RU2091269C1 - Method of check of ship's stability - Google Patents

Abstract

FIELD: shipbuilding. SUBSTANCE: method consists in measuring the ordinates of swell and roll processes, determining spectral densities and relationship of periods corresponding to frequency of maximum magnitudes of swell and roll spectrum. Then natural roll period and metacentric height are calculated. EFFECT: enhanced reliability. 1 dwg

Description

 The invention relates to shipbuilding, in particular to methods for monitoring stability under the conditions of operation of the vessel, and can be used in the development of navigation expert systems.

 Closest to the proposed is a method of monitoring the stability of the vessel, which consists in measuring the side rolling and determining the estimated metacentric height (see Sevastyanov NB Stability of fishing vessels. L. Sudostroenie, 1970, p. 187-190).

 However, it does not provide a reliable estimate of the stability of the vessel under operating conditions with a strong difference between the periods of forced and natural oscillations.

 The technical result of the invention is to increase the reliability of the assessment of the stability of the vessel.

 This is achieved by the fact that in the known method, when determining the metacentric height, the draft is further measured with bow and stern, the apparent wave period, heading angle, the speed of the vessel on irregular waves and the ordinates of the processes of wave and rolling.

 The drawing shows a functional diagram of a device that implements this method.

 The device comprises a pitching sensor 1, sensors 2 and 3 of the draft of the vessel bow and stern, a wave sensor 4, a switch 5, an analog-to-digital converter 6, an interface 7, a computer 8, a display 9, a printer 10.

 The method is as follows.

 The rolling period of the draft of the vessel’s draft of the bow and stern, the apparent period of the wave are measured, and the ordinates of the processes of wave and rolling are measured at the same time.

где K_ξ(τ) и K_θ(τ) корреляционные функции измеренных случайных процессов волнения x(t) и бортовой качки θ(t); σ круговая частота; t временной сдвиг;
периоды колебаний, соответствующие частоте максимумов спектральной плотности волнения и бортовой качки.According to the measurements establish:
spectral wave densities S ₃ (σ) and roll heights S _θ (σ)

where K _ξ (τ) and K _θ (τ) are the correlation functions of the measured random processes of the waves x (t) and the roll θ (t); σ circular frequency; t time shift;
oscillation periods corresponding to the frequency of the maxima of the spectral density of the waves and rolling.

где σ_ξm и σ_θm частоты максимумов кривых спектральной плотности волнения и бортовой качки;
собственный период бортовой качки

где

измеренные значения курсового угла, периода и средней амплитуды бортовой качки; τ_о период бортовой качки при выходе судна в рейс;
метацентрическая высота
h = B²(0,7487+0,0456В/T-0,000874L)²/ τ $\genfrac{}{}{0ex}{}{\text{2}}{\text{с}}$ , (3)
где L, B, T главные размерения судна.

where σ _ξm and σ _{θm are the} frequencies of the maxima of the spectral density curves of the waves and rolling;
own rolling period

Where

measured values of heading angle, period and average amplitude of rolling; τ _about the rolling period when the vessel enters the voyage;
metacentric height
h = B ² (0.7487 + 0.0456V / T-0.000874L) ² / τ $\genfrac{}{}{0ex}{}{\text{2}}{\text{from}}$ , (3)
where L, B, T are the main dimensions of the vessel.

 Functional diagram that implements the method of stability control works as follows.

 Measurement data from sensors 1-4 through switch 5, analog-to-digital converter 6, and interface 7 are received for further processing in computer 8, where operations are performed to analyze the initial information and evaluate stability by expressions (1) - (3), the results of which are demonstrated using the printer 10.

Claims (1)

 A method of controlling the stability of a ship, which consists in measuring side rolling and determining by calculating the metacentric height, characterized in that when determining the metacentric height, the draft of the vessel is measured further with bow and stern, the apparent wave period, heading angle, the speed of the vessel on irregular waves and the ordinates of the processes of wave and onboard pitching.