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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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  #11  
Old 04-20-2010
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I know. I have an Aristo. I had a life raft use case in mind. Really no electronics involved.

Here a picture of it:
http://sliderule.ozmanor.com/rules/i...ront-right.jpg
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  #12  
Old 04-20-2010
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Quote:
Originally Posted by SeppSF View Post
I know. I have an Aristo. I had a life raft use case in mind. Really no electronics involved.

Here a picture of it:
http://sliderule.ozmanor.com/rules/i...ront-right.jpg
Very nice. I use a Pickett ES-800:

http://sliderule.ozmanor.com/rules/i...front-left.jpg

Except mine has red numbers on the reverse scales and slightly different end pieces and indicator.

Do you know of any tricks to solve the navigational triangle with a slide rule? In particular in cases where the trig scales lose precision, like for sines near 90.
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  #13  
Old 04-20-2010
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If this is a bit off-topic then I apologize in advance.

If one is going off-shore, then I can definitely see why mastering celestial navigation is a VERY good idea.

However, for coastal cruising in the PNW, piloting skills are a must. CPS and Cdn. Yachting Assn both offer excellent courses.

While I remain fascinated by celestial navigation, it is usually too cloudy here in the rain forest.
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  #14  
Old 04-21-2010
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Quote:
Originally Posted by sailjunkie View Post
However, for coastal cruising in the PNW, piloting skills are a must.
Totally agree. I don't expect to ever resort to CN in our local waters. If I really didn't know where I was, landmarks, bottom contours, and other sources of information from coastal piloting are much more useful and timely.

However, I would like to cruise some day in places where CN skills make sense, so I might as well practice now.

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While I remain fascinated by celestial navigation, it is usually too cloudy here in the rain forest.
I've been surprised at how often I could get good sights. The right combination of filters often punches through clouds that obscure or blur the sun to the naked eye. Overcast, rainy skies are basically hopeless, but if the sky has patches of bright cloud and dark cloud, the bright spots are often transparent under filters and a crisp solar disc can be seen through them.
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Old 04-21-2010
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Adam, places where CN makes sense means warmer climes than PNW. That makes 2 of us!
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Old 04-21-2010
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Originally Posted by sailjunkie View Post
Adam, places where CN makes sense means warmer climes than PNW. That makes 2 of us!
Everything makes more sense in the tropics
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Old 04-02-2012
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Re: Celestial Navigation: Nautical Almanac

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Originally Posted by milutin View Post
hello there....
Quote:
Hc -0.57' and Ho is 43deg 38'.2
Sounds like something went wrong when you did the computations. Can you give all the details?

One possibility is that you used an assumed position very far from your actual position. Another is that you used Pub 249 incorrectly, which is very understandable as I mess it up all the time. Make sure you use the correct table, including same name vs. contrary name.

So, what's your AP, what star, and what time of observation?
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Old 04-02-2012
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Re: Celestial Navigation: Nautical Almanac

For sun sights , almanacs repeat themselves every 4 years. So get 4 years in a row and you have all the backup you need for sun sights. Even one several years out of date is only about three miles out on sun sights.
I can tell people how to take a noon sight in about 5 minutes.
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Re: Celestial Navigation: Nautical Almanac

Brent, if he's got a computed altitude, he probably isn't doing a noon sight.
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Re: Celestial Navigation: Nautical Almanac

Nice. That's what practice is for.

By the way, if Procyon's computed LHA is 358°58.4' then I think it makes more sense to round up to 359° for the purpose of indexing Pub 249, no? That means you should use the row above.

Also, you need to interpolate between 5° and 6° of declination. If your computed declination has 11.4' attached, and d = 60', then you need to add 11.4' to Hc, which brings you up to Hc = 43°11.4'. This is a lot closer to your Ho of 42°38.2'.
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