A method and system is utilized to produce an output corresponding to a safety level, particularly in relation to an activity on a moving body. The method involving producing an output corresponding to the ability to perform an operation within a safe limit on a moving vessel. The method comprising the steps of acquiring real time data from instrumentation on the vessel indicative of first and second elements of vessel motion relevant to the safety of the operation. Processing the data relating to each element of motion. Scaling the data relating to each element to a common scale to provide first and second values relating to the respective elements of vessel motion. Determining which value is of greatest significance and providing a output indicative of the greatest value.