Method for ship’s rolling period prediction with regard to non-linearity of GZ curve

Abstract

The paper deals with the problem of prediction of the rolling period. A special emphasis is put on the practical application of the new method for rolling period prediction with regard to non-linearity of the GZ curve. The one degree-of-freedom rolling equation is applied with using the non-linear stiffness moment and linear damping moment formulas. A number of ships are considered to research the discrepancies between the pending GM-based IMO--recommended method and the results of conducted numerical simulations performed for a wide range of operational loading conditions. Since the research shows some drawbacks of the IMO formula for the ship rolling period, a new formula is worked out and proposed instead.

Multi-Objective Weather Routing of Sailboats Considering Wave Resistance

“…Neglecting this phenomenon may lead to annihilation of optimisation results, as rapid increase of rolling amplitude is in contrast to objective function criteria concerning the comfort of navigation. Further method development will also include extending the range of phenomena which are modelled and taken into account in optimisation, with particular attention focused on nonlinearities in the description of ship stability characteristics, as, according to recent literature on the subject, these nonlinearities are essential for determining the configuration of ship course and speed to avoid dangerous dynamic phenomena [26,8]. The results of past research, along with observation of possibilities to introduce new objective functions and constraints to the developed method, indicate that the planned development directions will bring the route optimisation results closer to real conditions of sailing.…”

Influence of four modern Flettner rotors, used as wind energy capturing system, on container ship stability

“…Where: l-ship width; l = 29.4 m; C-the coefficient describing ships transverse gyration radius; C = 0.371 [7] for T p ' = 9.5952 m; GM = 4.3200 m; G ' M = 4.3548 m; T-initial rolling period; T =10.4956 s; T`-the rolling period after the placement of the four modern Flettner rotors that generates green, unconventional energy; T`=10.4536 s.…”

Real-time detection of transverse stability changes in fishing vessels

“…Recently, in an attempt to maximize the ease of use and the objectivity of these guidance systems, a new group of methods has been proposed. Their main objective comprises stability evaluation by automatic real-time estimation of the vessel metacentric height (GM ) (Wawrzynski and Krata, 2016). Terada et al (2016) proposed a mathematical model to estimate the vessel roll natural frequency (directly related to GM ) together with the roll gyradius from the measured vessel roll motion.…”