Palm distributions of wave characteristics in encountering seas

Distributions of wave characteristics of ocean waves, such as wave slope, waveheight or wavelength, are an important tool in a variety of oceanographic applications such as safety of ocean structures or in the study of ship stability, as will be the focus in this paper. We derive Palm distributions of several wave characteristics that can be related to steepness of waves for two different cases, namely for waves observed along a line at a fixed time point and for waves encountering a ship sailing on the ocean. The relation between the distributions obtained in the two cases is also given physical interpretation in terms of a ``Doppler shift'' that is related to the velocity of the ship and the velocities of the individual waves.Comment: Published in at http://dx.doi.org/10.1214/07-AAP480 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Estimating dynamic stability event probabilities from simulation and wave modeling methods

Predicting the dynamic stability of ships in severe wave environments is challenging, not only due to the complex non-linear hydrodynamics, but also the need to characterize the rarity of events. The latter involves conducting enough simulations to calculate associated small probabilities or alternate approaches for estimating the rarity of events. This paper presents techniques for calculating probabilities of occurrence of rare dynamic stability events using direct counting, Poisson distribution fitting techniques and estimating the dynamic event probabilities. The latter probability estimate is obtained by defining dangerous wave conditions that produce rare events through hydrodynamic simulations and estimating their probabilities of occurrence through joint probability distributions or simulations of the wave environment. The accuracy of these calculations is discussed. An example application is presented using a U.S. Coast Guard Cutter along with information useful for operator guidance in heavy weather. A recommendation is presented for further work on defining the limiting probabilities one might use for design or operational criteria

Extremes and related properties of random sequences and processes

Russian edition of Springer book from 198

Occurence of encountered dangerous waves

Distributions of wave characteristics of ocean waves, such as slope, amplitude or wavelength, are an important tool in the study of ship stability. In such studies, spatial properties of the sea surface at fixed time points are often considered, although it would be more interesting to study the properties of those waves that a ship actually encounters when it sails on the ocean. In this paper we derive distributions for several wave characteristics that can be related to steepness of waves for two different cases, namely for waves observed at a fixed time point and for waves encountering a ship. The distributions obtained in these two ways will not be the same and it turns out that the difference between them can be explained in terms of wave velocity