Question 159Navigation General

70% to pass

What is characteristic of an isophase light?

A 4 sec. flash, 2 sec. eclipse, 3 sec. flash, 2 sec. eclipse
B 6 sec. flash, 3 sec. eclipse
C 1 sec. flash, 1 sec. eclipse
D 2 sec. flash, 5 sec. eclipse
AI Explanation

The correct answer is C) 1 sec. flash, 1 sec. eclipse. An isophase light is characterized by a regular, repetitive pattern of equal duration flashes and eclipses. The key characteristic of an isophase light is that the flash and eclipse periods are equal, which matches the 1 second flash and 1 second eclipse described in option C. The other options do not match the equal flash and eclipse periods required for an isophase light. Options A and B have unequal flash and eclipse durations, while option D has a much longer eclipse period compared to the flash.

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Official Resources
USCG Navigation Rules (COLREGS) 33 CFR Navigation Rules USCG National Maritime Center
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