While navigating the St. Lawrence River downbound, the MSC Monica unexpectedly veered to starboard, exited the buoyed channel, and ran aground. Testing and examinations established that the steering gear and its control system were fully functional and that no steering failure occurred. The winds and current were not strong enough to cause the vessel’s path to change, and the vessel’s speed was not excessive for this particular type of vessel in this section of the river. The Centre for Marine Simulation (CMS) simulator was used to reproduce several scenarios under the same conditions at the time of the occurrence. The results demonstrated that the most plausible scenario for causing the vessel to initiate a veering to starboard with a rate-of-turn (ROT) of 12° per minute was that the helm was originally positioned at 10° to starboard, while the course had to be maintained at 085°gyro (G). The helmsman at the time had the expectation that the helm was positioned at 10° to port. Because the intent was to maintain the course and not veer to starboard, the initial deviation from the course was due to the helm likely being inadvertently placed 10° to starboard.
