Before going into details, read this: Panbo: The Marine Electronics Weblog: HD radar, especially Furuno's
With the invention of radar
, during WW2, all you would see is a round blip on a round screen
(CRT). That was very low definition, just on or off.
There are several ways to increase "resolution" and the best way is to improve the data received by the scanner (antenna). The bigger the scanner the better, because the horizontal angle is smaller; this means that much more (smaller) sections can be scanned.
With digital radars becoming main stream, it became possible to improve the processing of received signals. At some point after introducing DSP's they started calling that HD radar
Always keep in mind that a bigger scanner is always better and this will make more difference than HD vs non-HD on modern units. But by any means, if you have selected the size scanner that you can accommodate (and stays within budget), select a HD version to further improve the image.
I would strongly suggest you take a very good look at the new Furuno
radars on 3D displays. They have some improvements that are not available on other non-commercial radars like true dual-range option and 5 scan speeds. For your boat, I would choose the smallest Furuno
radome scanner or, if you sail where fog
is abundant, the 4kW radome.
Many sailors have been unhappy with the chart catalog for the 3D series, but you can now order models that support C-Map
too, which is what I am gonna do.
Also, read more on the Panbo blog about the subject. This is the best source available.