Real-Time Estimation of Natural Roll Frequency for the Stability Guidance of Fishing Vessels

Stability failures are known to be one of the major causes of accidents involving fishing vessels. The use of guidance systems, focused on complementing the capabilities of the crews for dealing with the assessment of their vessel stability, have been proposed by many authors as a possible way for reducing the frequency of this type of incidents. Initially, these systems were basically color-coded posters or were relying on subjective data introduced by the crew. However, the use of approaches which operate in real time with no need of interaction could overcome the problems identified for these “first generation” methods. This work presents a methodology based on the analysis of roll spectrum for estimating in real time the metacentric height of the vessel. The integration of the presented methodology within a first generation guidance system could increase its capabilities for providing stability guidance. The performance of the proposed methodology is analysed using the simulated roll motion of a mid-sized fishing vessel in irregular beam waves and lateral gusty wind, computed by a one degree of freedom nonlinear model. Obtained results are promising in most of the analysed conditions, although some open issues regarding the implementation of the methodology still require further analysis.