I just thought I'd check in to see if anyone has been using their sextants lately. 

It's rainy season in pi so the number of observation days is limited, but I vow to get something this week even if I have to guess at it.

Any other news out there?

Can't wait to hear from my  CN friends...

Cheers

Greetings,  gentlemen, (  I also  posted the same on Sight Reduction  thread)

I'm pretty  sure that many of you are familiar with  the  method,  old one, which  I recently  discovered for myself.
I refer to C.A. ("Cloudy Weather" Johnson's "Double Chronometer  Method"). I found the copy of old book  and read and tried to use this method. At first,  it looks a little bit archaic, but  as soon as you pay a little bit attention  to quite straight forward rules everything became cushty (  East London's slang for "cool."). The method doesn't require noon sight and was developed for usage at cloudy weather when sun wasn't really available.  I don't want to overload you with details, but the main  principle is:  you take two observations supposedly a couple hours apart. It may be DR and after some run- new position (  lat.  and long)  Using a few corrections the lat and long are adjusted and you got your position.  The key correction table is Table II, which is originally came from Capt.  Norie ' Tables.  Also  Pub.260 concerning Sun azimuth is used.

I'm not saying it is a magic bullet, but I found it interesting especialy considering the fact the British Navy extensively  used it and the book had 34 reprints. before 1918.  This method is also described in  Captain  Lecky's great book "Wrinkles in  Navigation."

Anyway,  just wanted to  share it with  you.

Thanks.

BTW, below you can see the basic rules to do it



1. Let two chronometer observations be taken at an interval of about 1.5-2 hours.  Let the first be worked out with the Lat. DR at the time of observation:

2. Let the Lat Dr and Long. thus obtained be corrected for the nrun of the ship in the interval  between the observations, and let the second observation be worked with this corrected latitude.  Name these Longs. (1)  and (2)

3. The bearing of the sun at each observation is to be taken from an Azimuth TAble.

4. Enter Table II (  in  Johnson's book) with the Lat and bearings, and take from it two numbers (a) and (b) of which take the difference. or sum, according as the bearings are in the same or adjacent quarters of the compass. The difference of Longs divided by this difference or sum of (a) and (b) gives the correction for the second lat.  And (a) and (b) multiplied by the correctness for latitude give the corrections for the two  longs.  Both Longs. should agree.  zif not- it shows the corrections have been wrongly applied.  A good safeguard against error., peculiar to this method only.



There are some additional  nuances which  I did not include in this basic rules.  Just for general  idea.  :>:>

Greetings,  gentlemen,

I'm pretty  sure that many of you are familiar with  the  method,  old one, which  I recently  discovered for myself.
I refer to C.A. ("Cloudy Weather" Johnson's "Double Chronometer  Method"). I found the copy of old book  and read and tried to use this method. At first,  it looks a little bit archaic, but  as soon as you pay a little bit attention  to quite straight forward rules everything became cushty (  East London's slang for "cool."). The method doesn't require noon sight and was developed for usage at cloudy weather when sun wasn't really available.  I don't want to overload you with details, but the main  principle is:  you take two observations supposedly a couple hours apart. It may be DR and after some run- new position (  lat.  and long)  Using a few corrections the lat and long are adjusted and you got your position.  The key correction table is Table II, which is originally came from Capt.  Norie ' Tables.  Also  Pub.260 concerning Sun azimuth is used.

I'm not saying it is a magic bullet, but I found it interesting especialy considering the fact the British Navy extensively  used it and the book had 34 reprints. before 1918.  This method is also described in  Captain  Lecky's great book "Wrinkles in  Navigation."

Anyway,  just wanted to  share it with  you.

Thanks.

BTW, below you can see the basic rules to do it

1. Let two chronometer observations be taken at an interval of about 1.5-2 hours.  Let the first be worked out with the Lat. DR at the time of observation:
2. Let the Lat Dr and Long. thus obtained be corrected for the nrun of the ship in the interval  between the observations, and let the second observation be worked with this corrected latitude.  Name these Longs. (1)  and (2)
3. The bearing of the sun at each observation is to be taken from an Azimuth TAble.
4. Enter Table II (  in  Johnson's book) with the Lat and bearings, and take from it two numbers (a) and (b) of which take the difference. or sum, according as the bearings are in the same or adjacent quarters of the compass. The difference of Longs divided by this difference or sum of (a) and (b) gives the correction for the second lat.  And (a) and (b) multiplied by the correctness for latitude give the corrections for the two  longs.  Both Longs. should agree.  zif not- it shows the corrections have been wrongly applied.  A good safeguard against error., peculiar to this method only.

