Marine Vessel Case Study

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meters, the wind velocity almost increases linearly. Isherwood [6] has suggested a method for finding forces and moments acting on any marine vessel as shown by following Eq. (3) (2) where Cx, CY are empirical force coefficients and CN is empirical moment coefficients. ρa is the density of the air, AT and AL are transverse and lateral projected area, and L is the overall length of the ship. Isherwood has demonstrated a systematic method by which empirical coefficients can be calculated by analysing measured data through multiple regression techniques. Fig.(2) shows the effect of wind moving at a speed of 20 m/sec at 10 m height on a ship having length and breadth of 100 m and 20 m respectively…show more content…
2: Wind forces and moment on a ship of parameters, L = 100, B = 20, AL = 400, AT = 1000, and Wind speed Vr =20 m/sec of wind loads on moored ships and floating structures like pantoons using semi empirical loading functions are available in cited references [8], [9]. III. WAVE FORCES After the wind has blown constantly for a certain period of time, the sea elevation can be assumed statistically stable. In this case, the sea is referred to as fully developed sea [10]. Different wave models are used to describe fully developed sea. These models are used to derive linear approximation and thereafter used in autopilot control of marine vessels, wave filtering and state reconstructing. The most prominent spectra used in the literature are mentioned below. A. Neumann Spectrum Neumann [11] started spectral formulation by proposing one parameter spectrum as shown in Eq.(3). S(ω) = Cω−6exp(−2g2ω−2V −2) (3) where S(ω) is the wave elevation power spectral density function, C is the empirical constant, V is the wind speed, TABLE II: Definition of Sea State in terms of Significant Wave Height Sea State Description of Sea Significant Wave Height Hs(m) 0 Calm (glassy) 0 1 Calm (rippled)

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