Navigation Standards

Poor position monitoring and passage planning are the proximate causes of almost all contact and grounding incidents (although not necessarily the root causes). In many cases, failure of personnel to work together as a team (Bridge Teamwork) and over-reliance on, or lack of knowledge of the use and limitations of electronic navigation systems have also been important factors.

Position Monitoring and reliance on Electronic Navigation Aids

Over the last 15 years, the practising navigator has experienced the accuracy and reliability of satellite navigation systems with hitherto unparalleled ease of use and worldwide coverage. The accuracy has been further improved by differential systems, which are now also widely used. It is hardly surprising therefore that the use of traditional systems – which generally require more active thought and effort to use – is falling into decline.

In the face of the typical accuracy and reliability of GPS, it is difficult to generate much enthusiasm for traditional methods among today’s deck officers. True, there are a few who, like many of the ‘old school’, derive real satisfaction from being able to obtain positions by the use of chronometer, sextant and almanac. However, for the majority, such activities, together with compass bearings and other visual techniques, are simply subjects for the classroom and exam: if not forgotten then consigned to the furthest recesses of the mind as largely irrelevant.

These officers generally believe that they could use traditional techniques if called upon to do so – i.e. in the case of denial of satellite service. In fact, as ‘old school’ navigators well know, it is only practice (fluency) with visual techniques which brings accuracy or consistency. A visual bearing might occasionally be taken with the comfort of a GPS position to confirm it, but being in a position where one had to rely solely on the visual position without any such confirmation is a very different matter.

Much of the ‘art’ of visual bearings lies in interpreting the chart and correctly identifying the corresponding objects: traditional navigators learned which objects would be visible, invisible, accurate, inaccurate and even misleading through a combination of practice and long experience. The navigator who plots the occasional visual bearing will not have this capability, and without electronic back up, his efforts, based on visual alone, are unlikely to be very accurate or trustworthy.

When in doubt, any navigator will revert to what he knows best: those who grew up with traditional methods will tend to revert to the visual bearings, radar range, etc. The modern navigator will be more likely to distrust these methods, instead placing his faith in electronic systems, which he believes have served him well, to date.

Perhaps this is why it is not unusual to see the modern officer disregard a visual bearing because it does not agree with the GPS. The traditionally trained officer, never having experienced the luxury of ‘certainty’ in a GPS position, would investigate any LOP which did not reasonably agree with the others – just in case it was the only one which was actually correct!

We also find that many modern navigators simply do not have the technique to be able to take satisfactory multiple bearings. In particular, few appear to have any real understanding of the importance of range and rate of change of bearing.

In parallel with the increased use of electronic position fixing systems comes a tendency to think and work in terms of latitude and longitude. This applies particularly to passage planning but also extends to anti-collision manoeuvres, where vessels now identify each other by means of Lat and Long – a practice encouraged by the Lat/Long display of the cursor position, fitted to most modern radars.

This method of working tends to reduce real positional awareness. A position given in terms of latitude and longitude does not convey the same depth of meaning as “5 miles south of the Wolf Rock” – and it certainly does not convey the sense of proximity or possibly danger. The problem is not confined to seafarers – VTS operators are often equally ‘guilty’.

ECDIS systems with real-time position information display are now widely available. It is not expensive and so is now commonly fitted on board yachts as small as 7 metres in length. This extends now to fully portable systems, which can be carried by pilots. Provided its limitations are properly understood, this affords the watchkeeper excellent “at-a-glance” positional awareness, complementing traditional position monitoring practices. Radar mapping facilities can also be used in a similar way, especially where ECDIS is not fitted.

Passage Planning

Standards of passage planning vary widely. There is a big difference between a good passage plan and the industry standard. This difference is a function of the knowledge, intelligence, skill and experience of the officer preparing the plan. A good plan is one which, by its design, assists the watchkeeper in his tasks, particularly position monitoring and collision avoidance. It does this by making intelligent use of salient landmarks, clearing ranges and bearings, beam bearings and transits both natural and man-made. Parallel indexes are simplified (to reduce the possibility of error on transfer to the radar). It also takes into account the likely tracks of other vessels, to minimise the chances of conflict. It includes all useful information and reduces the amount of time the watchkeeper has to spend behind the chart table.