What term describes the actual distance a light can be seen given light height, geometry, and meteorological conditions?

Master the Navigation, Seamanship, and Shiphandling (NSS) – Officer of the Deck (OOD) Phase 2 Exam with engaging flashcards and multiple choice questions, complete with hints and explanations. Prepare comprehensively for your test!

Actual visibility distance combines how far you can see with your own sight line and how the atmosphere affects light. The geometric part comes from the heights involved—the light’s height above the water and the observer’s eye height—which sets the horizon and thus the geographic range. Weather, on the other hand, changes how far a light remains detectable by attenuating and scattering its beam. Put together, the practical distance you can actually see the light under current conditions is called computed visibility. The other terms describe different limits: geographic range is just the geometric horizon; luminous range is how far the light could be seen under standard atmospheric conditions given its brightness; nominal range is the distance under standard meteorological conditions.