Ocean Wave Spectra and Shtp Appltcattons 
DISCUSSION 
William E. Cummins 
Naval Shtp Research and Development Center 
Bethesda, Maryland, U.S.A. 
As originally scheduled, I was to be a co-author of this Paper 
and I should to offer a word of explanation. Because of high pressures 
in the Navy Department it was not possible for me to contribute to 
this to the extent that would justify my name being on the cover. All 
the work and most of the good ideas are Dr. Chang's. I will not dis- 
sociate myself from any bad ideas, although I do not admit that there 
are any in the Paper. Fortunately Dr. Chang was able to doan ex- 
cellent job without me. She has started work in a very difficult field 
which we have all neglected, and which we must not neglect much 
longer. 
I shall say a few words about the first part of her paper on the 
problem of standard spectra, which is something we have been fight- 
ing over inthe ITTC now for some six years. I expect there will be 
a good deal of concern with it next month in Germany as well. 
The more we learn the more we realise that we are in trouble. 
We are using sea spectra in the United States Navy and we find 
that we do not know enough to use them well. I would like to offer a 
word of explanation on some of the troubles that Dr. Chang showed 
where there were discrepancies at the two ends of the ''average'"' 
spectrum. The average which was based on the fully developed spec- 
trum tended to underestimate the ends, and in the middle it tended to 
overestimate. I remember Bill Pierson warning us many times that 
when he and Neumann and Moskovitz and the others who worked on 
the fully developed spectrum, they based their theories on only 15 
percent of the measured spectra available to them, 85 percent could 
not be considered fully developed. So the naval architects who have 
been using them, against this advice of the oceanographers, have 
been concentrating on something that occurs about one time out of 
seven. 
If you have been to sea and looked with your eyes open you 
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