Detection of surf-riding behavior of ships in irregular seas

Spyrou, Kostas J.; Belenky, Vadim; Themelis, Nikos; Weems, Kenneth

doi:10.1007/s11071-014-1466-2

Cited by 22 publications

(12 citation statements)

References 12 publications

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“…Beyond simple phenomenology, "smarter" methods have also been proposed. An alternative approach is to continually calculate the instantaneous (time-varying) celerity of the wave corresponding to the origin of the ship system of axes [16], and then, to determine all time intervals when the speed has exceeded the corresponding instantaneous celerity value. In a third approach, the identification of high-runs is set up as a data clustering problem, searching for sets of trajectories in the system's phase space with the characteristics of high-run [14].…”

Section: Review Of Methods Of Identification Of Ship High-run Incidenmentioning

confidence: 99%

“…However, in an irregular sea environment the definition of celerity is debatable. It is possible to define celerity as the speed of propagation of a suitable local property of the wave profile [16]; then celerity can be calculated via a computational scheme accruing directly from this definition. However, it is also possible to calculate celerity by use of the concept of instantaneous frequency.…”

Section: Methods Based On the Up-crossing Of The Instantaneous Wave Cementioning

confidence: 99%

“…Up-crossing of the instantaneous wave celerity should initiate a high-run. Unfortunately, the instantaneous celerity suffers from frequent jumps to infinity which, whilst usually not having true physical significance for high-run occurrences, they tend nevertheless to create ambiguities in the calculation process [16]. It has been proposed, as a means towards overcoming this, to either use a local celerity value (instead of the instantaneous one), based on the point of maximum wave slope nearest to the ship [18] or to simply employ the wave celerity that corresponds to the peak frequency of the assumed wave spectrum [13,15].…”

Section: Methods Based On the Up-crossing Of The Instantaneous Wave Cementioning

confidence: 99%

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Statistical Correlations of Ship High-Run with Broaching-to and Capsize

Themelis¹,

Angelou²,

Spyrou³

2020

JMSE

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In the current paper we are extending our earlier work on the assessment of a ship’s tendency to capsize due to broaching-to in a stochastic seaway. Capturing, in a probabilistic context, interferences between different phenomena occurring during ship operation in extreme seas is a challenging task. Estimates of statistical correlations are deduced between high-run events, broaching-to and capsize. A phenomenological approach is adopted in this study for the classification of the targeted motions. Large scale simulations and a direct counting scheme are applied on the basis of a 4 degrees of freedom (4DOF) mathematical model for the coupled surge–sway–yaw–roll (and rudder) motions. Comparison with the results obtained from a previously used 3DOF model for the same scenarios is carried out in order to investigate the effect of roll on high-run’s correlation with broaching-to. Additionally, sensitivity studies are carried out in order to examine the effect of the commanded heading angle, the rudder control gains and the threshold values defining excessive (unsafe) motions. The concurrence level of the three processes considered here is found to be significantly affected by the examined parameters. The paper includes a short review of effective methods for identifying ship high-runs in following/quartering seas.

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Section: Review Of Methods Of Identification Of Ship High-run Incidenmentioning

confidence: 99%

Section: Methods Based On the Up-crossing Of The Instantaneous Wave Cementioning

confidence: 99%

Section: Methods Based On the Up-crossing Of The Instantaneous Wave Cementioning

confidence: 99%

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Statistical Correlations of Ship High-Run with Broaching-to and Capsize

Themelis¹,

Angelou²,

Spyrou³

2020

JMSE

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“…In general, the problem of celerity in irregular waves and how it can affect ship motion is a very deep problem. Spyrou et al (2014) provided a comprehensive theoretical analysis with an emphasis on the detection of surf-riding.…”

Section: Velocity Of a Profilementioning

confidence: 99%

“…The example also verifies the physical relevance of the calculated wave celerity. The method of calculating celerity based on maximum wave slope was successfully tested for identification of surf-riding by Spyrou et al (2012Spyrou et al ( , 2014. Spyrou, et al (2014a) used both methods to calculate the celerity; see Figure 21.…”

Section: Identification Of Surf-riding Instances In Irregular Wavesmentioning

confidence: 99%

On probability of surf-riding in irregular seas with a split-time formulation

Belenky¹,

Weems²,

Spyrou

2016

Ocean Engineering

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The paper reviews the status of a multi-year research effort for using the split-time method to calculate the probability of ship capsizing due to broaching-to in irregular waves. This required taking steps toward extending the existing theory of surf-riding and broaching-to, from regular waves to irregular waves and applying it to numerical simulation codes of ship motions. The extension of the theory for irregular waves leads to the formulation of a spatial-temporal framework for considering surf-riding where the celerity of irregular waves must be defined. An approximate metric for the likelihood of surf-riding in irregular waves has been proposed as the distance, in the phase plane, between the instantaneous position of a ship and the stable surfriding quasi-equilibrium at that instant. Further work includes studying the properties of the surfriding phase plane in irregular waves and statistics of surf-riding occurrences. This already complex setup becomes even more complex when, the ship motions are calculated with high accuracy, by using the more consistent, in ship hydrodynamics terms, formulation. Wave excitation can no longer be separated from stiffness while radiation and diffraction forces add a hydrodynamic memory effect. Furthermore, the irregularity of realistic ocean introduces new physical qualities to the phenomenon.The challenge to include surf-riding and broaching-to into a probabilistic assessment of stability based on advanced hydrodynamic codes has been taken up by the US Office of Naval Research (ONR) project "A Probabilistic Procedure for Evaluating the Dynamic Stability and

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