Mainsail is cutting-edge operational prototype (OP) software tool developed by CMRE staff and which is in use in daily operations by HQ Allied Maritime Command (MARCOM) staff to monitor and protect NATO critical undersea infrastructure (CUI) from sabotage.  By harnessing scalable cloud technologies, the Mainsail tool enables the efficient collection, processing, and analysis of vast amounts of data, ensuring robust data management across multiple domains.  Mainsail implements several years of CMRE research funded by ACT on the development of advanced AI, machine learning and remote sensing techniques to enhance NATO seabed-to-space situational awareness (S3A).  Mainsail represents the successful transfer of such technologies to the NATO operational community charged with securing NATO CUI, deterring future aggression by actively monitoring malign or hybrid threats, and denying any aggressor the cover of “plausible deniability”.

Staff at the NATO Maritime Centre for Security of CUI are using the CMRE Mainsail operational prototype tool on a daily basis.  The CMRE team provided direct support for bug fixing and to implement emerging requirements from the operational users of the prototype tool, including: incorporating additional data sources; vessel track playback functionalities; visualisation of incidents; and, improving the management of user alerts and urgent messages.

During 2025, in addition to improving Mainsail’s functionalities in response to HQ MARCOM staff requirements, new capabilities to monitor activity around CUI by integrating both underwater and above-water data sources were successfully tested during a dedicated sea trial.  For example, Mainsail was able to provide operators with real-time range estimates of multiple ship targets from the ambient ship noise monitored by a single passive hydrophone sensor and processed on-board the sensor platform by a novel state-of-the-art AI algorithm.