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Old 20-12-2010, 09:03   #1
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Celestial 229 vs 'Calculator Method' ?

With a good scientific calculator, it seems to me dispensing with the tables is preferable - but I am in the middle of my (self-taught) education on the subject.

Is there any reason I would want to instead use the pub 229 tables (or 249, for that matter)?
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Old 20-12-2010, 09:10   #2
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Lots of options here.

I always carry printed sight reduction tables in addition to calculator and computer methods. I favor HO214, but lotsa folks like HO229 and HO249.

You could use a scientific calculator, but a dedicated navigation calculator would be somewhat easier. You can often find these on eBay for reasonable prices.

Or, you could use a programmable calculator and enter the programs yourself, as I do with the HP-42S.

For computer sight reduction there are several programs available. I still use PC Navigator...an old DOS program which still delivers for me and runs on most any platform

Bill
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Old 20-12-2010, 21:13   #3
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You're right, a good scientific calculator is better because you can use your actual assumed position for multiple sights. Using tables you probably noticed that the assumed position needs to be adjusted for each sight to be an even table entry, so it can result in a confusing and sloppy plotting sheet. After you memorize the formulas for the terrestrial and astronomical triangles, then you can key it into the calculator faster than looking it up in the sight reduction tables and the plotting is easier.

Of course a programmable calculator would be even easier, but I understand that was not the intent of your question, and of course you would want to take a hard copy of the tables.
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Old 21-12-2010, 05:00   #4
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The primary advantage of tables is that one never needs worry about batteries. I have been using a "Merlin II" navigation computer--actually a nicely programed Sharp PC-1248--for reducing sights since the late '80's. It's an excellant machine. But, it does rely on batteries and I have had the experience of loosing the program when changing batteries by not moving quickly enough. With HO 229 and a current Almanac I was good to go anyway. We added a GPS in the early '90's but there is still something gratifying about moring and evening stars and noon lats, eh?

FWIW...
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Old 21-12-2010, 16:29   #5
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<< never needs worry about batteries >>

Yes, that is a big concern, and a good reason to use a non-programable calculator, since they are available in solar powered.
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Old 24-12-2010, 13:52   #6
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Calculator batteries can be problematic, but if you use an old Palm PDA there's good reduction software available for them, and AAA cells can usually be stolen from something else if you have no dedicated spares. Or, ship's power used to recharge the newer ones, i.e. Palm Treo's.
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Old 24-12-2010, 15:24   #7
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G'Day all,

Way back when I learned on HO249... no batteries, but I found that when at sea using the tables would induce mal de mer in short order. Something about trying to follow those rows and columns of figures whilst bouncing about (on a 30 ft S&S). So I went to a calculator to do the trig. Worked well for me. Then got a HP41 with a Nav Pak and dispensed with the Almanac... even better! Then found the above mentioned DOS PC Nav and thought I'd died and gone to heaven !! It has the advantage of error analysis and averaging multiple sights and built-in star finder... all fits on a floppy disc, too!

So, these days we carry a sextant, an old Almanac with the corrections tables for updating and the various calculators and software... and the usual lot of GPS's. I hope that in the event of catastrophic GPS failure I could find all the other stuff before we ran into something! I know it's down there somewhere...

Cheers,

Jim and Ann s/v Insatiable II lying Towlers Bay NSW Oz
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Old 12-02-2011, 12:22   #8
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I have a Merllin 2 navigation computer that I have not used in many years but it has been reprogrammed by Mike Pepperday now I find I do not have the operation manuel and only have the quick reference sheet which does not explain how the entries are made. Does anyone have a Manuel or can anyone email me with instructions.
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Old 12-02-2011, 14:02   #9
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think it's based on the Sharp EL-512/Merlin calculator.......try the sharp web site
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Old 12-02-2011, 14:22   #10
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Has anyone used the app. Celestial by Navimatics? It looks like a celestial navigation app. for the Iphone, I was wondering if anyone has had any practical experience with this item?
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Old 12-02-2011, 16:49   #11
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Quote:
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think it's based on the Sharp EL-512/Merlin calculator.......try the sharp web site
thanks for the reply.
Yes it is the Sharp EL-512 Merlin and I have their instruction book for the computer but that doesn't help me with the Navigator program on how and where to enter the nessarry time and altitude numbers. The computer origional came with instructions for the Navigator program and I need to find a copy of it our get instructions from someone who knows the necessary steps.
Thanks again
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Old 12-02-2011, 20:09   #12
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PC Nav software

Hopefully in the spirit of the OP's question, the PC Nav software sounds like it would be just the ticket but where might one find it? Did a google search and nothing in the first couple of pages. Any idea where one might beg, borrow or buy (kind of draw the line at steal) this program?

Thanks
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Old 12-02-2011, 21:42   #13
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Quote:
Originally Posted by sneuman View Post
With a good scientific calculator, it seems to me dispensing with the tables is preferable - but I am in the middle of my (self-taught) education on the subject.

Is there any reason I would want to instead use the pub 229 tables (or 249, for that matter)?
There's no mathematical advantage to using the tables. In 249 you're doing double interpolations, no interpolations on a calculator. I brought copies of the relevant tables in case of calculator failure.

John
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Old 12-02-2011, 23:26   #14
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I've used the tables so far, but an antique Tamiya nav calculator came into my possession and it seems to work perfectly (on 4 AAs which it merrily eats, mind you, like my old handheld GPSes).

So I should try to use the thing. It is too old to predict star positions, but is perfectly able to work out the trig.
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Old 14-02-2011, 14:14   #15
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Redirect to Skipmacs post

I also would like some input on PC programs for CN.

Anybody using their laptop to calculate position?
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