Radar can be used by itself, or in combination with more traditional methods to keep a check on your GPS plot
THE average yachtsman will probably gain most benefit from using radar as a navigation aid - especially in pilotage waters - rather than for avoiding collision. It's too easy to become impressed with the sophistication of modern electronic navigation systems, to the point where you can forget the importance of simply using your eyes to con the vessel and fIx position in clear weather. Of course this doesn't mean you shouldn't back up visual information with the appropriate electronics. Quite apart from being sensible navigational practice, to do so will help build confidence in your ability to use these systems when the need arises, most notably in restricted visibility.

Coastal navigation
To some extent, radar's role in coastal navigation has lost ground to GPS. But in restricted visibility, however, the two systems comple¬ment each other and, along with the depth sounder and any other aids, will provide useful crosschecks on your positions. I always advise stu¬dents to keep an estimated position (EP) going no matter how sophisti¬cated the navigational aids, and when in soundings always to keep a wary eye on the depth sounder. Indeed, whenever a fIx is taken, it's good practice to check the depth..
What can happen if you don't do so was vividly demonstrated in 1995 when the 32,400 ton cruise ship Royal Majesty ran aground off Nantucket. She was 17 miles off her intended track - even though she carried every conceivable naviga¬tion aid, including a navigational computer, and was manned by cer¬tificated professional offIcers. The primary cause of the stranding was that the GPS, which supplied the computer with positional informa¬tion, had failed. The computer, which was guiding the autopilot, then defaulted to dead reckoning (DR), and this hadn't been spotted by any officer for more than a whole day! In the consequent enquiry, the officers pathetically blamed the GPS, when a simple cross check against any of the other aids would have prevented the incident. The moral of the story is worth repeat¬ing: never rely on just a single aid to navigation.
So, let's see what radar can do for us around the coast, bearing in mind that its most accurate feature is its ability to measure distance.
Fixing by radar
As with visual fIxing, it's essential to positively identify any radar contact which you intend using as a naviga¬tional mark. Mistaken identifIcation, whether by radar or visualJy, has resulted in more strandings than any other cause. A mark which you might be able to see clearly visually, won't necessarily be radar conspicuous. For example, a tall chimney, may be lost in the general clutter of surrounding land signals, or a beacon or buoy could be confused with small boats navigating in close proximity. There's also a general loss of detail in the radar presenta¬tion due to the effect of beam width and pulse length, which can easily lead to false assumptions. On the other hand, steep headlands, breakwaters, jetties, small steep islands, and of course Racons, are usually easily identifIable.
When making a radar assisted landfall in very restricted visibility it's often safer to 'aim off'- in which case a down tide approach is usually best to avoid being swept on to, say, the buoy you're looking for. In any event it's most unwise to pass close upstream of any fIxed mark, especially in fog. In those circumstances, I tend to regard sight¬ing a buoy as a bonus, even if it has a sound signal.
Track monitoring by radar
The technique used to offset the EBL my vary from set to set and mightn't even be available on some. Generally speaking, however, the more sophisticated radars with azimuth stabilisation would have the offset EBL option. But, if it doesn't, you could try drawing the clearing line on the radar screen with a white board marker - of course taking care not to scratch the surface - though parallax can be a bit of a problem. Years ago on ships we used a device known as a reflection plotter which combined with a parallel index cursor. This enabled clearing lines to be drawn so that they appeared to be on the surface of the screen, thus ~ eliminating parallax.