The exercise page, titled ‘ex:La ROCHELLE FREE,’ provides simulated sextant sun sighting observations, replicating those commonly performed at sea off the coast of La Rochelle.

It is the most crucial page on this website, particularly if you are determined to master the skill of finding your position at sea without relying on GPS.

The objective is to complete the blank worksheet by recording the relevant data on this page, calculate the outcome with the help of the interactive worksheet and subsequently plotting the resulting line of position (LOP) onto a plotting sheet.

Entrance La Rochelle old harbor. Autor image: Jebulon



To begin, print or copy the worksheet by hand. Keep in mind that mastering the La Rochelle exercise will require more than a couple of hours. It may take several days to familiarize yourself with the celestial language and successfully complete the exercise independently.

And this will take time, an experience shared by every student at the naval school.

Persevere with the La Rochelle exercise until you can effortlessly complete it within 30 minutes.Once accomplished, I hope you will find the remaining exercises enjoyable and challenging

Download blank worksheet for scientific calculator or copy by hand.

EX: LA ROCHELLE FREE, image first part of the worksheet
EX: LA ROCHELLE FREE, image second part of the worksheet
png formated

After downloading or copying the worksheet by hand, we can start the exercise by completing the red entries on this page.

EX: LA ROCHELLE FREE, image of the red entries

First, we start by completing the red data.

  1. The UT time / DATE at the time of our observation.
  2. Sextant height (Hs).
  3. Index error.
  4. Non-adjustable error.
  5. Height of the eye above the sea.
  6. Estimated Latitude (L); Longitude (G).
  7. GHA, the sun’s Declination, and d for the entire UT hour.


For each entry, you will find two links. The first link will provide a theoretical explanation of the entry, and the second link will allow you to check your answer.

let's start with sextant-sun-sight-observations and exercises

1 Date and Time UT of the observation

UT TIME: 10h 40m 19s
DATE: 26/01/2022

Click on this link to check your answer.

2 sextant height (Hs)

EX: LA ROCHELLE FREE, celestial exercise sextant height
La Rochelle Hs

lower limb

Click on this link to check your answer.

3 index error

EX: LA ROCHELLE FREE, celestial exercise index error
La Rochelle index error

Click on this link to check your answer.

4 Non adjustable error

EX: LA ROCHELLE FREE, celestial exercise non adjustable error
La Rochelle

Click on this link to check your answer.

sun sight LA Rochelle:

5 eye height

EX: LA ROCHELLE FREE, celestial exercise eye height
La Rochelle

Click on this link to check your answer.

6 Dead reckoning position:

Latitude (L) :

46° 12′ North

Longitude (G) :

004° 31′ West

Click on this link to check your answer.

EXERCISE La Rochelle: The nautical almanac page

7 nautical almanac

daily page of nautical almanac

Also this daily page has been downloaded on the nauticalalmanac.it website with the kind permission of its author Capt. Roberto Iori

Note the GHA and Declination for the whole 10 UT hour; this will be explained in the interactive worksheet afterwards.

Click on this link to check your answer.

(New Haven) versageek


the red entries answers.

After the sextant sun sight and completing the red entries we check if we did not make any mistakes.

I suggest downloading or printing the completed La Rochelle worksheet PDF or copy by hand before moving on to the interactive worksheet.

Therefore, utilize the instructions offered by the interactive worksheet, which includes a theoretical note and a separate note on how to compute the different outcomes at each stage.

EX: LA ROCHELLE FREE: Click the red button of your choice now. (see below)

Highly recommended for both general use and beginners

This ancestral option is not recommended to start with.

Logarithm and azimuth tables

Finale of the La Rochelle content.

South of Argentina Patagonia Author image: PMATAS

EX: LA ROCHELLE FREE: The Importance of Persistence and Effort in Achieving Progress

As you begin with this site, it’s crucial to keep in mind that it may not provide an immediate solution to all of your problems. It’s essential to set realistic expectations and understand that working through the worksheet will take effort and time on your part. However, with dedication and persistence, you will eventually see progress.

It’s natural to want to see results quickly, but it’s important to remember that any significant change takes time. As you work through the exercises, you may encounter challenges or feel frustrated at times. Don’t be discouraged if you don’t see progress right away; it’s all part of the process.

Dolphins Red Sea Author image: Serguei S. Dukache