The present disclosure provides a system and method of monitoring a mooring system for a floating vessel using the time of the natural period independent of environmental conditions. The natural period can be calculated and/or established experientially over time by measuring movement of the vessel to establish the natural period at given geographical positions of a secure and intact mooring system. The natural period can be monitored based on the time to complete a natural period. A change in a mooring line stiffness, whether by a failure, stretching, a degradation of the mooring line integrity, or a significant displacement of the anchoring point, will be translated into a different natural period with a different time. By monitoring the natural period for a given geographical position (and corresponding heading) to be compared to the theoretical values (and/or previous recorded values) it is then possible to assess that at least a portion of the mooring system has failed or that a significant damage has occurred.