Ships disabled from marine disasters are generally towed by tug-boat. Issues concerning tug-towed ship systems are factors such as the length of the towing rope, the location of towing points and the conditions of the disabled ships. Up to the present time, these important factors have been entrusted to the knowledge and the experience of towing operators, and under their supervision, many accidents may occur because there isn't an effective method to tow disabled ships, towing operators are forced to use their own method, creating inconsistency and errors in methodology. In view of the development of the optimum towing method, we estimated the course stability of the tug-towed ship systems including various towing conditions. Furthermore, we examined the manoeuvring performance of the tug and the towed ship systems by using the numerical towing simulations considering wind and wave effects. The towing simulations systematically need to be done which take into account various towing conditions, and which will ultimately lead to guidelines for the safe towing operations.