Getting Started in Celestial Navigation (The North Star)
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- Опубликовано: 28 сен 2024
- This video is part 4 (and final) of the "Getting Started in Celestial Navigation" video series.
Part 4 of "Getting Started in Celestial Navigation," (The Pole Star) describes the process of finding, measuring, and reducing sights of Polaris (The North Star) to determine latitude at night in the northern hemisphere. Additionally, it talks about creating Universal Plotting Sheets for celestial fixes.
Here are some additional resources pertaining to this lesson:
Wikipedia (Polaris): en.wikipedia.or...
Where to buy the Universal Plotting Sheet (UPS): www.weems-plath...
Detailed instructions on how to build a UPS. From "The Bridge Refresher Guidebook," guest authored by Captain Rich Asaro. www.scribd.com/...
Navigation Materials
All example problems in this course use the 1981 Training Nautical Almanac and HO229 (there are three example problems in this lesson).
1. The 1981 Nautical Almanac
Hardcopy 1981 Training Nautical Almanac - www.amazon.com/...
Note you can also download for free or minimal price online by searching google, for example ebookpie.com/e.... You can download it from lapware.com if you pay the monthly fee for access. Sidenote - lapware is an amazing training tool!
2. HO229 - Sight Reduction Tables for Marine Navigation
Free download - msi.nga.mil/NGA...
3. Other materials of use
Free download of Bowditch (The American Practical Navigator) - msi.nga.mil/NGA...
USCG licensing website. This contains all the possible questions on USCG exams - www.uscg.mil/nm...
The book I used to learn celestial navigation myself, and I think one of the best celestial navigation books out there, is "Common Sense Celestial Navigation" by Hewitt Schlereth - www.amazon.com/...
Produced and presented by Christopher D. Nolan, USCG cutterman (8 years) and US merchant mariner (500 ton Oceans). Currently on sabbatical aboard S/V Navigator.
Great video series! I've never seen plotting longitude explained so well and the practice examples helped tie everything together.
Thanks to your videos i passed all the celestial navigations exams at Naval Academy of Uruguay!! Thank you very much, you were very very helpful.
Thanks Samuel, great to hear you are going for the license, and thanks for the feedback! The next series should be out just around Christmas (we're on holiday for hurricane season). If you are looking for some help with the navigation general or celestial exams, check out our scribd.com page which is referenced on the maine youtube channel page (click "about") It solves almost every type of problem you will see on the exam, depending on the scale of license you are after. Good luck!
Really quite a nice series. Very professionally done and ' hope that you keep it up. I learned a great deal and greatly appreciate it.
Excellent series. You clearly know your stuff and explain it very well indeed ; best I've seen. I'll have to go over the films again to drum it in! Incidentally, I was moored between the Pitons at the same spot as you, in February! Nice place to be. I await next series.
I like how you do everything free hand and not on standard CN worksheets.
Google's Gemini A.I. recommended me this video,
As i am talking about universe and solar system
Thanks for the nice comments guys! We're writing the next episodes now, and we'll be back on the boat in December filming the next series. The next series will be called "Going Further in Celestial Navigation" and will talk about using the Sun at anytime during the day for a line of position. After that, we'll be working on "Advanced Concepts in Celestial Navigation" with lots of other cool stuff. If there is something in particular you'd like, let us know! Happy Navigating!
What's the name of the song from 6:52?
Do you have a recommendation for any worksheets that have the process laid out (for sun and stars), so the data can be filled in as the problem is worked? I have seen some online at different suppliers and was wondering if you had any experience with these.
Dennis Annotti Hi Dennis - indeed, what you are referring to are "strip forms" which allow you to fill in data as a calculation progresses. I am of two minds on these.
First - if it works for you - do it. Anything online (free) will be perfectly acceptable as long as you internalize the process and make it your own. Additionally, there are forms in Bowditch and in the Nautical Almanac you can copy for yourself.
