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Old 08-06-2008, 07:28   #31
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Quote:
Originally Posted by DragonFlyer View Post
Bill, hi
This reply comes 2 years late, but what the heck. I believe your problem comes from your altitude correction. The proper correction is 14.5 arc minutes, whereas you turned it into 14.66 degrees (a 60x error!).

I have written a celestial navigation book which is free to download. You can get "The Armchair Celestial Navigator" at my web site: Celestial Navigation

Rodger
Nice. I downloaded the book and the Excel spreadsheet.

But, off topic, I'm having the most fun reading the "designing_model_cargo_ships" guide from the miscellaneous section of your site. Is there any place that shows the actual competitions? Or photos of the ships the students built? I ask in here (instead of e-mailing you from your site) because I think some people in here might be interested. If this turns into a discussion, we should start another thread...

-dan
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Old 08-06-2008, 17:35   #32
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Very generous of you DragonFlyer - a lot of effort went into that book. Thanks - goin' to look at Lunars (just out of interest tho' ).

John
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Old 29-12-2008, 12:11   #33
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Looseends:

H.O. 249 and 229, or Publication 229 and 249 as they are now known can either be purchased or obtained as free downloads via the internet. Google H.O. 229, and or 249, and follow the references.

Re the Nautical Almanac, it's a yearly publication, though some of the data from the 2008 edition can be used for a couple of years, with noted corrections. The government editions (hardcovered) usually run $35 or more, the commercial edition, same data, soft covered, with a few pages of ads at the back of the book are a good bit lower in price. Take your pick.
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Old 29-12-2008, 15:14   #34
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A caveat about the on-line version of H.O. 249. Two sets of errors crept into it. One error (data formatting that, for example, turned "-0 59" into "00 59") has been corrected but there appear to be gross computational errors that, AFAIK, have not been corrected. Unfortunately, I'm about 3,000 miles from the notes on this issue, although I believe I posted them here and know I posted them to the SSCA forum. For that posting and related comments click here.

Bottom line: the on-line version is somewhat suspect and should be avoided until the problems have been sorted out. In the interim, I recommend buying a printed set from Celestaire and contacting Ken Gebhart at Celestaire before placing the order, as some printed editions may have been corrupted, too. (Celestaire carries the Nautical Almanac, too)

- - -

In any case, the printed version of HO 249 is easier to work with because an entire page can be viewed at once, as opposed to scrolling around to match row and column. The on-line version is in PDF form and can be scaled to fit a whole page to a screen, but the contents will most likely be too small to read easily.
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Old 29-12-2008, 23:29   #35
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I downloaded your book. thanks. Now, if my thick head can absorb.
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Old 29-12-2008, 23:42   #36
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RBEmerson:

There are a number of ways to skin this cat. H.O. 229, 249 and the old Ageton Method that used to be printed in Bowditch, not sure if it's in the latest, the Bi-centenial edition, perhaps some others of which I'm unaware. Personally, I find the Nautical Almanac to be quite straight forward, which might just show my lack of understanding. In any event, it's just one book, and even if you get a new one yearly, the commercial editions are inexpensive, especially when one looks at the costs of boats and or the runnig thereof. Several acquaintances of mine, all of whom are boat owners, both power and sail, agree on one thing. A boat is a hole in the water, into which one throws endless amounts of money.
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Old 30-12-2008, 05:08   #37
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Ageton is long gone from Bowditch. In fact, it's one reason I went in search of an edition that had the tables (the price of older twentieth century editions of Bowditch can be startling). You can get Bowditch on-line from the same site carrying HO 249 (in fact, there are a number of useful publications there). AFAIK, it doesn't suffer from formatting or computation errors.

As to using 229, 249, Ageton or other methods (Hewitt Schlereth came up with some interesting tables, for example), keep in mind that the choice in landlocked SW PA may not be the same offshore, where the crew can be stupid tired and cranky from being wet and bounced around; "short and simple" helps here.

For the truly parsimonious, keep in mind that all you really need are four copies of the Nautical Almanac, after that, the data is surprisingly close when using, for example, the 2003 NA in 2007 (IIRC, not true for 2000 - why is left as an exercise for the student).

