Mathematical modelling of "ASD tug - marine vessel" interaction considering tug's maneuverability and stability limitations

Abstract

The research addresses the problem of vessel-tug operation in context of tugboats' manoeuvrability and stability limitations, which are often overlooked. Proposed mathematical model of Azimuth Stern Drive tug’s dynamics considers the stability features and is used for the simulation of vessel-tug system’s dynamics in the “bow-to-bow”, “stern-to-bow” and “girting” modes. Based on the results of emergency situations’ modelling concerning a tugboat working on a towline, critical values were identified for the difference between the tug’s and the vessel’s headings, as well as the speed ratio, leading to the emergency state of the tugboat. The list of such conditions is presented in the article and may be used as recommendations when planning and monitoring the vessel-tug system’s operation.