Lunar Distance and Age of Sail Classes:
Fascinating classes taught by a fascinating and capable instructor.
Lunars class is challenging and fun. Frank presents several different recipes for accomplishing lunars, one of which seems almost easy (kind of). Highly recommended for anyone interested in celestial navigation or nautical navigation history.
Jeffrey Rock
FAA Designated Pilot Examiner
Longitude by Lunars
"Lunar Distances" or lunars for short were used to determine longitude at sea in the period from about 1767 until 1850 (and rarely after that date). This was a time when chronometers were not yet widely available at a reasonable price and were considered unreliable on long voyages. The principle behind lunars is simple. The Moon in the sky is the hour hand of a great clock. The stars along its path are the numbers on the face of the clock. If we can measure the Moon's position relative to the stars, we can read the time from the clock. Comparing that absolute time with local time, usually determined by a time sight, we have our longitude. A one hour difference in time corresponds to a 15 degree difference in longitude.-
Predicted Lunars (UPDATED)
Traditionally, lunar distances could be used for navigation only if a navigator had access to predicted distances. These were published in almanacs around the world from the late 18th through the early 20th centuries. Today the predicted distances are no longer published, but they can be calculated without much difficulty. The predictions generated by this web site are extremely accurate. They are the most accurate available today. The time period covered is 1750 to 2050 so the predictions here can be used for modern lunars or for analysis of historical lunar observations. -
Clear a Lunar (UPDATED)
This web-based app will analyze a lunar observation and generate your longitude in a fraction of a second. Historically, the analysis of lunars required about twenty minutes of work and a table of logarithms. Even if you decide to work a lunar by hand with pencil and paper, this online calculator will allow you to check your results. Originally developed and made available online in the summer of 2004, this app has been field-tested by myself and other navigation enthusiasts thousands of times. Its results are accurate to approximately one second of arc. -
Online Nautical Almanac (UPDATED)
A complete source for Nautical Almanac ephemeris data covering the period 1750 to 2050. The positions of the Sun, Moon, navigational planets and stars are generated for every hour of the day at a high level of accuracy just as in the published almanacs. This online app permits customization of display options so that data are generated that are relevant for your location and interests. -
Easy Lunars
An account of a simple technique for analyzing lunars using nothing more than the basic corrections and data in the Nautical Almanac and a handheld calculator. Lunars are not difficult. They take a little practice, and you may have to re-familiarize yourself with the use of a calculator, but any navigator can enjoy the challenge and experience of this historical method of navigation.
Comments:
Jeffrey Rock wrote: 8👍
Greg Rudzinski wrote: 6👍
The online class "Lunars: Finding Longitude by Lunar Distance" was a very interesting introduction to the esoteric history of lunars as practiced at sea in the pre chronometer 18th century tall ship era. Practical instruction was also done demonstrating the physical process of observing a lunar with a sextant followed by a how to lunar sight reduction example using a pocket calculator, formulae, and tables. A very rewarding experience.
Greg Rudzinski
Retired Merchant Mariner
SUNY Maritime class of 80
Greg Rudzinski
Retired Merchant Mariner
SUNY Maritime class of 80
Homer Smith wrote: 10👍
Over the past few years I have taken all of the Celestial Navigation courses taught by Frank Reed at ReedNavigation.com and I recently repeated Modern CN 1 & 2 just for the pure enjoyment that it brought to me.
My interest in CN started a few years ago as I puzzled over how the stars could be used to find one’s position on the earth. I tried to learn CN through self-study, but I couldn’t make the subject matter interesting and realized that this was not the correct approach. You need a skilled instructor that can guide you through the learning process, and that’s what Frank Reed provides.
In a relatively short period of time I had a solid grounding in CN. Frank has unmatched knowledge of CN. His classes are fun, interesting, and sprinkled with historical context and include as much or as little math as you desire. His visual aids were very helpful and the time spent on discussing how to properly use a sextant to take a sight was beneficial. You will learn how to find stars in the night sky by which to navigate. The downloaded course guide is very concise and includes tables that are valid for 5 years into the future.
You don’t need to be at sea to do CN. I live inland and learned in the class how to do land-based navigation with a sextant, either with a large or small body of water to provide a true horizon, or with no water horizon at all.
Going back 250 years, I understand how CN was practiced through the ages, up to the present time with calculator, equations and tables. Thanks to Frank, I take great satisfaction in knowing that I possess a skill that very few people have. I highly recommend his courses.
Homer R. Smith M.D.
My interest in CN started a few years ago as I puzzled over how the stars could be used to find one’s position on the earth. I tried to learn CN through self-study, but I couldn’t make the subject matter interesting and realized that this was not the correct approach. You need a skilled instructor that can guide you through the learning process, and that’s what Frank Reed provides.
In a relatively short period of time I had a solid grounding in CN. Frank has unmatched knowledge of CN. His classes are fun, interesting, and sprinkled with historical context and include as much or as little math as you desire. His visual aids were very helpful and the time spent on discussing how to properly use a sextant to take a sight was beneficial. You will learn how to find stars in the night sky by which to navigate. The downloaded course guide is very concise and includes tables that are valid for 5 years into the future.
You don’t need to be at sea to do CN. I live inland and learned in the class how to do land-based navigation with a sextant, either with a large or small body of water to provide a true horizon, or with no water horizon at all.
Going back 250 years, I understand how CN was practiced through the ages, up to the present time with calculator, equations and tables. Thanks to Frank, I take great satisfaction in knowing that I possess a skill that very few people have. I highly recommend his courses.
Homer R. Smith M.D.
