ssc-367 - Ship Structure Committee

H = 2*[2*ln(n) ]+*Hs
1/n
For n = 1000, this gives,
H
1/1000
= 7.43*(mO)+ = 1.86*Hs
For a given observation time, t, in hours, the most probable extreme
wave height is given by the following equation.
H max =
2*[2*mO*ln(3600*t/Tz)]%
The 3600*t/Tz is the average number of zero up-crossings in time, t.
->
A.3
WAVE SPECTRA FORMULAS
The Bretschneider and Pierson-Moskowitz spectra are the best known of
,...
the one-dimensional frequency spectra that have been used to describe
ocean waves. The JONSWAP spectrum is a recent extension of the
Bretschneider spectrum and has an additional term which may be used
to give a spectrum with a sharper peak.
A.3.1
Bretschneider and ISSC Spectrum
The Bretschneider (ReferenceA.2) spectrum and the spectrum proposed
as a modified Pierson-Moskowitz spectrum by the Second
International
Ship Structures Congress (Reference A.4) are identical.
The
Bretschneider equation in terms of radial frequency is as follows.
S(U) = (5/16)*(Hs)2*(um”/w5)*exp [-1.25*(U/Mm)-’ ]
where:
A-n