WAYPOINT - Lighting the way
George Shaw from the Royal Institute of Navigation asks whether the oldest methods of visual navigation still have a place alongside today’s evolving technology
Built in the third century BCE and operated until 1303 CE, the Pharos (Lighthouse) of Alexandria was the third longest surviving wonder of the ancient world. It was also one of the first visual aids to navigation (AtoN) ever built, guiding ships safely to port from more than 40km away. To this day, the visual cues and bearings provided by lighthouses remain important, long-term contributions to safe navigation in increasingly complex sea spaces. They are complemented by electronic aids and digital bridge systems to provide the best possible visual navigation support system for modern seafarers.
In the spirit of the great pioneers, modern developments in AtoN have built on the concept of using visual cues at sea. These have included such innovations as automation, solarisation, high performance LED arrays and 24/7 remote monitoring.
Contrast and compare
Lighthouses and other physical AtoN that operate from a precisely fixed position provide navigational resilience that is generally unmatched by current electronic navigation systems. Unlike GPS, visual cues cannot easily be jammed or spoofed. They provide a valuable complement to electronic positioning in cross-checking digital fixes, which though compellingly portrayed on ECDIS can potentially be misleading. The mariner using ‘all available means’ for safe navigation can gain reassurance from diligent use of visual cues provided by physical AtoN.
GNSS vulnerabilities may one day be further mitigated by future maritime navigation systems-of-systems, combining independent back-up technologies to safeguard the resilience of position fixing. Recent development of an enhanced pelorus (BinoNav®), a binocular instrument measuring and processing visual reference bearings, can already provide direct electronic bearing lines into ECDIS for digital position fixing. This offers seamless integration of visual navigation within an electronic navigation system, operated with minimal workload for the mariner.
Visual positioning will remain enormously valuable in this mix. However, it will still require mariner training and continued professional development to maintain traditional navigation skills which could otherwise be lost. Visual cues alert mariners immediately to the proximity of danger and aid prompt, safe routing around hazards, enabling rapid responses for urgent, safety-critical decisions.
It is interesting to compare the continued value of visual cues in modern aviation, where lights are maintained alongside numerous electronic back-up navigation systems, for which there is no maritime equivalent. For example, precision approach path indicator (PAPI) lights, akin to maritime sector lights, are still used extensively at airports as a cue to pilots, warning them of height deviations on the final approach.
Lighting the way
Traffic patterns in crowded sea basins are set to change, thanks in part to the rapid growth of offshore wind farms. Visual cues will be crucial, with lights and buoys marking the boundaries of hazardous areas, revised waypoints in more segmented passages and increasing levels of sea traffic management services. Frequent visual observation of the scene and increased situational awareness will be imperative for sea spaces where encounter rates with other vessels may increase significantly.
Physical AtoN will continue to light the way for safe navigation, eventually supporting and facilitating machine vision of emerging autonomous vessels. The practice of visual navigation may have its roots in antiquity, but it remains an essential part of the future.
Contact RIN at: www.rin.org.uk | 1 Kensington Gore, London, SW7 2AT | Tel: +44 (0)20 7591 3134