Might be time to buy a sextant

[lustyd]

I notice you put your location down as " . " Is that because you are still trying to work it out using a home-made chart and and Indian made "sextant" bought on eBay? ?

That's because I don't want crazy people from the Internet chasing me down and trying to convert me to sextant navigation by force. I'm happy with GPS and the occasional play with a sextant, I'm not ready to commit to the lifestyle. Heck, I can't even grow a decent beard, let alone smoke a curly pipe

 

[Kukri]

I read his book when I was at school:

“ In 1930, he decided to emigrate to the United States. Fred Rebell was not his original name but one he assumed when he forged seaman's papers to escape from Germany to Australia about 1907. Lacking a passport, he was unable to obtain a visa and decided to make his own way. He purchased an 18' sailing regatta yacht* and sailed single-handed from Australia to Los Angeles starting around 1931. Lacking funds for navigation instruments, he made his own sextant from scrap parts including using a hacksaw blade as a degree scale. He did so with a self-created passport. He landed on various Pacific islands en route — spending as long as five months repairing his boat. He arrived in San Pedro, California, in 1933 and is recorded as the first ever solo crossing of the Pacific Ocean from west to east.”

Fred Rebell - Wikipedia

* Actually a clapped out 18ft skiff!

 

[guernseyman]

What the OP's son, and another couple of posters, may have been referring to is the possibility of the earth's magnetic field flipping, i.e. reversing north and south. This happens on average about once every 200,000 years. The process takes about 1,000 years and during that period the earth may lose protection from radiation from the sun, and elsewhere.
Changes in the magnetic field do not necessarily mean a flip is about to take place and, in general, it is thought unlikely that a flip would be predictable until well after it had begun. Thus, as far as I know, the current background chatter about the possibility is unfounded.
Although dangerous, past flips do not seem to have completely extinguished life on this planet.

 

[coopec]

An interesting list for those planning to create their own charts, use for their work, or those fetishising these simple objects. As with kitchen knives though, those first learning the skills don't need the ultimate tool.

"

Does this description mean anything to you?


Size :- 12.70CM
Material :- Solid Brass
Color :- Brass Finish

Hand-Made Item
Nautical Decor Item

This item is made for decoration purposes and whilst it may have some functionality it has not been designed as a working instrument.

SOLID BRASS NAUTICAL ASTROLABE MARINE SEXTANT / NEW | eBay

 

[AntarcticPilot]

The concept us much older than 18th century. As I said, try the national maritime museum in Greenwich.

I have, and have taken an interest in the development of marine navigation for most of my life, as well as it being of professional relevance. The only instrument using a similar principle to the sextant is the quadrant, which (I forget without looking it up) predates it by a century at most. The earlier instruments used different principles and were considerably less accurate, as well as being useless in latitudes below about 30°. The driving force behind the development of the sextant was the determination of longitude by lunar distance; the quadrant was adequate for latitude from sun or stars.

Yes, in temperate or polar latitudes the Kamal, crossjack or backstaff can be used with precision adequate to make a landfall. But the development of the quadrant and sextant represented a quantum leap in the accuracy attainable; an accuracy that had previously only been available to land based observatories.

 

[lustyd]

Does this description mean anything to you?

Interesting. So when you ordered one and tried it, specifically how did it fail to work aside from lower accuracy? I'm not saying they should be used, I'm saying that they would almost certainly work.

 

[coopec]

Interesting. So when you ordered one and tried it, specifically how did it fail to work aside from lower accuracy? I'm not saying they should be used, I'm saying that they would almost certainly work.

I ordered one "for decoration purposes" as well as a "vintage" compass.
THEY COULD NOT BE USED FOR NAVIGATION

Do you understand what they are saying here?
"This item is made for decoration purposes and whilst it may have some functionality it has not been designed as a working instrument."

Do you understand!

 

[capnsensible]

The concept us much older than 18th century. As I said, try the national maritime museum in Greenwich.

I did when I was learning, for sure. Did you buy the premium version to learn with every time you tried something new? Was your first compass fully calibrated or a POS out of a Kellogs box?
Have you tried one of these terrible quality protractors of death? Usually a master can make do with inferior tools so I'd be interested to see how good of a fix could be managed by someone with good experience.

So you maintain your yacht with cheap and nasty rubbish tools. Oooer

 

[lustyd]

So you maintain your yacht with cheap and nasty rubbish tools. Oooer

I didn't say that though, did I?

