Modeling And Simulation Of Towing Rig

Based on the theory of ship maneuvering mathematical model and also with the support of the concept of separated modeling theory, this paper establishs a Mathematical Model on the rig towing system. When doing so, models of tugs, propellers, rigs are established to study the towing system with full consideration of the interactions. The paper calculate the equation of maneuvering mathematical model by Runge-Kutta method, and the ship maneuvering simulation researches are carried out by use of the MATLAB's Simulink Toolbox. By quantitative and qualitative analysis, the paper discusses the motion of tow in calm water, wind and stream. With the consideration of various elements, this paper carries out a detailed research on the motion of vessel in clam water when a vessel is steering a straight course and the turning movements with different towing method.Following conclusions are reached by the comprehensive research in this paper.According to the separated modeling theory, the rig towing system model is put forward. By this Model the motions of the rig and towing lines can be exhibited.Bearing in mind the unique characteristics of rig towing system, conditions for different towing methods are given in this paper.By analyzing the variation of parameters of rigs, also with the consideration of the tension on the towing bridle and tow line, it is conducted that the optimum method for straight course towing in restricted waters is ocean-towing method.The wind and current has great effect on the safety of rig towing, and this effect will be very obvious in restricted waters. Wind will cause serious yawing during towing while current will cause sideway movement of vessels. Among various situations the most dangerous situation is when the vessel has current and wind abeam. Base on extensive simulations and with consideration of the parameters in the experiment, suggestions are put forward concerning the maximum scale of wind and current allowed in the process of towing.The rig will be subject to serious yawing in turning, which will increase the risk in ship handling. This paper simulates the turning maneuver, thorough analysis has been carried out to get the maximum course change during turning maneuver.This research describes tow's movement objectively and provides a theoretical reference for manipulation of the safety assessment of the tow. It also provides a theoretical foundation to simulation of the rig's towing system.