166 



NAUTICAL CHART MANUAL 



CHARACTERISTIC LIGHT PHASES 



Illustration 



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II 1 1 I I IE 



Lights which 



do not change 



color 



F. = Fixed 



F.F1. = Fixed and 

 flashing 



F.Gp.Fl. = Fixed 

 and group 

 flashing 



Fl. = Flashing 



Gp.Fl. = Group 



flashing 



Qk.Fl. = Quick 

 flashing 



I. Qk.Fl. = Inter- 

 rupted quick 

 flashing 



S-L.F1. = Short- 

 long flashing 



Occ. = Occulting 



Gp.Occ.= Group 

 occulting 



Phase Description 



A continuous steady light. 



A fixed light varied at 

 regular intervals by a flash 

 of greater brilliance or 

 different color. 



A fixed light varied at 

 regular intervals by groups 

 of two or more flashes of 

 greater brilliance or diflF- 

 erent color, or both. 



Showing a single flash 

 at regular intervals, the 

 duration of light always 

 being less than the duration 

 of darkneaa Shows not more 

 than 30 flashes per minute. 



Showing at regular 

 intervals groups of two or 

 more flashes. 



Shows not less than 60 

 flashes per minute. 



Shows quick flashes for 

 about 6 seconds, followed 

 by a dark period of about 

 6 seconds. 



Shows a short flash of 

 about 0.4 second, followed 

 by a long flash of 4 times 

 that duration. 



A steady light totally 

 eclipsed at regular inter- 

 vals. 



A steady light totally 

 eclipsed by a group of 2 or 

 more eclipses. 



Lights which 

 show color 

 variations 



Alt.= 



Alternating 



Alt.F.Fl.= 

 Alternating fixed 

 and flashing 



Alt. F. Gp. Fl. = 

 Alternating fixed 

 and group flashing 



Alt.Fl.= 



Alternating 



flashing 



Alt.Gp.Fl.= 

 Alternating 

 group flashing 



< 



Alt. Occ.= 



Alternating 



occulting 



Light colors used and abbreviations: W= White, R = Red, G = Green 



FIGURE 35— Characteristic Light Phases 



