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Old 13-07-2011, 10:26   #46
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Re: Tecnology vs Sextant

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Originally Posted by s/v Beth View Post
I think this sextant thing is much too hard. Why do I want to do math in the middle of the pacific? identifying trash in knowing the current seem a lot easier. I just need to learn how to identify chinese trashed as opposed to japanese trash. yeah I think trash navigation has great promise!
That's easy. The Japanese script is more regularized (falling within a square) and the Korean script is even more so. Otherwise, it's probably some other dialect non-specific Chinese. Thai is easy to recognize, as is Cambodian (which admittedly looks something akin to Sinhalese). Vietnam uses a modified Roman script and Bahasa (Indonesia or Malaysian) also uses a Roman script.

... on second thought, it might be easier just to learn the math.
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Old 13-07-2011, 10:30   #47
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Re: Tecnology vs Sextant

I also understand that the way from the U.S. West coast to Hawaii is just following the jet contrails.
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Old 13-07-2011, 10:33   #48
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Re: Tecnology versus sextant

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Originally Posted by Vasco View Post
If you can do this on a small boat bobbing in the ocean you're a better man than most navigators I've met.
Including Captain Cook.
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Old 13-07-2011, 10:35   #49
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Re: Tecnology vs Sextant

its not the math thats hard. Its the interpolation mistakes you make when transcribing or doing small calculations on a moving boat, or operating the sextant. Starting a stopwatch and recording the time from a chronograph, taking a sight, then recalculating the exact time from your recorded time + stop watch...to walking through all the adjustments from the almanac or tables while cross eyed from lack of sleep and movement (oops wrong figure!)...or maybe averaging a number of sights for a fix. And so on and so forth....
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Old 13-07-2011, 11:07   #50
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Re: Tecnology vs Sextant

Hmmm. Why hasn't someone invented an electronic sextant? Point it at the celestial object, line up the horizon, and press the button. Voila! Instant line of position. Could probably be done for $1500 per unit, batteries not included.
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Old 13-07-2011, 11:17   #51
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Re: Tecnology vs Sextant

You can do significant celestial navigation with very simple sights and calculations. There's noon sights, object rising and setting times, height of the north star, etc, that are pretty handy for backup landfall type navigation.

For example, loss of GPS on a North Pacific return to North America .... one of the bigger chunks of open water .... keep Polaris about 40 degrees above the horizon to stay on the 40th parallel .... with a good watch and any rudimentary almanac the rise time of the sun or moon will give one a rough idea about when to start worrying about a landfall. Then near California a passing freighter, fisherman, radar or simply smoggy skies will direct one to a port where beer and such will solve the problem completely.
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Old 13-07-2011, 11:18   #52
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Re: Tecnology vs Sextant

Last summer I actually lost GPS in a storm due to a lose connection in the antenna cabling. I like to use a sextant and practice with one any chance I get, and so I would love to say that I just got my trusty sextant, reduction tables and almanac out and got my position by taking a noon sight. Well if my life were a novel, that would be exactly what I did, but in reality, I didn't see the sun for another 48 hours, and had the GPS up and running in 24 after things calmed down enough for me to check out the cabling. I already knew pretty much where I was at the time the GPS went down so I really didn't have any worries about that. I could DR based on wind and current data easily enough, and a visual sighting of Cape Scott at the North end of Vancouver Island pretty much exactly fixed my position. DR based on wind, waves and current, confirmed by a landfall fix is about as basic as one can get.
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Old 13-07-2011, 11:24   #53
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Re: Tecnology vs Sextant

You can do significant offshore navigation WITHOUT a sextant and a simple pocket watch. You can also manage WITHOUT either. I suggest that you learn to do this first. It will not only add to your arsenal of tools but make you a better more confident celestial navigator (you'll understand a lot more) when you pick up those more exact skills. You may even find you don't really need a GPS or sextant for most of the more general places you are headed.
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Old 13-07-2011, 11:30   #54
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Why should you do math in the middle of the ocean? To keep your mind sharp and be a more proficient seaman...

Here is a grabber...and, ok, maybe a corny comparison...the movie castaway, (which I thought was a comedy) if mr man there had skills, ie boat building, navigation, wilderness survival, etc...he might have been in better shape and home sooner...
Scouts motto...be prepared...
Puddle pirates motto...Semper Paratus..
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Old 13-07-2011, 11:35   #55
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Re: Tecnology vs Sextant

zopi - sorry, all those things you cite are refutable.

Boat building skills? with what?
navigation? to where?
wilderness survival? he learned. moreoever survival is survival - meaning to exist as long as one can; NOT living skills meaning to exist for generation.

True story:

In an interview they asked the director "what was in the fedex box he delivered?"

The director said "A water proof satellite phone with a built in GPS"
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Old 13-07-2011, 11:36   #56
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Re: Tecnology vs Sextant

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Hmmm. Why hasn't someone invented an electronic sextant?
Someone already has:

http://www.patentstorm.us/patents/41...scription.html

see also:

Navigation 0204: Re: Digital Sextant
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