Second - I generally advise not using them to start out with. The reason for this is I've seen many people get hung up in trying to remember what "Hc" is, or how to calculate "Along." Most of the abbreviations on the strip forms are intended to remind experienced people what they are looking for. As beginners, it can be more trouble than it is worth. So - I recommend, in essence, creating your own strip forms. As you move from sight to sight, and from day to day, you'll find that you do the problems the same way each time, and your log book can serve as a reminder of what you might need to look for next (if you forget).
So bottom line is that the strip forms are definitely useful. However, depending on your learning style, it might be advantageous to work without them, at least in the beginning. But as long as you can find your position - whatever works, works!
Good question and good luck! - Chris
Great series, and very clear. But I have a question. In example 1, where the date is 10/25/18, you show (at about 4:24 into the video) that the LHA Aries is 8 degrees. I thought the LHA Aries was 68 degrees. What am I missing?
Hi, 4 years late, I know.
The appropriate column covers a range from 60 to 69°. However, the LHA of Aries was determined to be 68° That's why Chris moved his finger from the "8" in the left most column to the 60-69° column. Hence the A0 correction being 18.5 minutes.
I should have said at the ned of my last posting, Is Polaris int the sand diagram, or is that not the point?
What about if you dont have an almanac. Like Magellan, deleon, and such back in the 15th century? What did they do for lat and long? Thats how i wanna learn
Hi Natas, good question. One way sailors such as that could have used the sun and Polaris altitudes to determine latitude very roughly by creating pre-cut sticks or notches in their masts (the vikings did this) to measure altitude at noon/polaris. From there, they could determine if they were north or south of their destination and adjust accordingly. Before longitude, navigating was hard!
Latitude and dead reckoning along a line of latitude was the best they could do. hence the need to come up with a means of determining longjtude which was a huge ask
You're cool.
I have heard and read comments that celestial navigation is "simple" and can be learned in a couple of days. After beginning to study this stuff I have to conclude that these comments are bullshit. Learning this stuff is doable but is not "simple", nor can it be learned in a couple of days. Getting these skills to a point of being able to bet your life on it takes study and practice; a lot of study and practice. I enjoy watching many of the sailing videos where the navigation is done strictly by electronic navigation (GPS) devices. The comment they always make is "this is how it is done now". I have a drawer full of GPS devices purchased over the last 20 years that no longer work. I always wonder, do these people know how to navigate when they are in the middle of the ocean and their GPS stops working? The videos show no reference to the people on these boats using a sextant and a nautical almanac. They simply buy a sailboat and take off.
david
End, not ned. I must be tired.
lol "is that how this is going to go today?" Crack up
These are great! I've been watching them over and over and taking notes. Thanks for posting
a real navigator pronounces Cassiopeia like you do!
Thank you for watching and for commenting again on the accuracy of the calculations in the videos. As this is an intro course, minor factors are often rounded or simplified in order to focus on the concept of the problem. Especially with Polaris, a dim star, it is difficult enough to sight the object more accurately with a standard sextant then 2 miles. Simplifying the process as much as possible enables accurate and useful celestial LOPs with minimal poss. of major math errors. Tks again.
Sir, I heard that the horizontal lines are called latitude. But I am confused, here when u drew a horizontal line and u called it as longitude.. please help me sir
My Nautical Almanac does not have a separate page for Polaris, but it does list the SHA for Polaris and its declination for any day. Am I correct to assume the three corrections you go through here are factored into the SHA and declination?
no answer
thank you so much!!! i learned a lot!!!
Great - thank you for watching. I'll be off the boat for the summer, but the next series will be posted starting in December....sorry for the delay:)
nice video
Quite a nice spot! I hope to get back there on the way north, but the trades will decide for us. Thanks for watching and sail safe!
Stars appear to rotate around polaris? thats odd, i would imagine alot of parralax happening due to rotation of earth and we orbit the sun.
very little parallax because the stars are so far away
Just learning how to use a sextant and do basic plotting. This is a really wonderful & practical CN "get-started" series! Your visuals & math problems really bring it all together. BRAVO!! Thank you so much. Already looking forward to your next series. Stay safe.
