USCG Exam PracticeChart symbols and abbreviations (Chart No. 1)
A light is charted with the abbreviation 'Iso R 6s'. What does this describe?
- A. A red light that flashes once every 6 seconds with a short eclipse
- ✓ A red light with equal periods of light and darkness on a 6-second cycleCorrect
- C. A red light that is occulted for 6 seconds then lit continuously
- D. A red light with 6 flashes per minute in a group
Why B is correct
Isophase (Iso) lights have equal durations of light and darkness. 'Iso R 6s' therefore describes a red light whose on-period and off-period are equal within a total cycle of 6 seconds. (Light List — light-characteristic (Iso))