How To Calculate Compass Error by Azimuth of the Sun
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- เผยแพร่เมื่อ 21 ก.ค. 2024
- How To Calculate Compass Error by Azimuth of the Sun! A short video where I explain how to calculate a ships Gyro or Magnetic compass error from a bearing of the Sun by calculating the direction (or azimuth) of the Sun.
Ask any questions in the comments - I’ll do my best to answer them.
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Pro Forma: www.alistairbaillie.co.uk/blog...
NOTE: This video makes use of selected pages from the British Admiralty Nautical Almanac (Admiralty Publication NP314). The example uses the 2016 version of the publication so if you’re doing the calculation for a different year the numbers won’t be the same.
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Opening Tune: Good Starts by Jingle Punks
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#merchantNavy #navigationTraining - แนวปฏิบัติและการใช้ชีวิต
If you're getting the wrong answer when entering the formula into your calculator I've created a short video here which explains what you are probably doing wrong and how to fix it: th-cam.com/video/0YnFY4NGaR8/w-d-xo.html
How to get the gyro heading and magnetic heading? Hoping for your fast response. Good day
@@bienjunlukelacuna8984 The ships compasses.
@@AlistairBaillie it is given already in a problem to be solved?
Just promoted recently to 2nd officer and my brain gets rusty in the manual steps because i am using bridgeman app in my phone to compute gyro error every time i log in the Deck log book. Thank you so much for this sir...Now i am refreshed and can teach this confidently to my subordinates and cadets who someday wants to become an officer. This is crucial knowledge as an officer.
thanks very much for this. have my celnav exam a week on Wednesday and you've cleared up more problems than any of my lectuturers.
Amazing explanation. As younger Deck Officer I'm need to be fresh always to share this knowledge with the Deck cadets. Thanks you so much 🙌
Just wanted to say thank you for the videos. You helped me pass my license exam for a 3rd mate in the US. You're a saint and your videos are great learning tools.
Thanks!! Congratulations on passing and good luck in the future :)
Thank you so much. This Video is really good and easy to understand. Thank you.
thank you for sharing your knowledge sir,
Thank you very much for the explanation!!!! you explain things in a very pedagogical way.
Thanks - glad you found it useful
Did Help me a lot , thank you so much
First ever channel on youtube that has explained everything in very simple and easy way. Thanks a lot sir. Your videos are very helpful. Keep posting more :)
i hope you can make video on :
GMDSS Daily weekly monthly tests
noon report
Hi, sorry for the long delay in replying - GMDSS tests I shall certainly cover - however noon report is something that is company specific
Nice,video now my concept is clear...
Excellent presentation. I hope u will upload further video as series
Rahat Rumi way
Thanks you so much. I will be great ful if you please explain the usage of ecdis to find out variation, I some time have doubt whether its east or west , unlike paper charts where you know exactly that it's east or west. I have been using furono ecdis,please help.
When I put the coordination into the stellarium for the spesific time, the azimuth values are not matching. It shows 160 degrees instead of 277. Do you know why? I just started to learn.
I use the ABC formula and In the North sea the now, Lat was 57° and LHA was 002°, so when I Do A it comes out as 33.62S and B comes out as 8.98N C is 24.64S and thought it be wrong because numbers seem far too big but does that not matter due to my LHA being so small, true bearing comes out to 1 degree if bearing I took from the sun. So can A and B be larger numbers? I am normally seeing 0. Something normally.
Very clear and concise
Thank so much sir,but can i ask you why LHA is negative while i learned that from my school not negative at LHA sir
If the sun (or moon) is setting on the horizon, the calculated sextant altitude Hc = 0 degrees. If you put this value into the sight reduction formula for azimuth, Sin (0) = 0 and Cos(0) = 1, so the formula simplifies to the "amplitude" formula.
Awesome Video! Wondering how are you making this animation?
thank Sir so much.
Can you send me the Forma plz
thank you very much
TKS SO MUCH
can u explain how to calculate compass error by Norris table
I’ll add it to a future video
Hello, can anyone pls help me understand where and how he got the Variation in this one? I did not quite catch what he said in the video. I would appreciate it. Thanks!
Hi - Variation comes from the nautical chart or ecdis system for the ships position.
Thanks you so much , you are the god ! you beat all the internet shit publication that confuse people ! freaking nice job ! respect.
+Whisperin100 thanks!
Whisperin100 B
What do you do if your GHA + Long becomes more thhan 360 degrees. In my case it is 355 degrees + 021 degrees
If your LHA (GHA+Long) is greater than 360 degrees, subtract 360 degrees from it. If it's less than 0 degrees, add 360 degrees to it.
verified thru skymate. Thank you for the technique I've been using the Nories table before but when i see this and apply and check the nories table they are the same.
How do you write the equation into the calculator?
This various by calculator model.
Great video! Do you have to take the azimuth when the sun is setting or can you take it any time of day? Can you also do a video on the running fix method?
