The use of Visual Aids to Navigation
The resulting study considered responses from seagoing masters and officers, pilots, fishermen, leisure users, and authorities. Consultation involved a series of presentations to Nautical Institute members and guests in Belgium (Antwerp), Cyprus (Limassol), The Philippines (Manila), the UK (Bristol) and the USA (Houston). Sea passages were taken and some 220 individuals gave evidence. The findings of the study were sent to Lighthouse Authorities, to IALA and to the IMO Safety of Navigation Committee.
The published report, entitled The Use of Visual Aids to Navigation, highlights its purpose to determine current and future navigational practices, in order to provide a better understanding of the full value of aids to navigation. This understanding will provide a basis for risk assessment processes today and in the future.
In addition to the provision of definitions of visual aids to navigation, the phases of navigation, coastal and harbour/inland waterways are considered. A chapter is devoted to the users of aids to navigation while another very briefly outlines the history of marine aids to navigation. Current navigational techniques are considered, as well as the use of satellite, radio and radar as aids to navigation.
The report recognises that lighthouses, buoys, and beacons still comprise the greatest number of aids to navigation and that this is likely to remain so for many years
It is noted by the Lighthouse Authorities in the Great Britain and Ireland that widespread use of GPS and DGPS is encouraging mariners not only to navigate closer inshore, but to do so in conditions of darkness and reduced visibility where they would not previously have ventured. To respond to this possible disastrous situation more buoys have been established around the coasts of England and Wales and 50 existing unlighted buoys have now been fitted with lights.
Comments from accident reports and from mariners around the world demonstrate that there is overwhelming support for the continuance of visual aids to navigation. It is worthwhile to quote two anonymous statements given by those interviewed:
'If we are looking for safer ships and cleaner seas, then visual navigational aids should stay. The cost of keeping these is negligible compared to the enormous cost of accidents caused by ships due to lack of aids in terms of life, resources and clean ups after pollution, and this is applicable to all sectors of shipping.'
'I cannot see, at any time in the foreseeable future, a situation where electronic aids can safely take the place of traditional visual methods of navigation.'
Much material is taken from accident reports where such alarming comments are to be found:
'…DGPS and GPS positions were not plotted on the paper chart…the collision resulted mainly from the failure of the Master to monitor the position of the vessel…it boils down to one basic lesson, which is to look outside the window…'.
The report provides a series of valuable Conclusions and Recommendations which are reproduced in full below.
• Visual aids to navigation including buoys, beacons and shore-based lights are useful to modern mariners.
• In contravention of good practice, many small craft do not carry charts or adequate navigation aids; mariners in these vessels therefore rely on visual aids to navigation to check the position of their craft when in coastal waters.
• Large ships need to be navigated with greater accuracy due to limited sea room both in coastal waters and during pilotage. The economic and environmental consequences of a navigational accident generally increase in proportion to ship's size. Fixed and floating aids to navigation are utilised in many different ways in coastal regions, such as to mark channels, to identify hazardous wrecks, to delineate safe water around shoals and to provide orientation for safe landfalls, albeit there is a lesser need for long range landfall lights.
• Most modern deep-sea ships have alternative electronic navigation systems, but some navigators tend to rely solely on one type of navigational aid. In this context, buoys provide a valuable check both visually and on Radar for evaluating situational awareness.
• During pilotage, reliance is still placed on visual aids to navigation, both fixed and floating, for an indication of lateral positioning, for verifying progress towards alter course positions and safe channel limits, and in the case of floating aids, for early detection of set and drift.
• Buoys form a valuable check to all mariners when operating in fog or reduced visibility, where the use of buoys can verify scanty information.
• Electronic navigation aids can fail or become downgraded.
• Mariners are becoming increasingly dependent on information from electronic systems, but the interpretation of such information by some is occasionally in error.
• Visual aids to navigation reduce the frequency of navigational accidents, thus limiting consequences to the environment.
• Buoys should not be used as fixed points for navigation purposes as their positions can be subject to shifting in bad weather and ice. They can also disappear due to collision. However, used with other aids to navigation, the correct identification of buoys provides reassurance and orientation.
• Navigational practices are as diverse as the categories of operator, as is the manner in which visual aids to navigation are used.
• There is an increasing tendency for some mariners to become over reliant on electronic systems with scant regard for the vulnerability of those systems in terms of their accuracy, reliability, availability, and integrity. While future developments in GNSS, Space Based Augmentation Systems, Terrestrial Systems, DGNSS, AIS, Portable Pilot Units, and Integrated Bridge Systems will inevitably reduce these vulnerabilities, they cannot mitigate against the tendency for the modern mariners to forget to make visual checks of the external environment, and to familiarise themselves with the area in which they are operating, by reference to visual aids.
• It is inevitable that for the majority of mariners the introduction of new and more accurate satellite navigation systems, coupled with the increasing availability of reliable electronic position fixing devices and electronic chart systems at affordable prices, will eventually supersede the need for some of the traditional methods of position fixing. There will, however, be a continuing need for visual aids to navigation, albeit not so much for the purpose of position fixing but increasingly so for visual reference, and to alert the mariner to the fact that he may be standing into danger.
• Authorities when carrying out their risk assessment for safe navigation should bear these conclusions in mind, with particular respect to soliciting further feedback from all sectors of local area users.
• Training should continue to emphasise the importance and use of visual aids during passage planning and simulation exercises, with particular regard to the use of leading lights, sector lights and buoys/beacons.
• Passage planning should take into account the value of relevant visual aids to navigation, for fixing and verifying the vessel's position (fixed aids) and early detection of set and drift.
• The Nautical Institute should support the continued provision of visual aids to navigation to minimise the risk of stranding in coastal waters.
• Visual aids to navigation should continue to be used to reduce the risk of navigational errors and thus minimise the frequency of accidents and therefore the consequences to the environment.
• Visual aids to navigation should continue to be used to mark navigational hazards, such as wrecks that may not be visible on the surface.
• Visual aids to navigation should continue to be used as a means of verifying the vessel's position providing essential redundancy to electronic navigation systems.
To close, five Annexes over more than 50 pages provide a summary of grounding incidents from 1999 to 2001, extracts from Nautical Institute Marine Accident Reporting Scheme (MARS) reports, extracts from Nautical Institute presentations, and written submissions from mariners.
There is also a paper by the author, Commodore David Squire, on the subject of visual aids to navigation and their use.
The printed report entitled The Use of Visual Aids to Navigation is available from the Nautical Institute at £15.00 Stg. Copies may be obtained from the Institute at 202 Lambeth Road, London SE1 7LQ, UK. Telephone: +44 20 7928 1351; Fax: +44 20 7401 2817; or E-mail: email@example.com
Paul Ridgway is editor of the Bulletin of the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA).
This article first appeared in IALA Bulletin 2003/4, and is reproduced by kind permission.