At 1:52 I am not seeing where the Z value of 136.6 comes from. I get a number more like 78, regardless if I look in the tables or use a calculator. Other than that, you seem to have me on the right track. Thank you very much.
Got a crazy color coded plotting sheet for some stationary land sights using a bubble horizon and just the sun. Averaging them all up I've managed to use some geometric principals to yield a 3 mile accuracy in the middle of suburbia using the cheapest bble on the market
Hi Chris Amazing work you have been doing, I am just discovering it. A small technical question : when using the sun to check deviation, where did you get the 2 first figures on your paper : Declination 20.5 and latitude 18 ? Thanks
Hi Raphael, thanks for writing. I'm not sure if its covered in this specific video, but the source for that information is that declination comes from the nautical almanac for the given date and hour (declination is the "latitude" of the sun) and the latitude comes from the nearest 0.5 degree increment based on your dead reckoning or GPS position. These two figures are important to be able to use table 22 in Bowditch to solve the later problem. Thanks!
When working with LHA, you can subtract 360 degrees if necessary to make your math work out to less than 360. The tables only have LHA for 0-360, and sometimes you end up higher than 360 if, for example, your longitude and the GHA are larger. Thanks!
Excellent series. I needed a refresher as the last time I used astro was close to 30 years ago. This set of videos was clear and simple. Congratulations! This is by far the best I have found.
Thankyou so much for your time and effort put into producing these excellent training videos. I will dig out my oldish sextant and start as you suggest on the beach with a noon shot and then progress to a running fix moving between beaches.
I'm so sold. I was just considering to get a sextant, but after your video, I'm sure of it. It combines my two passions: sailing and stars. I will not get one for any useful purpose, but just for my enjoyment. Beats Sudoku any day.
Niklas Koskimies Hi Niklas, glad you are going to join the ranks of celestial navigators! I think that the plastic sextants are just as capable as the metal ones, especially for personal enjoyment and they are significantly less expensive; perfect for getting started in celestial navigation. Just be sure the telescope gives you a clear view...if you get a used sextant that is the area of most concern. Good luck!
This has been an excellent course from start to here. Thank you for making this easy to understand for the beginner. Looking forward to the rest of your courses. Thank you again.
I've gone through the entire video series and have rally enjoyed the way you have explained the practicality of these calculations. Thank you very much, Chris! but could you please explain the calculation of the meridian passage and how you got the 68º W for the Mer.Pas. time? The UPS should suffice, but is there a way to incorporate these plots onto a chart? thanks! Also to my understanding, the DR plot is directly from Lat. and Long. read off from a chart. the AP is the whole number we used to calculate 𝞕 and Hc right? And for the running fix all we plot is our latitude at local apparent noon, hence the 90º line, then advance using DST calculations
Hello Sir - Chris nolan i want to ask something should i also take into account to calculate for first and second estimate for latitide at meridian passage? or just take a DR on 1210 ZT based on given data COURSE 310T / SPEED 6 KTS and get result of DR Long 064 W. from the daily pages of almanac on "mer pass" is 1210 of( Long 60 W. - DR long 064 W.) = 4 Deg./14minutes Late. the actual meridian passage at DR Long 064 W. is 1224 ZT then that is the time should i take the actual sight on 1224ZT?
Hi Eric, that really depends on what you are trying to do...if you are passing an exam, I would recommend calculating the first and second estimates - but the exam will most likely tell you this. In order to do this, you need to dead reckon your position to the time of the first estimate, and then carry out the LAN sighting then. You could also do a great circle sailings calculation if the distance is large or your speed is fast like on a container ship. If you are not taking an exam and just out sailing, most people wouldn't bother with the first/second estimates because the level of accuracy doesn't matter as much. Thanks!
This series is amazing and taught me how to use a sextant! But I am going back to sea after having not used a sextant for a year and I need to be reminded of something... When we do (d inc x d) x 60 we are of course using the d inc found after correcting the declination found in the almanac with the corrected 'd' number, yes?
Hi Mark - I think we are speaking the same language, but just to put it another way, say the declination is 22 degrees 45 minutes. The "Dec Inc" is the 45 minutes. You account for the 22 degrees using HO229, but then need to just make another correction for the missing 45 minutes. You can do this using the front/back cover interpolation table, or the direct math. But I think you are on track. Good luck!
Thanks for this series. I started at the introductory series, and have gone right through. Just a bloke in the suburbs, who can now fix my position. I am just using a phone app for a sextant, and doing the sight reductions in a spreadsheet I made. Made my own plotting sheets with a drafting package. Been a fun and interesting journey. (Got inspired watching adrift with a 23 yo high school graduate navigate herself to Hawaii - truly inspiring)
Ah sweet series Chris, and Bowditch has to be one of the finest set of books ever printed. "Loved these vids!" I hope you have a break again soon to do more off shore sailing adventures.
