🔍 Key Concepts

• Geographic range of visibility vs. luminous range of a light • Using the light list or charted information for height of light and your height of eye • Relating distance off a point (from your DR track and time–distance–speed)** to when the light drops below the horizon**

💭 Think About

• First, figure out how far away Montauk Pt. Light will be when it just disappears below the horizon. What formula connects distance to horizon with height of light and height of eye? • From your plotted course toward Great Salt Pond, at what DR position (time) are you at that distance from Montauk Pt. Light? • Is the limiting factor the light’s brightness or the earth’s curvature, given that visibility is stated as unlimited?

✅ Before You Answer

• From the chart or Light List, note the height of Montauk Pt. Light and your vessel’s height of eye as given in the problem setup. • Compute the geographic range using the standard distance-to-horizon formula for both heights and add the results. • On your track line, mark the point where your distance off Montauk Pt. equals that geographic range and read the corresponding time from your DR plot before choosing an answer.