Celestial Navigation: Nautical Almanac

[SeppSF]

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

[AdamLein]

Originally Posted by SeppSF

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.

[sailjunkie]

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.

[AdamLein]

Originally Posted by sailjunkie

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.

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.

[sailjunkie]

Adam, places where CN makes sense means warmer climes than PNW. That makes 2 of us!

[AdamLein]

Originally Posted by sailjunkie

Adam, places where CN makes sense means warmer climes than PNW. That makes 2 of us!

Everything makes more sense in the tropics

[milutin]

hello there....


i am learning CN and found something confusing

ie. Hc -0.57' and Ho is 43deg 38'.2 i do not know what to do in this case. i could not find any answer searching internet. even there is not in this book "celestial navigation" from tom cunliffe that i have. i know that i have to substract Hc from Ho if Hc is less (to) or Ho from Hc if Hc is bigger (from). but that is only case if Hc or Ho are close (near) in few ' (miles)
i know when i have, let say Hc43deg 15' that i have to substract from Ho 43deg 38'.2 to get 23.2M To.

but if i have Hc -0.57'
+ d(47) 10
------------
Hc 01deg07

and Ho 43deg 38'.2 now what ???? i can not just substract Hc from Ho

there is Hc -1, -4, -6, 00.35 i can not substract it from, let say Ho 43deg 23'.5. i can but i would get Ho 43deg and something. is it that to much miles to or from to intercept

thank you for your help

[AdamLein]

Originally Posted by milutin

hello there....

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?

[Brent Swain]

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.

[AdamLein]

Brent, if he's got a computed altitude, he probably isn't doing a noon sight.