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Old 19-04-2015, 20:49   #1
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Some Celestial Stuff

I wrote and illustrated this some 20 years ago...

When published they paid for 'first Australian publishing rights' so its mine to do with as I wish.

This is 9 of 12 pieces, one day I may find the last three and upload them as well.

Some points...
1/ the Q and A's are a bit muddled and in some cases missing... and no..I won't be going looking for them..at least in the short term.
2/ a few typos slipped through the net ( I had to do my own proof reading.. never a good idea) but they would be picked up and a note included in the following month. So look ahead.

Thats it...

https://www.dropbox.com/s/oxduof5rsz...ation.pdf?dl=0
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Old 19-04-2015, 21:45   #2
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Re: Some Celestial Stuff

Oh cool, thank you. I am a nerd and like reading multiple perspectives of the same thing.

This, is, way nerdy, but since you've written a book about it: on long boring night watches I've played with making up different ways to think about sight reduction. The first time was just to assume a scientific calculator (with trigonometry), which I felt eliminated so many steps that it made it way easier.

But then I started playing with a different set of assumptions. Like, say you only care about a ~1/4 degree of accuracy, because your goal is to find an island that is visible for ~15nm. The goal is to find the island, not make landfall precisely at it's harbor in the fog. How does that allow one to simplify the whole process, eliminate steps, or change the tables?

I haven't gotten far with the idea, but it's been fun to kick around. With less accuracy there may even be a chance to replace tables with rules of thumb. Have you ever thought along that path, or read anyone that has?
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Old 19-04-2015, 22:54   #3
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Re: Some Celestial Stuff

If you are interested in navigation without GPS and sextant, try a book by David Burch "Emergency Navigation". Amazon has it here, but I'm sure you can get it elsewhere. The author goes through a few "you have X and Y, but not Z" scenarios and shows how you can still get some idea of where you are. I find it also helps with the general understanding of how navigation actually works.

There will be some who think "how likely are these scenarios?". All it takes is a lightning strike, rollover, an unexpected wave down an open companionway or even just some flat batteries, and suddenly you are missing some navigation aids.

It also makes me appreciate how easy GPS has made things!
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Old 20-04-2015, 02:37   #4
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Re: Some Celestial Stuff

Nice
Please keep looking for the 3 remaining pieces.
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Old 20-04-2015, 13:31   #5
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Re: Some Celestial Stuff

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Originally Posted by msponer View Post
......But then I started playing with a different set of assumptions. Like, say you only care about a ~1/4 degree of accuracy, because your goal is to find an island that is visible for ~15nm. The goal is to find the island, not make landfall precisely at it's harbor in the fog. How does that allow one to simplify the whole process, eliminate steps, or change the tables?

I haven't gotten far with the idea, but it's been fun to kick around. With less accuracy there may even be a chance to replace tables with rules of thumb. Have you ever thought along that path, or read anyone that has?
You need Burch's emergency navigation book... mind you, plus/minus 15 miles is probably what you will get in the early days when going for full accuracy
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Old 20-04-2015, 13:34   #6
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Re: Some Celestial Stuff

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Nice
Please keep looking for the 3 remaining pieces.
Only one was of consequence and I can't remember what it was about, the 11th was rollocks about GPS written in 1993 and the last? Well I had covered everything by the end of the 10th month so I just waffled on for 2000 words..
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Old 21-06-2015, 01:07   #7
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Re: Some Celestial Stuff

Good news and a bit of baddish news.

I've found the last 3 bits but they are in 'paper' form ( how retro is that! ).

So I need to scan, turn into PDF, convert PDF into useable text etc etc...

However, for the next month I am going to be bum up in the bottom of my boat fixing stuff....

So... this will take some time...

Only one is worth sixpence... 25 years on.

That one involves great circle sailing and includes a very simple way of working out initial GC course using the half convergency tables which as we all know were designed for correcting long range RDF bearings in high latitudes....

Watch this space.. or not.. as you wish...
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Old 21-06-2015, 01:12   #8
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Re: Some Celestial Stuff

Ok, watching this space

What's another month or so, already been waiting 25 years...
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Old 21-06-2015, 01:19   #9
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Re: Some Celestial Stuff

Just to keep you out of trouble for the next month or so....

Working out a GC distance involves simply inserting the destination lat/long into the PZX triangle in place of the LHA/Dec of a heavenly body... zenith distance = GC distance... nada mas


edited to add... pick a number... any number.... was 22 years ago... C Helmsman 1993...
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Old 02-07-2015, 05:02   #10
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Re: Some Celestial Stuff

Here's how to calculate Great Circle distance;

Distance from Position to Destination Distance = 90 - Sin-1(sin(Destination Latitude) x sin(Your present Latitude) +
cos(Destination Latitude) x cos(Your present Latitude) x
cos(Difference in Longitude between Your Location and Destination Location)

Multiply answer by 60 to get Nautical miles.
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Old 27-09-2015, 04:16   #11
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Re: Some Celestial Stuff

OK..... sorry that this is taking so long. The original 9 were done by a friend.....
I've got around to scanning the last three and making into PDFs.... I found some software that does a pretty basic job of converting them back into text but its a bit rough.

Any suggestions for a good (free) PDF to text converter? Even one with a free trial period would be good.... I only need to do about 20 pages.

TIA
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Old 27-09-2015, 05:30   #12
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Re: Some Celestial Stuff

Free PDF Tools ➥ Best Free PDF Tools | Gizmo's Freeware

Google Docs
The Best Way to Convert a PDF File to DOC for Free is with Google Docs | OSXDaily
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Old 27-09-2015, 12:03   #13
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Re: Some Celestial Stuff

Thanks , Gord, that should keep me out of mischief for a few days.
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Old 27-09-2015, 12:15   #14
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Re: Some Celestial Stuff

Back when I was sailing on the ships was not just somewhere Loran GPS when it was foggy and there clouds in the sky for a few days just is drawn on the approximate position of the ship. When the sun came out and you could see the stars immediately took the position.
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Old 25-02-2016, 14:06   #15
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Re: Some Celestial Stuff

Quote:
Originally Posted by El Pinguino View Post
I wrote and illustrated this some 20 years ago...

When published they paid for 'first Australian publishing rights' so its mine to do with as I wish.

This is 9 of 12 pieces, one day I may find the last three and upload them as well.

Some points...
1/ the Q and A's are a bit muddled and in some cases missing... and no..I won't be going looking for them..at least in the short term.
2/ a few typos slipped through the net ( I had to do my own proof reading.. never a good idea) but they would be picked up and a note included in the following month. So look ahead.

Thats it...

https://www.dropbox.com/s/oxduof5rsz...ation.pdf?dl=0

Great link, I looked through some of the pages seems well orgnized and designed book. Worth downloading. I have studied Celestail Nav years ago...with every thing if you don't use it for a number of years you need to conduct a review with good material. Now I have downloaded the 179 odd pages.

If you find the missing material let me know, I would like to have it. Most helpful Thanks. John Skoiern IV
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