On sea charts the distances of visibility of a navigation light is usually given in nautical miles (1 nm = 6080 feet) always assuming that the observer's eye is 15 ft. above the datum depth i.e. more or less the bridge height of a small steamer.
Kwiitshati zaselwandle umgama obonakalayo okhanyayo kuqhutyo, usoloko unikwa kwiimayile zaselwandle (1nm=6080 yeenyawo) lonke ixesha qikelela imehlo lomqwalaseli lizinyawo ezilishumi elinesihlanu ngentla kobunzulu besixeli suku umzekelo ukuba nkulu okanye ukuba ncinci kobude bebrorho kwisifuthisi esincinci.