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Old 27-05-2009, 06:23   #31
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Amen, Brother Blu!
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Old 27-05-2009, 16:09   #32
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Sextant use

On my second trip to the VI from the Chesapeake in the earlt 70's we had a young merchant mariner (Second officer) on as navigator who taught me how to take sights using mostly stars at dusk and dawn when there was enough horizion.

I asked if they used Celestial nav on the large cargo ships he worked on. He told me that they rarly did and used mostly DR. He further explained that if you point something with a 800ft waterline doing 20 knots at something it generally arrived at the point at the predicted time. Nice work when you can get it!
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Old 01-06-2009, 20:22   #33
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Question Lost at Sea

Yeah, another vote for the wisdom of RetiredSailor and Blu. Love my GPS, but traditional nav skills are what I rely on. No boat is safe without them.

Most memorable advice I ever received on electronic navigation?
"Just look out the f***ing window."
Apt, given comments here on jet trails, birds, liners, etc. A Polynesian method of finding land is to watch where (nesting) birds fly to at dusk. Don't try this with your average albatross.

And for those interested in learning astral navigation (as I am), or who simply want to identify the stars and planets - here is cool / free software showing where to look for all the major stars, planets, etc. Should help you learn the relative positions of the major stars. Tell the program your location, and it will show you where items of interest should be found.

http://www.stellarium.org/

Versions exist for Windows, Macs & Linux (size ~40 Meg by memory)

Now I just have to work out the rest of this astral stuff ...
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Old 25-06-2009, 09:32   #34
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Originally Posted by roger.waite View Post
"Just look out the f***ing window."
Hahaha! I love it ... I was investigating a marine casualty one night and the Captain told me he found his way home by reversing his GPS trackline - he hit boat on a mooring ball!

If ancient mariners could have used electronic navigation they would have. The problem with relying on electronics is you rely on electronics and lose your tactile senses. I've witnessed Captains stareing at chartplotter screens and their waypoint tracklines ... as long as the triangle was on the line they were happy! Ugh! When the whole GPS system doesn't work and I'm in fog or in the middle of an ocean, I better be able to tell my wife I know where we are!

Remember, "Just look out of the f***ing window."
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Old 25-06-2009, 10:18   #35
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I count 18 posts that assume electronic navigation will disappear in a puff of smoke six times a week. Lightning will strike and not even your self-tailing winch will work. Then our hero will whip out his trusty sextant and save the day. Our hero-ier bare-chested heros (with a glint of steel in their eyes) will whip out a ball of string and a wooden spoon, and shoot the tidal race into a protected harbour at night in a monsoon.

Reality Check: When a cheap, battery operated GPS wrapped up in aluminum foil with a handfull of alkaline batteries will emerge unscathed and perfectly functional from absolutely any lighting strike, or almost any onboard fire, is there any reason, other than boasting or historical re-enactment, to maintain my skills at celestial navigation? What?, you think somebody is going to turn technology off?

Every other traditional boating skill truly has a place, but celestial Navigation, a relatively recent invention, has no more value today than other Renaisance inventions, like blood-letting. Hmmm. that is a thought provoking parallel....