Added:
BOAT = Break Out Another Thousand
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Old 30-12-2008, 16:03   #38
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RBEmerson:

Re the following, from your post, "AFAIK, it doesn't suffer from formatting or computation errors.", please clarify AFAIK for me. I assume this references the errors in H.O. 249, right?

Re Ageton's Method, I have it in Volume 2, the 1975 Bowditch, which was given to me. Older editions do get pricey, however as memory serves, I've seen mention of Ageton Method at amazon.com and or ebay.com .

If you ever get to Moorhead City North Carolina, there is a quite nice bookshop in a strip mall , East edge of town. I just found their business card. The name of the store is Bookshop. E-mail BOOKSHOP2@BIZEC.RR.COM. If this doesn't work, try lower case. Phone 252-240-1163. Fax 252-240-2522. I've seen some older editions of Bowditch there, and in October picked up a copy of Dutton's Navigation and Piloting. It was tagged at $14, I asked if the price was firm,and they said I could have it for $7. Sold. They usually have a few used books on navigation, ask should you get there. Just remembered, USPS booklet on Sight Reduction Methods contains what is described as Ageton Compact Table, runs 9 pages. Sounds like the Ageton Method.

Best wishes, and happy sailing.
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Old 31-12-2008, 00:10   #39
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AFAIK = as far as I know - TNX for the lead on Bookshop. Gotta dash!
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Old 31-12-2008, 06:13   #40
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BOWDITCH - The American Practical Navigator, 2002
NGA: NGA Publications - Bowditch

In addition to Bowditch, you can download HO 229 and HO 249 from the NGA web site here:
NGA Digital Navigation Publications

HO 249:
Index of /NAV_PUBS/SRTA/Pub249/

HO 229:

Index of /NAV_PUBS/SRTM/Pub229/
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Old 31-12-2008, 06:58   #41
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Gordo et al--

FYI, errors have been discovered in the on-line versions of the tables of HO 249 and, AFAIK, HO 229. The tables were supposedly going to be reissued, but whether that has been accomplished as yet remains in question. The matter is discussed at some length on the SSCA Forum. See SSCA Discussion Board :: View topic - HO 249 errors found in on-line edition

s/v HyLyte
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Old 01-01-2009, 09:49   #42
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HO 229 doesn't seem to be plagued with the same problems as 249. Here's a single file version of Bowditch. LINK The NGA version is broken down into one file per chapter (plus additional files) while this version is one big (40M) PDF with the PDF and document page numbering sorted out.
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Old 16-10-2011, 01:10   #43
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Re: Celestial Navigation Help Needed

hello,
i found this old post and i would like to know if there are some news about 'digital ho 249' tables,
is it possible to find a digital copy of this tables ??
free or to buy !!
i'm now crossing the atlantic on a yacht, the weather condition are exceptional and we are "playing" with the sextant.
we have internet on board but not the ho 249 tables
at the moment i'm using the tables provided in the Admiralty Nautical Almanac but i don't like this tables too much.

thanks for your advices
Roberto
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Old 16-10-2011, 01:44   #44
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Re: Celestial Navigation Help Needed

You can still download the HO 249 Air Tables from the following location:

Maritime Safety Information

This is a flaky way to link to pages, as it includes the session ID in the link, so it can break. If this doesn't work then just go to the link https://www1.nga.mil and drill down (this can take some time to find the tables). If the first link works then use the drop down menu to select the Air Tables.

As mentioned above there is a question of possible errors in the online edition, so don't rely solely on the results. It should be good for practicing.

Good luck, and fair winds

Greg
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Old 16-10-2011, 01:50   #45
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Re: Celestial Navigation Help Needed

Quote:
Originally Posted by roberto11 View Post
hello,
i found this old post and i would like to know if there are some news about 'digital ho 249' tables,
is it possible to find a digital copy of this tables ??
free or to buy !!
i'm now crossing the atlantic on a yacht, the weather condition are exceptional and we are "playing" with the sextant.
we have internet on board but not the ho 249 tables
at the moment i'm using the tables provided in the Admiralty Nautical Almanac but i don't like this tables too much.

thanks for your advices
Roberto

Go to the Pangolin website while you are in range. You can download Mike Harris' 30 day free trial of his 'Astro Calc' programme, with full explaination of the celestial nav theory, if you like it( I think it's sensational) you can purchase it for US$40.
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