Simulation Methods Used In the Development of the Quiescent Period Prediction Systems for the Royal Navy

Simulation technology has been used effectively and extensively across many NATO nations over the past 10 years to measure performance and support the management and reduction of risk across a wide range of ship acquisition projects. Clear emphasis is being placed on managing and reducing project risks, particularly during the design stages, to minimise the likelihood of cost and time overruns. The use of simulation is routinely considered in the UK, as an alternative to traditional approaches such as scale model testing and full scale sea trials, to predict the safety and performance envelopes of platforms and systems. A NATO programme of work known as NIREUS, which is being led by UK, is now considering the use of simulation to justify and develop Quiescent Period Prediction (QPP) Systems for navies. The ability of shipboard communities to safely conduct motion sensitive tasks in high sea states is an on-going concern. It is known that in high sea states there are periods in which the ship's motion is quiescent. The purpose of NIREUS is to provide ship motion conditions and predict future ship motion with sufficient time to launch, recover and complete other motion sensitive tasks regardless of the seaway. The objective is to expand ship operating deck limits. Based on lessons learned from the use of QPP, it is conceivable, that once integrated, shipboard communities could operate in much higher sea conditions for example recovering air and sea vehicles with elevated confidence and reliability. The basis of a real QPP system is to use a wave sensor to measure the wave field ahead of the ship, so that the ship's motion can be predicted well ahead of the wave field reaching the ship. This prediction can be mapped to a speed-polar representation of the seaway around the vessel permitting ship's crew to modify ship's heading and speed to ensure the best ship condition to complete motion sensitive tasks at hand. The proposed QPP system is composed of verified/validated measurement devices reducing the need for extensive certification and testing formalities. Activities requiring either significant length of time to complete or is particularly sensitive to ship's motions, would significantly benefit from a QPP system. Several examples are presented highlighting deck recoveries of both air and sea vehicles in up to 5 metre significant wave height.