Reverberation (back-scattering) is a major problem for active sonar operating in shallow waters, and detection ranges can be very sensitive to the bottom backscattering strength. This back-scattering strength is strongly area dependent, and essential environmental parameters, like bottom roughness, are seldom available. The EDA (European Defence Agency) project Rumble-2 started in 2008 and it ends in 2011. Led by Thales Underwater Systems in France, partners from the Netherlands, Norway and Sweden have also participated. A main objective has been to develop a demonstrator system for near real-time measurement of those bottom parameters necessary to estimate back-scattering and predict active sonar detection performance. The system has been implemented on a Norwegian Nansen class frigate, for its surveillance low-frequency active sonar. Several sea trials, performed in the North Sea west of Bergen, have shown that the demonstrator is robust, works well, and produces reliable estimates in agreement with available ground truth. Complemented with appropriate sonar performance modelling, a Rumble-type near real-time inversion system is most useful as a tactical decision aid to optimise the execution, and also the planning, of surveillance sonar operations. Although the Rumble system is designed for low frequency sonar, there should be no problems in extending the frequency range for use onboard Swedish vessels. Tests of this kind are proposed.