Nav Light Ranges: Nominal, Luminous, and Geographic Range

An introduction to Navigational Light Range concepts including Nominal, Luminous, and Geographic Range. Includes sample problems from USCG License exams for deck officers.
Sources:
The American Practical Navigator [Bowditch]: 2002 Bicentennial Edition, Chapter 4
Sample questions from USCG question bank

[@sailingvitamins4922]

Thank YOU! For this beautiful video and an excellent explanation, step by step, with clear visual information! Game changer!!! Can not thank YOU enough 👍✨💖

[@DD-lr6ne]

Thank you very much for this video. It helps me tremendously!

[@250tuna]

Thanks for a great explanation!

[@joseargueta9156]

Hey I don’t know if you will see this message but thank you so much for not only explaining it in A very detailed manner but you also explain it for someone who just doesn’t understand the verbiage to understand as well thank you so much man this video really made me understand what we are looking for

[@maddmoney69]

Thanks for the video!

[@DanHubble]

This is very helpful for review. Thank you and well done.

[@mykeythefishamador2213]

Thank you man

[@uniquesensitivesnowflake7366]

How to solve with only using formulas? is it also possible to solve for luminous range?

[@jasonrayalfanta1993]

What height is needed to used when getting the GR, 'Tower Height' or 'Focal Height/Plane'? Thanks

[@jasonrayalfanta1993]

Coz Focal Height is greater than Tower Height.

[@deymhahaha9408]

Good morning Capt. Can you please explain to me the correct graphing in the luminous range diagram with given range and visibility problems. I hope you will notice my comment baecause I really need it to my Activity , thank you💖.

[@DD-lr6ne]

At 3:12, you show the height of the Plum Island light (actually you're looking at Pilot Island Light) you're showing it at 48' Height and 12 miles range. My question is, What does the number 15 represent just below the 48'? I see this a lot in the light list and have no idea what it means.

[@OceansUnlimited]

The bottom number that you see is the approx height of the light in meters. The top number is in feet.

[@Truthdefender101]

Im confused how you picked the nominal range? :/

[@OceansUnlimited]

The nominal range is the range listed on either the chart or the light list. It's a baseline range which you then modify according to height of eye and weather factors.

[@kirenireves]

So "Nominal Range" is just a measure of the light's power? i.e. A short light can have a long nominal range if it is very very bright (even if it can't be seen very far because it is on a short pole), and a tall light that has low power can have a low value for nominal range (even though it is high in the air)? So confusing.