 

 view of the pictured weather situation), certainly otherscould be 

 chosen. Such a fetch as shown by the dotted line, although not appearing 

 to the author to represent as closely the weather siutation pictured^ 

 on the map, might well still be possible of selection (particularly by 

 a forecaster more experienced in the use of this method) and would 

 give results much closer to those observed. 



In conclusion, it might be stated that the larger wave heights 

 forecast in this one example by the Pierson-Neumann method could result 

 from inaccurate or inapplicable determination of fetch width and 

 angular spreading, inability to accurately interpret the Co-Cumulative 

 Spectra Curves, difficulties inherent in the subjective choice of the 

 applicable meteorological parameters, and lack of experience with this 

 newer method. It should be emphasized that this paper is based on a 

 comparison of forecast methods as applied to one storm only and is per 

 se limited in its scope; no conclusions as to the relative accuracy of 

 the methods can be drawn until much wider application of the newer method 

 is made, so that some sort of statistical comparison over a long period 

 of time (as 1 year) can be made. 



REFERENCES 



1. Datz, M. - Comparison of Deep Water Wave Forecasts by the Darbyshire 



and Bretschneider Methods and Recorded Waves for Point Arguello, 

 Calif., 26-29 Oct 1950, Bull. Beach Erosion Board, V.7,Wo. k, 

 1953. 



2. Bretschneider, C. L. - Revised Wave Forecasting Curves and Procedure, 



Univ. of Calif., Inst, of Eng'g. Research, Ser. 29, no. 155-U7, 

 1951 (unpubl.) 



3. Pierson, W. J-., Jr.,G. Neumann, and R. W. James - Tech. Rpt. No. 1 



(prepared for project AROWA) N.I.O. College of Eng'g., Res. 

 Div. "Practical Methods for Observing and Forecasting Ocean 

 Waves by Means of Wave Spectra and Statistics". 



U. Kaplan, K. - Analysis of Moving Fetches for Wave Forecasting, Beach 

 Erosion Board Tech. Memo. No. 35, 1953. 



5. Beach Erosion Board - Shore Protection Planning and Design, Beach 

 Erosion Tech. Report No. ij, 195U. 



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