ssc-367 - Ship Structure Committee

From this process, the original number of sea spectra, which may have
been thousands, is reduced to the number of wave height bands times
the number of spectra in each representative set.
B.4.2
Wave Spectrum Method
A reduced set of sea spectra can be generated to represent the
variation of Hs and Tz as given in a wave scatter diagram.
If the original sea spectra are not available, a set of sea spectra
can be created directly from the wave scatter diagram. In this case
the shape of the spectrum must be assumed. For various areas of the
world’s oceans, preferred mathematical spectrum equations exist. For
the,North Sea, the mean JONSWAP spectrum is preferred. For open
ocean, the Bretschneider (ISSC) spectrum is preferred. For the Gulf
of Mexico, the Scott spectrum has been recommended.
Using the Hs and Tz for each populated box in the wave scatter
diagram, and the selected sea spectrum equation, a set of wave
spectra are defined. With this method the number of sea spectra is
reduced to the number of populated boxes in the wave scatter diagram,
but no more than the number of wave height bands times the number of
wave period band.
B–19