🔍 Key Concepts

• Geographic range vs. luminous range – understand that geographic range depends on the heights of both the light and the observer’s eye, not the candlepower of the light • Use of Light List / Coast Pilot tables or diagram to find the geographic range when both heights are known • Effect of height of eye (32 ft / 9.8 m) on how far you can see the horizon and how that combines with the light’s height above water

💭 Think About

• First, think about how you would find the light’s height above water for Southwest Ledge Light from the Light List or Coast Pilot. What value do you need from the book? • Once you have the light’s height and your height of eye, how do the tables or curves help you combine these two heights to get a single geographic range? • Compare the approximate range you read from the table/curve with the answer options. Which option is closest to your table-derived value?

✅ Before You Answer

• Make sure you are using geographic range tables/curves, not luminous range tables • Double-check you are using the correct height of the light (focal plane height) listed for Southwest Ledge Light, not the tower height or another structure • Confirm that you are correctly converting or reading the scale in nautical miles (nm) from the table or diagram before matching to the choices