LOGARITHME TABLES et astronavigation OPTION: proposing an alternative approach to calculate your position at sea without the use of a scientific calculator, based on logarithm and azimuth tables
ALL THE PAGES IN RELATION TO THE LOGARITHM TABLES
EXPLANATION OF THE LOGARITHM TABLES
EXAMPLE OF HOW TO CALCULATE THE HEIGHT OF THE SUN (Hc) WITH THE TABLES
TWO EXERCISES TO CALCULATE THE HEIGHT OF THE SUN (Hc)
ADDITIONAL
TABLE 4: LOGARITHMS OF WHOLE NUMBERS
SAME NAME / NOT SAME NAME (TECHNIQUE USED IN OUR WORKSHEET)
ANCESTRAL CELESTIAL DOUWES FORMULA
THE FIVE LOGARITHM TABLES FOR DOWNLOAD PDF
LOGARITHME TABLES et astronavigation OPTION: Introduction
Logarithms tables and celestial navigation: these five tables, should be used in chronological order to gradually fill in the spreadsheet and obtain the calculated height of the sun.
NOTE:
Common logarithm tables used in the U.S.
Common logarithms (base 10) use bar notation to simplify negative values. For example, log(cos(16°)) ≈ −0.017158. You will find 9.982842 in the American tables (they added 10). This method presents the logarithm in a more user-friendly way.
I meticulously composed this chapter for individuals displaying erratic behavior and those drawn to ancestral methods. However, when I start sailing again, these tables arranged in chronological order would have the best place on my sailing boat, and I would never use a calculator again.
Logarithm table method
Logarithms are a powerful mathematical tool that allows for simplifying calculations by transforming multiplications into additions and divisions into subtractions.
This can be particularly useful when you have to perform complex calculations without the help of a calculator.
This course does not require an understanding of logarithms, but rather the use of logarithm tables.
LOGARITHME TABLES et astronavigation OPTION:
Course Method:
In fact, as a marine student, I learned to calculate the height of the sun without a calculator.
Also, I use logarithm tables to calculate the sun’s height, mainly using Douwes’ formulas.
As a matter of fact, this method follows the same principle as using a calculator. ( see worksheet for manual completing )
Moreover, you are accompanied by the interactive worksheet for these logarithm tables.
Specifically, you should start the LaRochelle exercise.
Also, at the bottom of this page, you will find the button that will take you to the interactive worksheet page for tables.
You can also access the logarithm section through the interactive worksheet tables section: height of the sun (Hc) section.
The logarithm tables: Table 1 to 5
In fact, the dedicated tables requires downloading approximately 190 pages for five different tables, and the tables must be used in chronological order.
The five tables
The five tables necessary to obtain the calculated height (Hc)
- Table 1: log cosine
- Table 2: log versine
- Table 3: natural cosine
- Table 4: logarithms of whole numbers
- Table 5: natural sine
The logarithm tables open and closed
exercises
To sum up, In the interactive worksheet page (Hc section) there are four exercises utilizing logarithm tables, fully solved and are freely accessible.
Also in the interactive worksheet page (Zv section) there are five exercises utilizing azimuth tables that have been fully solved and are freely accessible.
After completing the ‘La Rochelle’ exercise, however, for the remaining seven exercises in the exercise section, you will need to purchase the solution worksheets from the store.
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Astronavigation and Logarithm Option
Course Suitability for Marine Students
However, this course which is based on the alternative approach based on logarithm tables is less enriching for students in merchant marine schools. France formalized the use of calculators around 1980.
Undoubtedly, This course primarily caters to sailors who navigate ocean passages around the world.
Certainly, also intended for both professional mariners who operate trans ocean conveying vessels and mariners who participate in offshore races without electronic instruments.
alternative approach based on tables
In fact, with some practice, one can become faster with tables than with a calculator.
During my time as a trainee, I completed more than 300 sight calculations with the officers on board.
I almost always used my calculator, while they always used logarithm tables. However, I never beat them in terms of speed.
For instance, this method was used in the Dutch merchant navy.
From the end of the 18th century until the end of the 20th century
And its worksheet is printed in the Dutch navigation tables “Zeevaartkundige Tafels,” edition 1976.(see blow)
HAVE FUN !
**I found the name Douwes thanks to M Paul Bedel
He wrote an incredible book “navigation tables 1840-1980” Collection of the Bureau des longitudes.
The author, M Paul Bedel, is a professor and inspector general of maritime education in France.