 

[lustyd]

I ordered one "for decoration purposes" as well as a "vintage" compass.
Do you understand!

So you haven't tried it then? Or you have and there were no issues you're able to explain. Did you understand my question?

 

[coopec]

So you maintain your yacht with cheap and nasty rubbish tools. Oooer

No point in arguing with iustyd
(I sometimes wonder who does their shoelaces up for them each morning)

 

[lustyd]

No point in arguing with iustyd

(I sometimes wonder who does their shoelaces up for them each morning)

We're not arguing. You're ranting and I asked a question. Twice.

 

[zoidberg]

It's probably OK, now, to mention the sort of repeatable accuracy that was achieved by the RAF's Vulcan bomber crews over half-a-century ago, using 'astro'. I almost mentioned 'average', but those crews were certainly not average.

They were 'selected', worked as a highly-trained team of five, and used a pair of sextants calibrated within a 'smidgen' of precise, mounted on a 4-jet 'flying triangle' batting along at 8 miles/min and operating some 7 or 8 miles up - and the accuracies they could and did achieve astounded their American counterparts using vastly-expensive 'star trackers'.

Each one of those crews was required to demonstrate, after a 1500nm flog around the North Atlantic ( or similar ), bringing the aircraft down along a pre-planned lane in the sky just 1 nm wide, to better than 20 seconds of pre-planned time.... each and every month.

The better crews could consistently 'fly down a lane' just half a mile wide and within 5 seconds of pre-planned time. These were the guys who competed in the prestigious but secretive 'NATO Bombing Competitions'. The point was to demonstrate the capacity to drop a 'notional' bomb near as dammit down the chimney.

Our dear friend 'lustyd' might mock at this intensity of sustained training effort, at the honing of team-work skills to Olympian levels, at the constant re-calibration of a host of integral instruments to perfection, building performance over years of striving, towards a capability that all involved prayed would never be used.....

It all seems rather futile now, and one is left to follow the passages being made at present in the Southern Ocean by a handful of sailing stalwarts, with their sextants, wind-up chronometers, and occasional glimpse of the sky.

 

[lustyd]

Our dear friend 'lustyd' might mock at this intensity

Why would I have an issue with it in pre-satellite days in a setting where accuracy was important? I feel like you've misinterpreted everything I said.

 

[srm]

I feel like you've misinterpreted everything I said.

Well he is obviously a lot politer than you. No unfounded accusations of fetishism, practicing magic, or even buying gold plated cables for some nefarious reason.

 

[lustyd]

I didn't accuse anyone of fetishism or practising magic. I did suggest you were the target demographic for unnecessarily gold plated digital cables, and I stand by that as you do seem to believe that any and all improvement is necessary.

 

[zoidberg]

Why would I have an issue with it in pre-satellite days in a setting where accuracy was important? I feel like you've misinterpreted everything I said.

That's unlikely, 'lustyd' m'dear. I haven'tactually listened to everything you've said. And, yes, this old codger does have a fetish - but it isn't sextants.

I am, however, intrigued by the graphic you have chosen to use.....

 

[lustyd]

I am, however, intrigued by the graphic you have chosen to use.....

Strictly speaking I wouldn't call it a graphic, it's a boat name.

 

[Gadget257]

It's probably OK, now, to mention the sort of repeatable accuracy that was achieved by the RAF's Vulcan bomber crews over half-a-century ago, using 'astro'. I almost mentioned 'average', but those crews were certainly not average.

They were 'selected', worked as a highly-trained team of five, and used a pair of sextants calibrated within a 'smidgen' of precise, mounted on a 4-jet 'flying triangle' batting along at 8 miles/min and operating some 7 or 8 miles up - and the accuracies they could and did achieve astounded their American counterparts using vastly-expensive 'star trackers'.

Give that that the V bombers were designed to carry nuclear weapons with a yield of many hundreds of kilotons of explosive power pinpoint accuracy launching down chimneys was not too important

 

[srm]

Give that that the V bombers were designed to carry nuclear weapons with a yield of many hundreds of kilotons of explosive power pinpoint accuracy launching down chimneys was not too important

In which case you missed the reason GPS was originally developed: to hit a 20 metre diameter hatch on a missile silo as anywhere else was a failure. The V bombers could and did carry other payloads, as was demonstrated during the early stages of the Falklands war.