Thanks - Azimuth method can be used at any time that the body is visible. The theory behind a running fix for celestial calculations is explained as part of video 3 of my "How to Fix position from the Stars & Planets" located here th-cam.com/video/s2o8MFgIMac/w-d-xo.html using a plotting sheet. As for using running fix method with terestial objects, I will add that to my todo list for when I have time :)
@@AlistairBaillie thanks for your answer!!
Hi! I am confuse about to where you got the variation... we are still studying navigation and i want to know if we can get the variation by just using the coordinates and searching it up on a nautical almanac or the internet if it is not given on a quiz problem
The value of Magnetic Variation for a charted area is located inside any wind rose, in any nautical chart, for example, in the wind rose you could find a value expressed like this: 7º 34'W 2016 (4'W), where the value 7º 34'W 2016 is the magnetic variation in the area on the year 2016, and (4'W) is the yearly increment of the magnetic variation. What do you have to do is to correct the variation to the present year, for example, if the present year is 2020, you have to multiply (4'W) for the numbers of years from 2016 to 2020 = 4years, so (4'W) x 4 years = 16'W, then you have to, add the correction, if it has the same name of the variation, or subtract it, if it is named opposite, in this case, they have the same name W, so the variation for 2020 will be 7º 50'W. I hope this can help you to solve your doubt.
Hi - I'm afraid not - as @Gabriel Delgado says you have to look it up either on your paper chart or ECDIS system and then apply the correction for the present year. Some GPS units will also give you an approximation for your current position as well.
Dear Sir ıs it possible to explain why did you subtract the Az from 360 to find the true bearing? Yours sincerely
As the Azimuth was North West then the True Bearing is 360 - Azimuth - please see the explanation at 5:53 for the different quadrants.
Sorry Sir again
I found the Az= - 81.849
I don't know where I did mistake. So;
Sin 88 35,2 = 0.999 695
Cos 25 50,6 = 0.899 989
Tan 8 22,2 = 0.147 132
Sin 25 50,6 = 0.435 911
Cos 88 35,2 = 0.024 664
= - 0.999 695 / 0.132 417 - ( - 0.010 751)
= - 6.982 623
Az = - 81.849
@@ahmetkopuz3632 Hi, you have treated the result of "COS - LHA" as a negative when it should be positive, The COSine of -88.586666.... is a positive result. It is important that you do each step in the calculator as written in the formula otherwise you risk mixing up which sign the resultant answer should have when working with the SIN and COS curves.
You can't simply work out the SIN/COS and TAN for the value of LHA/LAT/DEC and then stick a -ve sign in front of it as the positive/negative applies to the original angle, not the result of the function.
I would like you to help me with this question Mr. Alistair,
1. what would happen with the correction of the declination if we supposed for the video example that declination for 22:00hrs (only for putting an example) was negative (-) 8º 21.9' South and the value for 23:00hrs (only for putting an example) was negative (-)8º 20.0 South, as is approaching to 0, should we consider this as increasing or decreasing to proceed after to add or subtract d correction?.
2. Negatives declinations are the same as south declinations? this because I noted in the nautical almanac that for the south the declinations are negatives.
Hi, If at 2200 it was negative 8-21.9 and at 2300 it was negative 8-20.0 then yes it is increasing as negative 8-20.0 is larger than negative 8-21.9, thus you would add the correction.
@@AlistairBaillie thank you very much! your explanations always are very helpful!!
Great video series by the way! Been binge watching your videos. Would like to know why the LHA is entered as a negative (-) in the formula. That's got me confused since the book shows that it is "sin LHA." And when i follow the book, i got the wrong answer. Thank you!
Hi, the formula I have presented here is intended to be used as a single entry into a calculator, yes you can do it in separate parts if you really want to but it's main benefit is the ability to be able to enter it all in one go and not have to worry about naming things correctly!
There is a version of the formula which uses LHA as a positive value, however if you are following that version of the formula you need to do your calculation in steps as you need to know if the bottom part of the fraction is -ve or +ve as you then subsequently name your azimuth North or South dependant on that.
However, if you use the formula presented in the video where you enter the LHA as a negative value then you don't need to worry about what value the bottom of the fraction is as your final answer will have the correct sign for naming.
I hope that description makes sense :)
@@AlistairBaillie thank you very much for answering my question! This totally cleared up my confusion.
Hi Sir! How did you come up with the formula?
It's a standard formula for calculating the azimuth.
Thought I can use a Math book though. Thank you so much Sir! The vid really helps a lot.
If I use ABC method result Az is 89.1
If I use this method on video result is -45.05
Please can you explain me why?
If your figures for Latitude, Declination and Local Hour Angle are the same as in the video, either you're entering into your calculator incorrectly or your calculator is working in Radians, instead of Degrees.
Yes me also i was checked my calculator
@@jemrifelianto2990 You will be entering the formula into your calculator incorrectly, make sure you have brackets in the correct place and are using the correct sign for each angle in the sin/cos function.
Awesome, except that I cannot write in the pro-forma. It would be interesting to make it edible and perhaps even auto-calculating.
Haha, some job for you too;)
Please Change the Text into Black Color, next time.. Thanks..