Enhancing ship safety with the navigation and obstacle avoidance sonar

With an increasing trend for a wide range of users to navigate in unfamiliar coastal waters, the fact that these are often poorly charted can easily be overlooked; with potentially catastrophic results. In some areas these dangers are compounded by other submerged hazards such as debris or ice. In particular, cruise ships and large `super' yachts are frequently now operating in areas that have previously only been used by those with local knowledge, such as fishermen. The accessibility of good Global Navigation Satellite Systems (GNSS) and Dynamic Positioning (DP) underpins this basic trend, while the demand for ever more exotic leisure destinations such as the Arctic and Antarctic have accentuated this. As a consequence, many of these users have a need for real-time situational awareness of the submerged environment in order to safely operate in these areas. While the development of sonar technologies, including spread spectrum, have significantly increased the availability of high quality forward looking sonar imagery ahead of the vessel, assimilation of this into the modern integrated bridge is critical to enabling optimal use of these systems. Indeed just as the modern mariner expects their radar to complement other bridge systems such as the Electronic Chart Display and Information System (ECDIS), so sonar also needs to do so. Sonardyne has developed the Navigation and Obstacle Avoidance Sonar (NOAS) these needs in mind, using the latest Digital Signal Processing techniques including beamforming, line extraction and refraction compensation. While modern acoustic technology is central to NOAS, it has been designed in close collaboration with master mariners to ensure that it provides a capability that enhances ship safety: Consequently, simplicity of operation, as well as clear and intuitive displays at its heart, including a number of features such as a 3-Dimensional view of the ship in relation to the seabed and other detected submerged hazards overlaid in real-time on an Electronic Nautical Chart backdrop. The ability to configure alerts to warn of potential hazards and retention of sonar imagery even when these are outside the sonar's instantaneous field of view, are also important in providing full situational awareness of the seabed when maneuvering. This paper outlines how user needs have driven the design of NOAS has been designed and examples of its operational use.