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One Tower, Two Lights

Forum to discuss all areas of lighthouse technology such as optics, fuels, fog signals, radiobeacons, daymarks, construction, etc.

Postby island » Mon Apr 28, 2008 4:50 am


It is the same idea but not nearly as precise. Many lighthouses display a sector or sectors of a different color, most often red. The light could be white with red sector or red with white sector. In either case the white is the safe area and the red identifies hazard areas around the lighthouse. These sectors are created by colored glass in the lantern or colored film on the glass but do not produce a sharp cut-off between colors as is obtained using the Directional Light.

Unlike the Directional Light when piloting a ship altering course on the changing sectors of a lighthouse light or using the boundaries between lighthouse light sectors to determine the bearing for any purpose is not recommended. One should be guided instead by the correct compass bearing to the light and not rely on being able to accurately observe the point at which the color changes. This is difficult to determine because the edges of a colored sector cannot be cut off sharply. On either side of the line of demarcation between white, red, or green sectors, there is always a small arc of uncertain color. Moreover, when haze or smoke are present in the intervening atmosphere, a white sector might have a reddish hue.
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Postby bert911 » Mon Apr 28, 2008 11:59 am


It kind of sounds like the system used on aircraft carriers to guide the pilots to the flight deck.

Remember from "TOP GUN" "Maverick ... Call The Ball"

From http://www.pprune.org/forums/archive/in ... 44920.html
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