There are some additional  nuances which  I did not include in this basic rules.  Just for general  idea.  :>:>

Hello shipmates,

Just stopped by to see if anyone is around.  Rainy season here so taking shots is less frequent.  I hope you guys are more fortunate. 

Joe

Not so... as far as I know... 

I'm just faking a post to see if anyone is paying attention.

Cheers

Try to imagine this, shipmates.

I plan to make a sort of horizon in my yard.

My plan is to use a long clear plastic thin hose filled with water to help mark a spot on my fence. The 2 hose ends will show an equal water level, so the hose snakes along the ground but is risen at both ends.  If one end is at eye height at some place where I stand to use a sextant, and the other end, perhaps 20 or 30 feet distance, is raised at the fence with a white paper tacked to the wall at the height of the water level, then I have a horizontal line of sight equal to that of the natural horizon with no dip.  As long as my eye level is steady and nearly equal to the water height in the tube, I can bring down the sun, moon, or other body to the edge of the white paper to get hs.

Instead of a white paper which would give me a very narrow azimouth, i could stretch a level, easy to see string, like orange surveyors string, along my fence to give myself more azimuth. A tight string around the whole back yard at eye height would allow a shot in any direction, but I only need, because of trees, about 45 degrees of azimouth.

Without a fence one could drive poles into the ground with which to stretch a leveled string.  I'm sure some of you could invent other ways as well to support a highly visible string at eye height.  At night for star or planet shots the string could be illuminated with a flashlight or some other means. It's not perfect, but it gives me something with which to play other than an oil filled dish. A nice lazer level would serve the same purpose - that is to mark equal eye heights at two places where one could take a shot.

So, what do you think? Does this sound doable?

Cheers.

Hello shipmates,

I dont seem to have any opportunity to get star or planet shots

I do sun shots all the time with occasional moon shots, but star and planet shots I get none.

Please get a star or planet shot, or two for fix, so I can get some practice.

Include just raw data:
DR lat/long, gmt time and date, dip height, watch error, instrument error, hs, body name.

If you use an artificial horizon please send hs after adding ic and dividing, then just mention that there is no instrument error, if any, nor dip.  

Thanks in advance

Cheers

Quick note.

The following is a quote from Frank Reed who apparently owns NAVLIST and Reednavigation.com.

This is his very racist and offensive opinion of Filipinos.

_________________________________________________

[Frank Reed: Re: Bowditch 2019 Sucks]    [Frank Reed: Re: True North and Precession]
Reply
Re: Bowditch 2019 Sucks
From: Frank Reed
Date: 2021 Feb 19, 07:57 -0800

.....Iloilo is home to a large port and a major maritime school. The Philippines remains grossly sexist, and its demented, populist president is well-known for his misogyny. Philippine maritime schools produce far more graduates than the market can support, and this naturally leads to infighting, bitterness, and jealousies within the community. Cowardly attacks on women and blustering about political correctness come easily to those at the bottom of the ladder who cannot find work.

Frank Reed



Original screenshot attached
His comments are outrageous

   

Ahoy shipmates,

Years ago before being given a fine antique sextant by a working Italian captain who I will never forget, thank you Diego, I experimented with home made devices to get altitude.  Some worked only in the day, some worked day or night.  Practicing with each I was surprised with good accuracy.

The challenge is to look around your house for tools or other likely devices that when slightly modified might serve to measure a body sufficiently to reduce a sight to within, say, half a degree. You must post an observation and reduction numbers to confirm its application. A drawing or pic is also welcome.

After hearing from those who accept the challenge I'll post my personal examples which I'm confident will intrigue you.

HINT:  The device does not need to read degrees directly, although it may, but there are other trigonometric solutions if you can find ways to measure the distance of a shadow.  :)

Have fun, be creative,  and don't put it off till tomorrow...  everyone will want to see your ideas... especially me. Just think, your idea might inspire someone to get involved and study CN.

Cheers

Pretty good stuff...

A brief sail aboard Star of India with nav processes explained laymen style.

However, although the cross staff was used as shown looking directly into the sun, I don't believe the astrolab or mariners lab was used as indicated with it held high and staring into the sun, but instead the shadow of the sun was used to get altitude info across its paddles....  Am I wrong or right?

I was surprised they did not speak of the Gunter quadrant.

Watch here:       https://m.youtube.com/watch?v=Rs81uLXGSBI