This series has helped on my classes for captains licenses, hoping to see next 'Going Further in Celestial Navigation'
Please do use graphics, it makes the "visualization" easier
Thanks
Good day! why do we need to have a DR position? I mean it's an observation at night and it is very difficult, sometimes to get a good sight and good sights might come within a just a minute or two, aren't you just going to use or GPS position?
This just what I've been looking for. I read and read and get lost in the terminology but you explain it visually and it all make sense! Thank you.
how to write on the navigation like the sun longitude or sometin
Oh ya the Plotting Sheets, 1 NM cockedhat is not bad
If I'm understanding correctly, just sighting Polaris is fairly close to our latitude, but not close enough. Then we make usual IC, DIP,and Main corrections to get even closer to the true latitude. Then we leave that and start focusing on Aries which I think is your rock on the left side of your sand diagram, and we, I believe, are the leaf in the center, to the left of the Greenwich twig"X"). We look up the GHA of Aires in the tables and subtract our guesstimate dead reckoning longitude to come up with a approximate LHA of Aries. That gives us the ability to go to the tables to look up a0, a1, and a2 correction factors that corrects our latitude even further.
My question is, what does doing the calculations above with Aires have to do with Polaris and refining our latitude further? Is Aires in that sand diagram or that's not the point?
Thanks much,
Rob
Hi Rob, pretty much - I use the rock as "any celestial body" to teach the point of LHA, local hour angle.
In any case for Polaris: yes - correct the sextant reading for dip, IC, Main. Set that aside for now.
Then, near the back of the Nautical Almanac are the Polaris Tables. It is page 274 in my version, but kind of buried in the appendices, just look around for it and you will find it. You enter this table with the LHA of Aries. So in order to get LHA of Aries, you need to use the daily pages. Pull out the GHA of Aries, either add (east) or subtract (west) your approximate longitude and you now have LHA of Aries.
Now the Polaris tables should guide you the rest of the way (month, DR latitude corrections).
If you would like a written guide, you can download one for free at www.scribd.com/doc/141193600/Part-12-Polaris-Problems. It is written for expert-level calculations for academic exams, but you should be able to use it to help get the process down.
Hope that helps!
Great help
Great work . A very good series , you've put in a lot of effort . Thanks
Thanks a lot!
How do you calculate your longitude?
Hi Bryan, latitude at LAN and by Polaris are special cases - in order to calculate longitude, see the next video series "Going Further in Celestial Navigation." You'll get to work more thoroughly with the sun in those videos. Thanks!
Pls how can I use the sextant to take star sight when it dark, how can I see the horizon in the night.
Hi Stephen, thats the big challenge! You will need to have a clear horizon - so the best times to observe the stars is dusk and dawn.
Hello sir, as far as I know they don't actually star sight during night time. You can star sight during sunset and sunrise.
during sunset it very hard to see a star and during sunrise it very hard to take star sight..... I mean practically....
The best times for measuring stars are shortly after sunset, and shortly before sunrise. You will need to see a clear horizon and the star at the same time. Sometimes this can occur all night long, depending on the moon's position in the sky, but most often star measurements are taken shortly after sunset and shortly before sunrise. Look into the southwest tonight after sunset and you will start to see some bright objects in the sky that you could use to navigate by. Venus and Mars are both low in the southwest. Good luck!
Thanks
Hi,there is one thing i dont understand on the Example 2 the LAT final calculation should be 25deg 26.9???
maybe i was wrong.....
ALL those films are awsome!!!
thank you very much
How abouy the sun?? Please
Hello Konten, this video is part of a series, and the sun is covered in another video. Thanks!
@@NavigationTraining , yes yes ,thnkyou sir, thnkyou, i can't wait 😊😊😊🙏🙏🙏,.
I'm a merchant marine cadet
OK I must have missed something, because in calculating longitude, it seemed that after all the minute corrections, the final answer for LHA was obtained by subtracting our Dead Reckoning estimate, which could be way off and would therefore introduce error. Can you explain where I went off the rails on this?
Oh, and the music is too loud. We don't need to hear the same notes for the entire videos. Thanks, this has been very helpful.