SailNet Community banner

1 - 20 of 58 Posts

·
Registered
Joined
·
3,070 Posts
Discussion Starter #1
While sailing far offshore I came across a flotilla of Naval ships. They were lost due to a EMP (electro magnetic pluse) that wipe out their electronics including those chart plotters... Even their gyro and fluxgate compasses were down.
Using flashing light they were able to communicate their problems to me. Several Naval ships and not one sextant between them. Thus they were lost.

So using my trusty C Plath Sextant, I plotted a position for them and then led them back to port with my old fashion magnetic compass and giving them a position fix every hour as we progress toward their port of call.

After the ships were all moored, the Admiral sent all of the ships navigators over to my boat and for the next few weeks I taught them the old fashion way of navigating. The Navy acquired sextants and pubs for all of their ships and Electronic navigation was looked on with a lack of trusting suspiction.
 

·
ancient mariner
Joined
·
439 Posts
were they U.S. Navy ships? i find it hard to believe even the gyro & mag compasses were completely down! no sun or stars to get some idea of where they were heading?
 

·
Registered
Joined
·
3,070 Posts
Discussion Starter #3
The Dumb Politicans had thought they would have big savings by not buying or maintaining the magnetic compasses... And Gyro compasses are subject to EMPs

Note: Sea tales are another form of tales that may start with "once upon a time" or "this is no sh*t".
Note2: With the rush to all electronic & computerized bridges, some people would do away with the magnetic compasses. So my sea tale is probable.:D
 

·
Registered
Joined
·
3,070 Posts
Discussion Starter #5
What would an EMP to to a handheld GPS which was not activated and stowed?:confused:
Do you have it stowed in a Faraday Cage??
If not it will make a good paper weight. :laugher
 

·
SouthernComfort
Joined
·
59 Posts
I saw a show on the history channel about Harrison's Timekeeper and it showed navigators on modern US navy ships using sextants as a back up. They still carry timekeepers too.
 

·
Registered
Joined
·
1,940 Posts
Why were the gyrocompasses affected? To my understanding, they don't rely on electronics.

Also, when/where was this? What was the source of the EMP? Are we doing offshore nuclear testing now?
 

·
Registered
Joined
·
511 Posts
There was a movie like this a few years back. One of the big carriers ran into an electromagnetic storm off Hawaii that caused it to travel back in time to December 7, 1941. Ridiculous premise, fun movie watching the F-15s fly past the Zeros.
 

·
Unpaid Intern
Joined
·
992 Posts
There was a movie like this a few years back. One of the big carriers ran into an electromagnetic storm off Hawaii that caused it to travel back in time to December 7, 1941. Ridiculous premise, fun movie watching the F-15s fly past the Zeros.
OK, I'll embarrass myself here and mention that movie was actually 29 years ago, yes it was really dumb, and they were F-14s. Don't ask me how I know, because if I have to explain myself I might have to jump off a tall bridge.
 

·
Banned
Joined
·
711 Posts
You coulda just said you picked it up on dvd recently. "The Final Countdown".
 

·
Registered
Joined
·
3,070 Posts
Discussion Starter #13
Gyros are affect by EMP due to that their amplifiers & distribution boards are electronic.
 

·
Closet Powerboater
Joined
·
3,925 Posts
Having never learned the art of celestial navigation I ask these questions in earnest:

Is there any electronic equipment required (or used regularly) for celestial navigation?

I really like the idea of a non electric form of navigation for many reasons (EMP, lightning etc) but I wonder if there is an electronic component we are missing. Don't you need exact time in order to do CN? So do I need to add an expensive antique wind up (or perhaps Seko motion watch) chronograph to my list of gear? How about the calculator? I hear CD is math intensive. Can it be done by mere mortals without a calculator or do I need to learn slide rule as well?

Not taking the piss, I actually have been thinking about these problems for a while. I wondered how many folks feel warm and fuzzy for having a sextant in case of lighting but are expecting to use a calculator and quartz watch to assist...

MedSailor
 

·
An Aussie Sailor
Joined
·
122 Posts
I also know nothing of celestial navigation but isn't there books of tables to take out the need for math calculation?

Mychael
 

·
Splashed
Joined
·
572 Posts
CN is simple

You will need a sextant, a watch, a current-year Nautical Almanac (or one that is 4 yrs old) and the Tables of your choice, like the HO 249 or HO 229 - marine or air sight reduction tables.
Then it is just a matter of simple addition. An accurate timepiece is great, but as long as you know how much your timepiece looses or gains, you can live without the digital watch.
 

·
Registered
Joined
·
3,070 Posts
Discussion Starter #18
And without the accurate time piece you can go back to Westing and Easting by sailing down or up to the lattitude of the port you are headed for and sail East or West.
You can find your lattitude with noon sights and the North star. And aim a little above that port so when you do make landfall you know which direction to turn in order to enter that port.
And you used Moon distance to find the Longitude and the time to correct your inaccurate pocket watch.
 

·
Registered
Joined
·
3 Posts
One might reasonably ask, "with GPS why does anyone need to bother with such an arcane and complicated process as celestial navigation using sextants?". Good question! Some good answers are, electronics fail at sea. GPS positions are often intentionally made inaccurate by the military for various reasons of national security. With the retirement of the LORAN system, there is no other backup for GPS satellite constellation. The GPS satellites themselves are aging and aren’t being replaced as quickly as they should. The replacement GPS satellites are over-budget and years behind schedule. Lastly; with satellites we are placing our major navigation and communications eggs in one basket, with one single point of failure. I don't really believe that man-made EMPs are that likely, but; it would only take one CME from our sun or one GRB anywhere in our galaxy to knock out every satellite, all at the same time. These events are rare; but they do happen, especially likely are CMEs and solar flares. I also think it’s fun to learn new skills and learn how our world was explored and mapped by people using nothing more than their celestial knowledge. :)
 
1 - 20 of 58 Posts
Top