This article aims to provide a general overwiev from operational side with regards to riser mechanics. It is utmost important to understand the movement of the riser string in the view of taking the right deciusion in case of losing platform’s position and therefore the decision for emergency disconnect. Any company operating in deep and ultra-deep wters needs to set up the decidion tree in order to safely disconnect and secure the well. The consequences of any miscommunication within an emergency situation can lead to catastrophic consequences. In the next pages an attempt will be made in order to simulate the riser string behavior given certain circumstances. Of course, this will vary from case to case depending on particular situations such as: environmental conditions, technical specifications of the vessel, the setup of riser system etc.