Well, at the end of last season I bought and fitted a NASA AIS "radar". I gave it its own antenna on the pushpit. The first time out it got used in earnest.
We were returning to Brussels down the Westeschelde early in the morning when the fog rolled in. Good quality, can't-see-your-bow-from-your-stern fog that is. Now the Schelde probably classes as a busy river, leading as it does to Antwerp docks, and it has a respectable current of 2 to 4 knots, which is handy, if you have it with you. It was a case of navigating from one buoy to the next by radar, whilst trying to avoid hitting them. The radar is quite difficult to correlate with a chart in a river (one good reason to have them superimposed on a chart plotter). The river banks give no clear indication and the Schelde banks are in many places far from the navigable channel. Then there are all the other targets. Some are the buoys. Some are big blobs with a matching AIS signature, Some big blobs have no AIS signature. Several randomly appearing and vanishing small blobs turned out to be other yachts.
So, lessoned learned:-
- Radar is king in fog
- AIS helps identify the big guys
- Yachts have rotten radar signatures - AIS would help.
Having now used the NASA AIS for a whole season, I have found it very useful, but it will have to be replaced. The north-up screen orientation needs correlating with the course-up radar image and both need correlating with the chart. Also my NASA AIS has a habit of suddenly loosing all targets and needs resetting.
But getting a chartplotter and radar and AIS transceiver that all work nicely together is going to be one big Christmas present.