[HN Gopher] Light characteristic
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       Light characteristic
        
       Author : altilunium
       Score  : 44 points
       Date   : 2024-02-08 13:46 UTC (1 days ago)
        
 (HTM) web link (en.wikipedia.org)
 (TXT) w3m dump (en.wikipedia.org)
        
       | rhaps0dy wrote:
       | I'm intrigued by the "Florauden seamark in Norway and its light
       | characteristics" chart in this article. It has a circle with
       | segments of different colors around the light, with different
       | descriptions. Does this mean that the Florauden light looks
       | different depending on which angle you look at it from? (i.e.
       | that it's many directional lights)
       | 
       | That could help navigate, as one could check what angle they are
       | with respect to the light; but I didn't know it was done.
        
         | joe5150 wrote:
         | Possibly an example of:
         | https://en.wikipedia.org/wiki/Sector_light
        
           | jameshart wrote:
           | Appears to be exactly that. Note that the white light
           | segments (shown in yellow and slightly extended in radius on
           | the chart) are always placed between green and red segments
           | as you move clockwise - the white segments are 'safe channel'
           | indicators of some sort.
        
         | wgrover wrote:
         | You might also find moire-effect navigation beacons
         | interesting, like the one that Tom Scott visits here:
         | https://www.youtube.com/watch?v=d99_h30swtM
        
         | gioazzi wrote:
         | Quite a few lighthouses have this characteristic, it's usually
         | one rotating light, and coloured glass for the different
         | sections. The idea is that you can safely approach the
         | lighthouse in the "white section" only, the others are for
         | guidance: green to your right and red to the left (at least
         | over here in Europe where we use IALA A, in America it's the
         | other way around). When you can see white, it should mean you
         | have a clear way towards the lighthouse. Then, as you get
         | nearer to your port, you get again a green light on your right
         | and red on the left, and that's the right way in.
         | 
         | As for where you're with respect to any light, what you need is
         | chart and compass. Usually there should be only one light with
         | a certain characteristic in the area, which you can then track
         | down in your chart. With a compass you get a bearing, and you
         | now know you're somewhere on a line. Find another lighthouse
         | (or other landmark), get the bearing, and you can know where
         | you're fairly precisely!
         | 
         | (Source: I'm getting my sailing license :-)
        
       | sllabres wrote:
       | For everyone interested in this:
       | 
       | https://geodienst.github.io/lighthousemap/
        
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       (page generated 2024-02-09 23:01 UTC)