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Old Today, 07:11   #61
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Re: Considering ditching electronics and navigating the "old" way

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Originally Posted by barnakiel View Post
You got me interested :



How do we skip the sextant thing?


I understand the chart can be skipped too when we know how to make a plotting sheet.



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Timing sunrise and sunset. Day length giving the latitude position line (+- Nm sailed W or E) and excact time giving the line to plot longitude. Of course it works with other celestial bodies as well but needs a bit more calculations. Equinox is best spend fishing if latitude plot is essential..
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Old Today, 07:25   #62
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Re: Considering ditching electronics and navigating the "old" way

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They did run aground with what we would now consider shocking frequency though. Turns out celestial navigation does nothing to help you avoid collisions with other ships (unless I missed that part of nautical science class at the Academy?) and does a passable but not great job of telling you where you are.
But it does as with the presumed uncertainty of celestial navigation and dead reckoning keeps you more alert of the surroundings, anyway what comes to other vessels. Wonder what makes a Navy ship to do "crazy Ivan" over TSZ without lookout? Bad charts and no fix of course are hazard waiting to happen..
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Old Today, 08:07   #63
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Re: Considering ditching electronics and navigating the "old" way

Another way to skip the sextant is to take the time when the upper limb of the sun just disappears at sunset. Reduce that as a zero altitude sight. I suppose it would also work at sunrise except Iím never awake enough to try it.
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Old Today, 08:42   #64
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Re: Considering ditching electronics and navigating the "old" way

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Timing sunrise and sunset. Day length giving the latitude position line (+- Nm sailed W or E) and excact time giving the line to plot longitude. Of course it works with other celestial bodies as well but needs a bit more calculations. Equinox is best spend fishing if latitude plot is essential..

OK.


I have not tried the latitude from day's duration, but I will try it on our next crossing.


But the longitude for sunrise sunset I have tried and I must report HUGE errors encountered. I can't tell why I got such big differences, all I know they were there - within 2 degrees or so.


I must try harder.




Which of the two methods have you tried, and how close to your position did you get?



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Old Today, 10:04   #65
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Re: Considering ditching electronics and navigating the "old" way

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Originally Posted by barnakiel View Post
OK.


I have not tried the latitude from day's duration, but I will try it on our next crossing.


But the longitude for sunrise sunset I have tried and I must report HUGE errors encountered. I can't tell why I got such big differences, all I know they were there - within 2 degrees or so.


I must try harder.




Which of the two methods have you tried, and how close to your position did you get?



barnakiel
Neither for navigation but tried a couple of times for curiosity.
The contingency lies in the weather as the sun is not allways the where it seems to be and closer to equinox the latitude accuracy suffers a lot. Most times you should be in five to ten Nm circle, enough for open seas and to get destination visible..
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Old Today, 16:28   #66
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Re: Considering ditching electronics and navigating the "old" way

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But it does as with the presumed uncertainty of celestial navigation and dead reckoning keeps you more alert of the surroundings, anyway what comes to other vessels. Wonder what makes a Navy ship to do "crazy Ivan" over TSZ without lookout? Bad charts and no fix of course are hazard waiting to happen..
So we should use an inferior form of navigation to make us more alert to other vessels that could be a collision hazard?

Seems that spending more time focusing on radar skills, rules of the road, and proper watch keeping would be the best way to minimize the risk of collisions, but hey what do I know. I guess in some crazy alternate universe up is down and purposely handicapping your situational awareness and requiring you to be heads down doing nav calculations for significant time periods makes collisions less likely?

I had the unique experience of having to use celestial nav exclusively on the Eagle (295' Barque) and using modern nav tools as OOD on several Coast Guard cutters. Curious what your experience as an OOD on a large ship relying on celestial navigation in crowded seas has been to lead you to the opposite conclusion as me?
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