
Naval Academy reinstates celestial navigation - aoldoni
http://www.navytimes.com/story/military/tech/2015/11/01/naval-academy-reinstates-celestial-navigation/74998554/
======
drblast
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.

And although you might not always be able to rely on GPS, inertial navigation,
dead reckoning, and visual navigation using landmarks, celestial navigation
has a huge drawback.

It's defeated by cloud cover and fog.

~~~
Retric
Not to be overly pedantic, but if you have an accurate timepiece you can get
your longitude from averaging sunrise and sunset times. It's not particularly
accurate, if you can't see the sun, but could be useful if you where otherwise
lost at sea and under total cloud cover for a long period of time.

~~~
nocarrier
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.

~~~
nocarrier
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](https://en.wikipedia.org/wiki/History_of_longitude)

~~~
aguynamedben
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...](http://www.amazon.com/Longitude-Genius-Greatest-Scientific-
Problem/dp/080271529X) Great short book for any engineer.

------
usrusr
Three hours of training? Either celestial navigation is much easier than i
think it is or this is exactly the sort of compromise mothers should warn
their children about. I'd rather sail into a GPS outage with a one in ten
chance of having a navigator trained 30 hours on board than with a 100% chance
of having one trained three. And it gets better when you consider crews larger
than one. Sure, we all know that decision making isn't easy, but that should
not be an excuse to get away with a compromise like that.

~~~
SamReidHughes
Celestial navigation is way easier than you think it is. We have accurate
clocks now, and you can just take the measurements and feed it into the
computer.

~~~
toyg
The point of this training today, I would expect, is that computers might not
always be there.

~~~
knodi123
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.

~~~
showerst
A total blackout has happened to a US Navy Ship in recent memory:
[https://en.wikipedia.org/wiki/USS_Yorktown_(CG-48)#Smart_shi...](https://en.wikipedia.org/wiki/USS_Yorktown_\(CG-48\)#Smart_ship_testbed)

~~~
knodi123
And when that happened, they had a bigger problem than navigation.

------
privong
This topic, though a different article, received a fair bit of discussion a
month ago:

[https://news.ycombinator.com/item?id=10385244](https://news.ycombinator.com/item?id=10385244)

------
ams6110
Why not instead a "modern" digital sextant consisting of a digital camera and
software. Still enables navigation by the stars (or sun) as a backup to GPS
without having to spend thousands of man-hours training cadets to do it
manually. And while not as accurate as GPS certainly, it would most likely be
better than or at least equal to the best human navigators.

You'd harden the system against EMP which is probably a standard requirement
of military electronics anyway (I'd hope...)

------
engi_nerd
Even if you don't encounter an enemy attack that disables GPS (which is not
difficult), you (meaning anyone concerned with national security) should still
be prepared for navigation by alternate methods when you consider how often
equipment malfunctions can cause self-jamming of GPS. It's happened to me on
systems that I support.

------
douche
Interesting. I've been reading the Aubrey-Maturin series by Patrick O'Brian,
and besides looking up what in the world spotted-dog, calipash, staysails, the
various and sundry varieties of vessels, or a Magellan jacket are, there's a
fair amount of old-time celestial navigation throughout - the constantly
documented daily ritual aboard ship is punctuated by the daily observation of
noon, and comments on the nutation(?) of the planets... It's pretty amazing
how well people were able to fix their positions with such primitive
instruments.

I can pick out the Big Dipper at night, and figure out if I'm going east or
west by the sun during the day, but that's pretty much the extent of it. I've
never been out in the open sea, where I imagine you can actually see the stars
well - the day-glo murk from the omnipresent streetlights blots out most of
them if you are anywhere near civilization.

------
timonoko
I 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...](https://www.flickr.com/photos/timonoko/9513772987/in/album-72157634483451516/)

------
bawana
We will be seeing more of this kind of stuff as the world gets more
complicated. Obviously, there are not enough people who know how to
troubleshoot computer networks, debug poorly written legacy code and simply
maintain the complex realtime systems that are used to automate buildings,
boats and planes. I can imagine pilots will continue to be required on planes
for this reason even though planes largely can fly themselves. Same thing with
reading topo maps - a skill that all infantry will continue to need even
though they have gps. In a sense, this is insurance needed to protect us from
"the ghosts of Luddites'.

------
nateberkopec
There's a reason certain ICBMs, like Trinity, still use celestial navigation.
GPS can be disabled - but the stars aren't going anywhere.

------
remarkEon
If anyone has read "Ghost Fleet", this seems appropriate. However, I tend to
agree with usrusr about the seemingly shallow depth of the course.

[http://www.amazon.com/Ghost-Fleet-Novel-Next-
World/dp/054414...](http://www.amazon.com/Ghost-Fleet-Novel-Next-
World/dp/0544142845)

------
dabernathy89
> The same techniques guided ancient Polynesians in the open Pacific and led
> Sir Ernest Shackleton to remote Antarctica, then oriented astronauts when
> the Apollo 12 was disabled by lightning, the techniques of celestial
> navigation.

You'd think the proof reader would at least catch an issue in the very first
sentence.

------
mark_l_watson
Very cool.

Back in the 1970s I owned a sextant that I kept on my sailboat but I don't
remember how to use one anymore. GPS is great but old skills like celestial
navigation and old fashioned dead reckoning get forgotten.

