USCG Exam PracticeChart symbols and abbreviations (Chart No. 1)
A light charted as 'Iso R 6s' has which characteristic?
- A. A red light that flashes once every 6 seconds
- ✓ A red light with equal periods of light and darkness on a 6-second cycleCorrect
- C. A red light that is interrupted once every 6 seconds
- D. A red light that occultes once every 6 seconds
Why B is correct
Isophase (Iso) means the light and dark periods are equal in duration. 'Iso R 6s' is therefore a red light with equal light and dark intervals totaling 6 seconds.