I'm so sorry,but I cannot thank you for this explanation.You need to slow down,you are moving on like captain Speedy Gonzales.You need to have a method like captain Bob Glover.You need to slow down and explain the class better than that.
Hello, sorry you feel that way. Some people have success pausing the video as they go along. I prefer to move quick and have people pause than moving too slow for the majority. To each their own, thanks for watching. -Chris
Brilliant, thanks for sharing ! I'm a bit baffled by your plotting though. How are you keeping your bearings consistent while advancing LOPs, etc ? I've never seen it done that way.
Hi Blake, thanks for the question. I think what you are looking for is how I am doing "running fixes." In which case I have a video on that specific topic, but you can also find some more about it online using that search term. In essence, if you DR your position ahead, you can grab a previous sight and "advance" it to the new time and use it to cross bearings for a fix. It is not as accurate as a two or three body fix, but you can do it with stars or with terrestrial aids to navigation. Good luck!
Thanks for the reply ! I'm actually asking about your use of the course plotter around 7:28 to plot Z from AP2. I know how to plot bearings from a parallel or meridian, but how did you draw a parallel from it ? I understand that this is a very tangential question, but I'm very impressed by your use of the tool. Also, thank you for posting these videos. Great miniseries on gyro error, too !
It is Theory but sad it is not applicable in real life .. so I decided to make invention to solve that problem without any computation using a Clock... So I will need some 2 billion USD before I public it in British Council ... Thanks sir George Harrison to invent a clock for solve longitude problem so now I solve the Latitude problem using your same invention hahaha hahahahahah
Thanks Chris! These are great videos. Now I can finally get that Nav Brief done! It looks like you're having a good time out there. - Elvis
Yes, but I think the backup turn-bearing on your auxiliary trackline might be off by 125 yards…resubmit. :)
Very informative series! My request would be a series on sailing =]
At 1:52 I am not seeing where the Z value of 136.6 comes from. I get a number more like 78, regardless if I look in the tables or use a calculator. Other than that, you seem to have me on the right track. Thank you very much.
Never mind. I was looking at latitude same, not latitude contrary. Than ks again, this was a GREAT video. I appreciate the information-rich fast pace.
Got a crazy color coded plotting sheet for some stationary land sights using a bubble horizon and just the sun. Averaging them all up I've managed to use some geometric principals to yield a 3 mile accuracy in the middle of suburbia using the cheapest bble on the market
Nice Nick! Awesome when it works out for you! Be sure to practice morning and afternoon sights to capture the differences in the process :)
This video pulled it all together. Thank you!
Hi Chris
Amazing work you have been doing, I am just discovering it.
A small technical question : when using the sun to check deviation, where did you get the 2 first figures on your paper : Declination 20.5 and latitude 18 ?
Thanks
Hi Raphael, thanks for writing. I'm not sure if its covered in this specific video, but the source for that information is that declination comes from the nautical almanac for the given date and hour (declination is the "latitude" of the sun) and the latitude comes from the nearest 0.5 degree increment based on your dead reckoning or GPS position. These two figures are important to be able to use table 22 in Bowditch to solve the later problem. Thanks!
10:00
Timid
Virgin
Makes
Dull
Companion
thank you very much ^~^
why did you add 360 degrees to LHA on 1:33 ???
When working with LHA, you can subtract 360 degrees if necessary to make your math work out to less than 360. The tables only have LHA for 0-360, and sometimes you end up higher than 360 if, for example, your longitude and the GHA are larger. Thanks!
David Barrie #author 'enthralling' #book #Sextant The Halli Casser-Jayne show 5/28 3 pm ET #sailing #invention
bit.ly/U4EEMd
Excellent series. I needed a refresher as the last time I used astro was close to 30 years ago. This set of videos was clear and simple. Congratulations! This is by far the best I have found.
Thanks Thomas, I appreciate it.
Thankyou so much for your time and effort put into producing these excellent training videos. I will dig out my oldish sextant and start as you suggest on the beach with a noon shot and then progress to a running fix moving between beaches.
Good luck Alan!
Very informative...
Do you expect anyone to follow at that speed.
Hello, bottom right you can adjust the speed of playback on the video. Some people want it faster, some want it slower. All good!
Thank you for these videos. I finally understand Celestial Navigation
I'm so sold. I was just considering to get a sextant, but after your video, I'm sure of it. It combines my two passions: sailing and stars. I will not get one for any useful purpose, but just for my enjoyment. Beats Sudoku any day.
Niklas Koskimies Hi Niklas, glad you are going to join the ranks of celestial navigators! I think that the plastic sextants are just as capable as the metal ones, especially for personal enjoyment and they are significantly less expensive; perfect for getting started in celestial navigation. Just be sure the telescope gives you a clear view...if you get a used sextant that is the area of most concern. Good luck!
NavigationTraining Thanks.
This has been an excellent course from start to here. Thank you for making this easy to understand for the beginner. Looking forward to the rest of your courses. Thank you again.
You can probably make a dime or two by selling these videos on thumb drives for the bored/desperate sailor at sea.