I knew how to use a sextant. I have two, one is in the closet and the other is, er, well, somewhere. My books are out of date, it would take me three days to get the math right on a worksheet, and several weeks to get the stars right, with a starchart. And even then I would be lucky to get within ten miles of my real position. But the cheapest, oldest, smallest gps I own can take a fresh battery and find its location from a cold start in a matter of minutes, and then tell me PRECISELY which way to go, and track my progress minute to minute, not noon to noon. And it will be a lot more accurate than many of the charts I own, yet it can hide in a soup can with enough spare batteries to last weeks.
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Old 25-06-2009, 12:40   #36
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I have two, one is in the closet and the other is, er, well, somewhere.
If you feel like donating, er ... selling one let me know.
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Old 25-06-2009, 20:59   #37
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As for me I will stick with the sextant and compass, they are not the only navigation aids I have, just generally the most reliable. The most useful navigational instrument is the hat rack between your ears. It is folly to depend on any one method for navigation.
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Old 25-06-2009, 22:12   #38
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captan58sailin, he say:
Quote:
It is folly to depend on any one method for navigation.
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Old 25-06-2009, 22:21   #39
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Capn58, you make a lot of sense. IMO
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Old 26-06-2009, 14:37   #40
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Navigation = the art of being comfortable with not knowing exactly where you are
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Old 26-06-2009, 16:01   #41
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I count 18 posts that assume electronic navigation will disappear in a puff of smoke six times a week. Lightning will strike and not even your self-tailing winch will work. Then our hero will whip out his trusty sextant ...
It is more complicated than that. It is dangerous to rely on chartplotters in some areas that our members sail. Without lightning or the curious humours of the gods, I have lost both my GPSs in fog. To rely only on GPS a skipper - knowingly or unknowingly - makes assumptions:

[1] Electronic charts are always accurate (e.g. third world? and note boats wrecked on that Australian reef the e-chart did not show);
[2] There are no situations - masking, interference, orbital, technical or military - in which GPS is imprecise;
[3] We never want to see a picture bigger than our screen;
[4] We can make a GPS do everything a skilled navigator can do;
[5] Inconvenient coincidences don't happen at sea.

I think someone else has said it in this thread, but safe navigation is about estimating your position using two independent means. I believe that my vessel has been much safer in tight corners because I don't rely on GPS. But I sure am glad to have it ...
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Old 26-06-2009, 17:51   #42
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A fellow crazy kiwi (now gone unfortunately) came up with a TRIED AND TRUE method used by the early Polynesians. His name was Dr. David Lewis (extraordinary guy!! sailed to antartica in a 30 foot steel sloop!). He came up with the idea of "sensing directions" using currents, stars, clouds, sea birds and seaweed!! The old buggar was right on the button (most!) of the time! He wrote some very interesting books about his findings and are well worth reading. It seems we all have an inbuilt "compass" if you like. Much like birds have when mirating and its a matter of training ourselves to use it. My GPS(s!) work fine!!! :-)
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Old 26-06-2009, 19:33   #43
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Chart plotters, Roger? did I say chart plotter? You have strayed from the fold! My comments are limited to two methods of determining a geographic position on the face of the earth: A simple GPS vs a complicated sextant. Anyone who insists their celestial skills are more reliable is a strictly fair weather sailor. If he has a GPS aboard and is not using it, he is unsafe, or imprudent at the very least. If he thinks he is more accurate than a GPS, he has an attitude problem. If he thinks that he will get a fix more often than a GPS he has been reading entirely too many survivalist magazines. At last count, weather has been bad enough somewhere to prevent a star shot or a noon sight FAR more often than GPS service has been interrupted (with advance warning in clearly identified geographical areas) So: your first three points are irrelevant*, the fourth is disingenuous, and the fifth is a homily.

Now, if you are counting on post-apocalyptic survival, in a Waterworld kind of scenario, all your arguments are just fine, but your presumptions are revealing!

*Chart issues apply equally to either method of location.
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Old 28-07-2009, 18:52   #44
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How ?

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I did it.....

So, tell me this: Just how in the world could you lose all electronics aboard if you took the few recommended precautions?
One nuclear misunderstanding will do it for you in 1 / 1,000th of a second: with very little chance of repair or swapping to backup electronics. One good security scare might result in scrambled navigation signals for some time. If you were checking GPS with old standard methods there is a chance you'd notice.

Don't know about the recommended precautions safeguarding against the above ?
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Old 28-07-2009, 20:06   #45
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Is it worth revisiting the original purpose of the thread, which invites those interested in traditional navigation to learn from each other?

I take GPS problems as given having seen multiple GPS units fail, anomalies between paper chart and GPS fix, etc. But I also understand 'first world' sailors might take a different approach.
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