I was in the last class to have the old celestial navigation class. It's not a difficult thing to do. You take a measurement with a sextant then consult a fifty pound book full of tables, get the two closest numbers to what you want and interpolate. There are various techniques based on time of day and the stars you can see, but if you're not doing it regularly you're going to have to look up the procedure anyway. An…
Naval Academy reinstates celestial navigation
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Re: Naval Academy reinstates celestial navigation
#32I was in the last class to have the old celestial navigation class. It's not a difficult thing to do. You take a measurement with a sextant then consult a fifty pound book full of tables, get the two closest numbers to what you want and interpolate. There are various techniques based on time of day and the stars you can see, but if you're not doing it regularly you're going to have to look up the procedure anyway. An…
I'd rather give each sailor a course in the kind of math and programming needed to create the tables.
The Naval Academy absolutely does train thousands of naval officers in this kind of math and programming. For the most part, they will apply those skills to more difficult problems, but if those tables had to be recreated, you would have no difficulty finding an Academy officer who could do it.
The Academy doesn't train the "sailors", though, just an elite corps of officers, and you don't need to have everyone on board making his own book, just have a few specially trained people (on land, presumably) who could if they needed to. They Academy makes sure many such people exist.
Re: Naval Academy reinstates celestial navigation
#33Earlier quoted context omitted.
Do you mean latitude? I remember the days being longer in the summer when I lived at higher latitudes, but I'm having trouble seeing how you could calculate longitude by looking at sunrise/sunset.
Thanks stan_rogers and splat, using local noon plus a clock makes total sense after you described how it works. And I just read a fun Wikipedia node on the history of longitude for good measure too. https://en.wikipedia.org/wiki/History_of_longitude
There is an excellent book about "the Longitude problem" that details John Harrison and the invention of high precision chronometers: http://www.amazon.com/Longitude-Genius-Greatest-Scientific-P... Great short book for any engineer.
Re: Naval Academy reinstates celestial navigation
#34Earlier quoted context omitted.
We might have computers, but GPS signals can be spoofed: https://en.wikipedia.org/wiki/Spoofing_attack#GPS_Spoofing
Is there a reason why the signals aren't digitally signed? I understand that GPS and GLONASS was deployed over 30 years ago, but surely Galileo, with its first satellite launched 4 years ago can have this?
GPS signals are weak. You simply jam them.
Re: Naval Academy reinstates celestial navigation
#35I was in the last class to have the old celestial navigation class. It's not a difficult thing to do. You take a measurement with a sextant then consult a fifty pound book full of tables, get the two closest numbers to what you want and interpolate. There are various techniques based on time of day and the stars you can see, but if you're not doing it regularly you're going to have to look up the procedure anyway. An…
Celestial Navigation was a part of USAF navigator training, but was retired about the same time as the USN - and it should remain that way. The USN's reinstatement of CN is a signal that the Navy does not understand it's own technology and threats(cyber attacks). And just common sense says a ship operating off CN will not be able to bring kinetic effects to the fight. The article mentions CN oriented a disabled Apollo 12? Gimme a break, what saved the mission was the quick wit of the engineering staff... and a crew that understood its own technology.
Re: Naval Academy reinstates celestial navigation
#36Earlier quoted context omitted.
If the people on a modern naval ship don't have access to some kind of basic computer, then they have bigger problems than navigation.
A total blackout has happened to a US Navy Ship in recent memory: https://en.wikipedia.org/wiki/USS_Yorktown_(CG-48)#Smart_shi...
And when that happened, they had a bigger problem than navigation.
Re: Naval Academy reinstates celestial navigation
#37I was in the last class to have the old celestial navigation class. It's not a difficult thing to do. You take a measurement with a sextant then consult a fifty pound book full of tables, get the two closest numbers to what you want and interpolate. There are various techniques based on time of day and the stars you can see, but if you're not doing it regularly you're going to have to look up the procedure anyway. An…
> It's defeated by cloud cover and fog.
Only on Earth we used it as one of the navigation systems to get astronauts on the moon.
Re: Naval Academy reinstates celestial navigation
#38I must be the last person ever who survived thanx to sextant in 1990:
I had $50 plastic sextant "Ebco". I made a program in my pocket computer (Atari Portfolio) which automatically showed your position on a map (A line perpendicular to the sun, ie with several measurements you could get a total fix). Realized however that sextant is useless if there is no horizon visible in direction of the sun. I needed "artificial horizon" but it was $1000. Too expensive. Then I saw the movie about Nansen crossing the Greenland. All he had was a bottle of mercury. He simply measured the angle between the sun and its reflection. I felt soo stupid.
Then I started paddling from Vancouver city to the west in 1990. I did not understand them tides. I did not know you can get pretabulated tables. I was paddling against tides most of the time. Somewhere between Kelsey Bay and Telegraph Cove there was 2 weeks period of fog and rain. I totally lost it. I was running out of food. I decided to turn back to Kelsey. But then the setting sun peaked out and I was able get my longitude. I was 3 kilometers from Telegraph cove. Paddling back would have been a suicide.
About 80 km between those places. But I was doing it against tides averaging less than 10 km per day.
BTW. George Vancouver was also stuck for weeks at the same stretch of Johnstone Strait. The devilish tide current appeared to be totally random and followed none of the god-given rules and laws.
https://www.flickr.com/photos/timonoko/9513772987/in/album-7...