UFC 4-150-06
12 December 2001
Alternating Colors. In certain instances, light characteristics consist of
alternations of colors, with either two or three colors being used in
combination. Where an alternating white and red or white and green light
is desired, the candlepower of the colors shall be equalized by selection of
the lens panels.
5-7.3.3
Visibility. The distances at which lights may be seen in clear weather are
computed for a height of the observer's eye of 4.6 m (15 feet) above sea level. Table
5-20 gives the approximate geographical range of visibility for objects of varying
elevations that may be seen by an observer whose eye is at sea level. To determine
the distance of visibility for an observer whose eye is at an elevation other than sea
level, add to the distance of visibility (determined from Table 5-20) the distance of
visibility from Table 5-20 which corresponds to the elevation of the observer's eye
above sea level.
5-7.3.4
Suppliers. Lights built to USCG specifications may be purchased from
the USCG or from a manufacturer.
Table 5-20 Distances of Visibility for Objects of Various Elevations above Sea
Level
Elevation
Distance
Elevation
Distance
Elevation
Distance
(m (ft))
(nmi)
(m (ft))
(nmi)
(m (ft))
(nmi)
1.5 (5)
2.5
21.3 (70)
9.6
76.2 (250)
18.2
3.0 (10)
3.6
22.9 (75)
9.9
91.4 (300)
19.9
4.6 (15)
4.4
24.4 (80)
10.3
106.7 (350)
21.5
6.1 (20)
5.1
25.9 (85)
10.6
121.9 (400)
22.9
7.6 (25)
5.7
27.4 (90)
10.9
137.2 (450)
24.3
9.1 (30)
6.3
29 (95)
11.2
152.4 (500)
25.6
10.7 (35)
6.8
30.5 (100)
11.5
167.6 (550)
26.8
12.2 (40)
7.2
33.5 (110)
12.0
182.69 (600)
28.0
13.7 (45)
7.7
36.6 (120)
12.6
198.1 (650)
29.1
15.2 (50)
8.1
39.6 (130)
13.1
213.4 (700)
30.3
16.8 (55)
8.5
42.7 (140)
13.6
243.8 (800)
32.4
18.3 (60)
8.9
45.7 (150)
14.1
274.3 (900)
34.4
19.8 (65)
9.2
61 (200)
16.2
304.8 (1,000)
36.2
5-7.4
Buoys. Buoys are used for lateral identification for channels in navigable
waters. Demarcation of the channel is accomplished by arranging the colors, shapes,
numbers, and light characteristics of the buoys. The standard coding system of the
USCG should be followed, where possible, and shall be obtained from that
organization. Special buoys, having no lateral significance, should be used for marking
anchorages, nets, and dredging and other special-purpose areas. For characteristics of
buoys, consult the USCG.
5-82
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