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

Hello shipmates

You may have seen the post of my DIY compasses, so you may have wondered what happened to the leftover piece of triangular brass.  Well, I finally decided to either throw it out or make something....

Being one to not like wasting good material I took the piece and made a fid. 

The pic shows three splices I made from two pieces of leftover rope using my new fid.

I now have a great working fid and a new emergency dog leash besides the compasses - all from a section of 3mm bar brass and some old rope. You may not have this much salt in your scurvy bones, but I love this stuff.

Cheers    

Just Like the lack of atheism in foxholes, there are no atheists in a storm at sea. 

No one knows this better than the author of THE SQUARE RIGGED CRUISER.

http://www.survivorlibrary.com/library/t...r_1855.pdf

Call me preachy if you want, but this book of sermons directed towards sailors is a wonderful Christian read whether or not you're religeous.   The insightful and colorful marine vernacular and metaphor is eye opening and pleasing.

Do as you will, but personally I wouldn't desire to go through life without the opportunity to read this book.  At 160 years old it still speaks peace to the common man, reaching to the very core of who we are.

You might say it's a different form of Celestial Navigation.

Cheers

It's probably an old discussion, but I still dont have this clear in my head

Of course we all know that using an artificial horizon doubles the actual elevation of a body which at some point requires division by two.

The worksheets show that when taking a shot with an artificial horizon one must add or subtract index error to hs before dividing.

Im sorry but this needs explaining.  Because index error is like a constant it does not change with elevation so why add it to hs before an AH division?  The index error is then halved.   Seems to me all corrections to hs should be made after division, that means altitude correction and index error.

Stupid me just doesnt see how index error can double just because the height is doubled while using an AH.

Lets just say your index error is 20 degrees on the arc and the AH elevation is 60 degrees. So according to the work sheet you subtract 20 from 60 then divide by 2 which equals 20 degrees elevation. Dividing first then subtracting index error equals 10 degrees elevation. You can see there is a difference although index error is not likely to be this bad.

I dont currently have any ie in my sextant so it's difficult to experiment. Someone with two sextants, one way off, might have an opportunity to check out the math with observations.

Cheers

I was debating whether to call this post ah ha moment or IM SO STUPID.

Its been raining for days around here so when the clouds took a break yesterday I quickly grabbed the sextant, a plate of vegetable oil, a watch, paper and pencil, and hit the back yard.

It only took a moment to set up and I didnt have much time; the clouds were closing in again and already dimming the sun.  it was necessary to reduce the sextant shades.

I took the shot between ripples in the reflection and was satisfied I got a reasonable single shot. I immediately recorded HS and time and went inside.

I then turned on my short wave radio and dialed in WWV.  My watch proved 2 seconds fast.  No problem, I added the notation to the sight record.  I put everything aside and finished my laundry.

Later I put the sun shot to work.  I gathered my reduction stuff and sat down to work the problem.

I use a small plasticized card I developed which very briefly outlines the reduction steps.  I dont use a proforma perse,  but apply the reductiom math to any old scratch paper or notebook. I save tons of paper that way.  My reductions use as little as half a page in a pocket size notebook.

So off I went on my merry way doing the reduction then plotting Zn and the intercept...  Hmmmmm

Something wasnt right.

I've done this a hundred times, but my lop was short about 8 miles.  I began to doubt my shot and went over it in my head.  I redid the math, rechecked gmt, dec, d correction, hc, everything. I took the reduction to the dinner table - I still couldnt figure it out. I put the reduction away and turned on the big screen.

I started watching the movie CONVOY, that great old trucking classic, which moved me into a sense of persistance.  I hit the pause button and started reworking the reduction. - then it hit me... I'm sooooo stupid.

So here is the confession -  there are two ways to get the first difference for Hc.  You can do the math, dec increments/ 60 X d correction factor, or use table 5.  So I mistakenly did two thing wrong complicating the error.  I divided 60 by the increments,  then I multiplied by table 5 result.  I slapped myself in the head - hard.  24 hours later I'm still asking myself why I did that.

It literally took hours to find the error and correctly reduce the shot, but the result was absolutely satisfying.  The lop was almost spot on which boosted my confidence in taking sun shots.

I have the script writer of CONVOY to thank for instilling in me the desire to persevere.   I conquered my own ignorance and lived to tell about it.

Cheers