I was just watching a video about the Volvo ocean race 2014-15 and at this link;

https://youtu.be/vpM12gPOte8?t=34m32s

...it shows a sailor using a sextant.  I do not know what year they show in that excerpt of the video, as the sound is off (intentionally).  Nice to look at.

Paul

I happened upon a website which is by an artist, Sam Kerson who is a creator of the arts and is presently, with his wife, in Italy observing the refugee influx from various impoverished and torn-by-war countries.

While in Italy He spoke to a man from Gambia who sought work in Libya but ended up for many months in a Libyan prison.  Finally, the man was released.  Here are the words he spoke to Mr. Kerson about his (the Gambian man held in a Libyan prison) exodus from Libya-

We press on, “but how did you get to Europe?”  “After nine months they come and say, you go now! They have AKs’; they drive us at gun point to the beach and load us in a fiberglass boat.”

All the prisoners are asking, “Where do we go?”
“ You go out to sea! Who cares? You live you die. We need the space.”
“But we have no GPS”, the guard points with his AK and says, “Follow the north star.”


The boat they were in ran out of fuel.  As it turns out they were rescued by a ship off the coast.

Certainly a horrible story but I'm showing this as a contrast in navigational styles.  The next area North of Libya is Italy or Greece- both at quite a distance.  Following the North star would lead them directly North (true).  Now that's a quick course in celestial navigation...at gun point.

Poor folks.

Here's Mr.Kerson's website- Dragon Dance Theatre

Clear skies,

Carlos

Gentlemen, 

I just tried to use Sight reduction Astron spreadsheet / manual option and can't locate Altitude correction for Sextant sight.  Also, Index error shows only minus option. But if it is (-) should I add it instead of subtracting it from Hs? . When I entered the Height of eyes in meters the spreadsheet calc simply subtracted this number from Hs, not the data I saw in Nautical Almanac ( hard copy).  Anyway, I got a little bit different results for azimuth and intercept.

My question is: should I blindly trust the spreadsheet or paper/pencil approach? Yes it is much faster.

Again, difference about  +/- 1.5 deg. in azimuth and tolerable in the intercept results. Thank you.

Rumata has recommended a very good book- Two Years Before the Mast.

Get it here, free;

Two Years Before the Mast

It was written by Richard Henry Dana in the early 1800's and mainly describes the life and times of American merchant sailors, as Dana experienced it, aboard ship(s) trading in California.  The book provides a very thorough picture of the trip Dana took aboard Pilgrim to California and his trip back to Boston aboard Alert.

Here's excerpt from the homeward bound portion of the book from California back to Boston;

Sunday, June 5th, we were in lat. 19° 29' S., and lon. 118° 01' W., having made twelve hundred miles in seven days, very nearly upon a taut bowline. Our good ship was getting to be herself again, and had increased her rate of sailing more than one third since leaving San Diego. The crew ceased complaining of her, and the officers hove the log every two hours with evident satisfaction. This was glorious sailing. A steady breeze; the light tradewind clouds over our heads; the incomparable temperature of the Pacific,— neither hot nor cold; a clear sun every day, and clear moon and stars every night, and new constellations rising in the south, and the familiar ones sinking in the north, as we went on our course,— ``stemming nightly toward the pole.'' Already we had sunk the North Star and the Great Bear, while the Southern Cross appeared well above the southern horizon, and all hands looked out sharp to the southward for the Magellan Clouds, which, each succeeding night, we expected to make. ``The next time we see the North Star,'' said one, ``we shall be standing to the northward, the other side of the Horn.'' This was true enough, and no doubt it would be a welcome sight, for sailors say that in coming home from round Cape Horn, or the Cape of Good Hope, the North Star is the first land you make.
---------------------------------------------------------

There are a lot of books about sailing and navigation you might find interesting, here;

Books


Clear skies,

CelNav57

Greetings,

Just was astonished to find out in useful links, Calcs, in sub-calculation named Trig., that cosine 90 deg=6.12... It is not what I was taught in school. ;> I was indoctrinated that cosine  90 deg. = 0.  Live and learn. ;> ;> Definitely, some kind of glitch. I'm checking other sub. calcs. But a warning that all results from those calcs should be kinda checked for "sanity." I hope this was The only glitch.

By the way, I opened those calcs with Google Chrome.

Now you can get calendars for the years 2021 and 2022 which I call The Terrestrial Almanac.

Get them here- The Terrestrial Almanac

The calendars provide;

- all 12 months on a single page
- each month on 2 pages
- each week on 1 page
- a note sheet per month
- a cover sheet for each month (good for notes also)
- day-of-year-number and days-remaining-for-the-year for each calendar day

There are two separate calendars;

- 1 for the world which contains only season changes for both Hemispheres
- 1 for the United States which has the typical holidays, time and season changes

I hope you find them useful.

Fair winds....

CelNav57

I'm thinking I might try and take a sextant sighting of the sun (and moon) during the eclipse. It could be interesting.
I hope the clouds stay out of the way.

Dear all,
I have been starting to consider some options to buy a sextant, and I have seen that many buy sextants that a no longer produced, or 'vintage' sextants, see for example this thread. Given that sextants are highly delicate precision instruments, how do you guys make sure that you will get a sextant in proper conditions when you buy a 'vintage' one? Is there a way to identify reliable online vendors? 

For example, in the thread above Douglas Denny says:

Quote:I have various sextants but the 'best' of all was amazingly cheap costing about £200  ($240  exchange rate Jan 2016), bought about four or five years ago;  it is a Russian SNO-T and was new, unused in the original box.  These were ex-Russian Navy released presumably as surplus to requirements.

A French company has invented an electronic sextant and named it G-Stell.

Here's a link to it.

G-Stell electronic sextant

I found it while looking at links related to an upcoming boat show in France (Cannes?).  However, I have not seen that there is actual production of the G-Stell or price and availability.

It looks very promising.

CelNav57

Rumata had posted this question on another thread but I've moved and made a specific thread for his question as follows;



Gentlemen, I have a question regarding planning for twilight phenomena observation. But before some wordy stuff, sorry.

The situation: In a morning I plan for sunset phenomena observation.  I understand that below is the way to do it.:

1.  From NA find LMT for sunset, civil and nautical based on the  MOST RECENT FIX OR DR LATITUDE. ( emphasize by caps).
2. Find GMT by converting most recent fix or DR longitude into time and add/subtract it to LMT
3. Find from NA GHA of Aries for this GMT and calculate LHA of Aries
4. Pub.249 gives a list of stars as a function of LHA Aries and latitude OF THE MOST RECENT FIX OR DR.

i think that more correct approach would be:

1. Calculate assumed distance travelled considering time of civil twilight as the time of a new DR ( v* (time of last fix/DR - time of civil twilight).
2. Plot it and find latitude and longitude at the new assumed DR.
3. Using these latitude and longitude do items 1-4 from the paragraph above.

I suppose that in this case latitude and longitude would really correspond to the twilight phenomena and to LHA Aries than the values taken at the current location, presumably 10 hours earlier.

There is my question: does my guess make some sense?

Thank you