I've gone through the entire video series and have rally enjoyed the way you have explained the practicality of these calculations. Thank you very much, Chris!
but could you please explain the calculation of the meridian passage and how you got the 68º W for the Mer.Pas. time?
The UPS should suffice, but is there a way to incorporate these plots onto a chart? thanks!
Also to my understanding, the DR plot is directly from Lat. and Long. read off from a chart. the AP is the whole number we used to calculate 𝞕 and Hc right?
And for the running fix all we plot is our latitude at local apparent noon, hence the 90º line, then advance using DST calculations
Just a tremendous series! Thanks so much!!
Hello Sir - Chris nolan i want to ask something
should i also take into account to calculate for first and second estimate for latitide at meridian passage? or just take a DR on 1210 ZT based on given data COURSE 310T / SPEED 6 KTS and get result of DR Long 064 W.
from the daily pages of almanac on "mer pass" is 1210 of( Long 60 W. - DR long 064 W.) = 4 Deg./14minutes Late.
the actual meridian passage at DR Long 064 W. is 1224 ZT
then that is the time should i take the actual sight on 1224ZT?
Hi Eric, that really depends on what you are trying to do...if you are passing an exam, I would recommend calculating the first and second estimates - but the exam will most likely tell you this. In order to do this, you need to dead reckon your position to the time of the first estimate, and then carry out the LAN sighting then. You could also do a great circle sailings calculation if the distance is large or your speed is fast like on a container ship. If you are not taking an exam and just out sailing, most people wouldn't bother with the first/second estimates because the level of accuracy doesn't matter as much. Thanks!
This series is amazing and taught me how to use a sextant!
But I am going back to sea after having not used a sextant for a year and I need to be reminded of something...
When we do (d inc x d) x 60 we are of course using the d inc found after correcting the declination found in the almanac with the corrected 'd' number, yes?
Hi Mark - I think we are speaking the same language, but just to put it another way, say the declination is 22 degrees 45 minutes. The "Dec Inc" is the 45 minutes. You account for the 22 degrees using HO229, but then need to just make another correction for the missing 45 minutes. You can do this using the front/back cover interpolation table, or the direct math. But I think you are on track. Good luck!
Thanks for this series. I started at the introductory series, and have gone right through. Just a bloke in the suburbs, who can now fix my position. I am just using a phone app for a sextant, and doing the sight reductions in a spreadsheet I made. Made my own plotting sheets with a drafting package. Been a fun and interesting journey. (Got inspired watching adrift with a 23 yo high school graduate navigate herself to Hawaii - truly inspiring)
Awesome Simon, congratulations!
IE when you can't get a cocked hat and need to work with acute angles
Very well done. Thanks.
hi chris! =) do you have videos in terrestrial navigation??? if you have,give me a link..thanks and God bless! =)
Chris your tutorials are really helpful keep up the good work
Thanks for the kind words, have a good day!
Very good! Thank you.
I am really enjoying your videos. They are done very well. Thank you!
Ah sweet series Chris, and Bowditch has to be one of the finest set of books ever printed. "Loved these vids!" I hope you have a break again soon to do more off shore sailing adventures.
I'm so sorry,but I cannot thank you for this explanation.You need to slow down,you are moving on like captain Speedy Gonzales.You need to have a method like captain Bob Glover.You need to slow down and explain the class better than that.
Hello, sorry you feel that way. Some people have success pausing the video as they go along. I prefer to move quick and have people pause than moving too slow for the majority. To each their own, thanks for watching. -Chris
Brilliant, thanks for sharing ! I'm a bit baffled by your plotting though. How are you keeping your bearings consistent while advancing LOPs, etc ? I've never seen it done that way.
Hi Blake, thanks for the question. I think what you are looking for is how I am doing "running fixes." In which case I have a video on that specific topic, but you can also find some more about it online using that search term. In essence, if you DR your position ahead, you can grab a previous sight and "advance" it to the new time and use it to cross bearings for a fix. It is not as accurate as a two or three body fix, but you can do it with stars or with terrestrial aids to navigation. Good luck!
Thanks for the reply ! I'm actually asking about your use of the course plotter around 7:28 to plot Z from AP2. I know how to plot bearings from a parallel or meridian, but how did you draw a parallel from it ? I understand that this is a very tangential question, but I'm very impressed by your use of the tool.
Also, thank you for posting these videos. Great miniseries on gyro error, too !
It is Theory but sad it is not applicable in real life .. so I decided to make invention to solve that problem without any computation using a Clock... So I will need some 2 billion USD before I public it in British Council ... Thanks sir George Harrison to invent a clock for solve longitude problem so now I solve the Latitude problem using your same invention hahaha hahahahahah
What are you talking about? What is not applicable in real life?
Hey Chris 🙋 any reason why we don't use intercept method for the morning sites instead it is preferable to use longitude by chron method?
Hello Ashu you can use the altitude intercept method for sights any time of day, thanks!