Chart Navigation & Plotting · Chart Symbols
The abbreviation 'Fl(2) 10s' beside a charted light means:
- AFixed light, 2 candela, visible 10 miles
- BA group-flashing light showing 2 flashes every 10 seconds✓ Correct
- CTwo fixed lights 10 feet apart
- DFlashing for 2 seconds, dark for 10
Explanation
Fl(2) 10s is a group-flashing characteristic: two flashes in each 10-second period. Light characteristics — including color and period — are how the navigator identifies an aid at night; the Light List gives full details.
Authority: U.S. Chart No. 1; USCG Light List
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