Poll-Blue water. Is a Sextant Necessary?

[Andrew Troup]

Originally Posted by Celestialsailor

I see most of what I need is here...
The Astronomical Almanac Online -- Welcome

Have you tried actually using this online facility? Unless both my browsers are broken, it only offers a very small amount of info, which appears not to include anything a recreational navigator would need.

It seems that most of the headings on each page are advising you what info is in the printed edition, rather than what is available online. IOW, they are not (generally speaking) links which go anywhere.

As I understand their cryptic comment from their home page "The online version extends the printed version by providing data best presented in machine-readable form":

What they mean is that the purpose of the website is to act firstly as an index to the section in the hardcopy printed publication,
and secondly to provide supplementary, rather arcane info, which is ill suited to the printed version, and presumably therefore not included in the printed version.

[Celestialsailor]

Originally Posted by Andrew Troup

Have you tried actually using this online facility? Unless both my browsers are broken, it only offers a very small amount of info, which appears not to include anything a recreational navigator would need.

It seems that most of the headings on each page are advising you what info is in the printed edition, rather than what is available online. IOW, they are not (generally speaking) links which go anywhere.

As I understand their cryptic comment from their home page "The online version extends the printed version by providing data best presented in machine-readable form":

What they mean is that the purpose of the website is to act firstly as an index to the section in the hardcopy printed publication,
and secondly to provide supplementary, rather arcane info, which is ill suited to the printed version, and presumably therefore not included in the printed version.

Perhaps you could suggest another one. That would be useful.

[Celestialsailor]

My feeling is that if Celestial navigation classes were more accessible to the common sailor, more folks would have the skill of navigating via the celestial bodies. Very few places offer it. One of our own, SkiprJohn, taught a class while I was on the Big Island. Although I never took it. Here is a site with a PDF of how to. Please...if you don't like it...keep it to yourself.

http://mysite.verizon.net/milkyway99...tionTeacup.pdf

[nigel1]

Originally Posted by Celestialsailor

Perhaps you could suggest another one. That would be useful.

How about this one

Celestial Algorithms

Install, run and print the pages you need

[Ex-Calif]

For those that repeatedly point out the errors that those new to gps make, can you not allow there are a similar numbr of errors (at least) possible when learning celestial?

So make the error of use point moot. Either one you use, you must know how to use.

No one uses a sextant to make a harbor entrance - you use visual.

No one is suggesting to use gps alone to make harbor entrance. Use visual. However, when socked in and in the right harbor gps is more usable than a sextant for "blind" navigation.

For Pete's sake airplanes use gps IFR approaches to arrive at airports (at a lot faster speed than 5 knots) every day.

Errors in charting and datum are left - using the wrong datum goes to operator mistake.

Land features that are not accurately located on the chart are in the wrong place whether paper or electronic.

[Jim Cate]

Originally Posted by Andrew Troup

If you have to sail routinely in parts of the world where the charts have land the right shape but in the wrong place (which is the usual problem), there's a third option apart from GPS and celestial which some of the above posters are overlooking.

Position fixing with direct reference to land features and nav markers, immunises you from chart datum problems and inaccuracies.

IOW, 'land relative' navigation methods are not affected, 'global absolute' navigation is. And of course a sextant is helpful for pinpointing 'land relative' positions.

This will not interest those who sail only in well-surveyed waters, but for those venturing far from the beaten track, it's another reason to keep those skills alive (or acquire them)

Last year I visited the bridge of an Australian warship in Hobart. The duty officer was showing everyone the multiple GPS based systems they had, but I was looking at the paper chart on the chart table. It covered the Derwent Estuary... a good, well surveyed modern chart. It was covered with pencil lines of position taken from land objects. On direct questioning, the officer admitted that in close waters like these they relied upon LOPs and fixes from such observations rather than the electronics. Their pelorus got a good workout on that stretch!

Must be a reason...

Cheers,

Jim

[David_Old_Jersey]

If both are used well then IMO GPS is the clear winner .

As said, can't cure stupidity with any gadget - overall around these parts the GPS has made life safer (as well as easier!)....... it's just that the nature of the stupidities has changed (folks used to head ashore in places they had misidentified, especially at night) whereas now they come ashore from being closer than they would have been, so when things go wrong they have less searoom to play with (GPS makes folks less prudent / cautious navigators).......overall a win for GPS on numbers of incidents.

Of course the above very little to do with Sextants!


Personally I think that GPS has taken away from many the "magic" of a landfall being vaguely somewhere near intended . both plusses and minuses to that........

[Andrew Troup]

Imagine a thread entitled "Are sails necessary ?"

Clearly the answer is "No"

Sailing is a literally pre-historic way of going slowly and inaccurately in various semi-random directions at great expense and with the expenditure of unnecessary physical and mental effort.

Now why would anyone want to do that?

[micah719]

Do you prefer to be keel-hauled over the port side, or the starboard side?

p.s. you can scrub me bottom while you're down there; I'll staple a scotchbrite pad to your chest.

[44'cruisingcat]

Originally Posted by Jim Cate

Last year I visited the bridge of an Australian warship in Hobart. The duty officer was showing everyone the multiple GPS based systems they had, but I was looking at the paper chart on the chart table. It covered the Derwent Estuary... a good, well surveyed modern chart. It was covered with pencil lines of position taken from land objects. On direct questioning, the officer admitted that in close waters like these they relied upon LOPs and fixes from such observations rather than the electronics. Their pelorus got a good workout on that stretch!

Must be a reason...

Cheers,

Jim

The reason would be - training. In a war, it's possible the GPS satelites could be targeted.

[micah719]

If car thieves can jam GPS, so can others. Imagine the brouhaha if one of HM's Aussie Ships went aground because someone ashore happened to be requisitioning a nice Beemer......not an excuse I'd like to try at the CM.

[SkiprJohn]

I believe keel hauled was stern to bow and always fatal.

Celestial let it be know that I too still practice "the Dark Arts" from time to time.

kind regards,

[micah719]

I believe keel hauled was stern to bow and always fatal.

Oouch! And that was only with long keels, imagine meeting the modern fin, or bulb...that's if you get past the prop, I guess.

[songbird]

Someone mentioned Marvin Creamer and his fantastic accomplishment of sailing around the world without navigation equipment. No one has yet mentioned that he did carry a sextant, clock, compass and radio sealed in a locker below decks in the EVENT OF AN EMERGENCY (my emphasis). Knowing how to use a sextant goes with the many other skills that a competent sailor should know so that one can be self reliant and not trust on others to save ones bacon.

[sailorboy1]

Amazing the lengths some here will go to try to make the sextant sound needed.

But 84% of poll takers still say ............. NO!