Might be time to buy a sextant

srm

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I didn't accuse anyone of fetishism or practising magic.
Really?

At times you come across in the same way as the worst type of politician. The ones that keep fervently repeating specious arguments (and possibly believe they are right) even when their supporters realise how ludicrous they are.
 

Daydream believer

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I learned to do the moon, planets and stars as well as the sun from my back garden with the reflection in a dish of two stroke oil. The reflections of stars in the oil could prove a challenge. At least doing 'sun-run-sun-run-sun' from the same place meant there was no worries about log inaccuracies!
I've never ever used it on a boat. However, I can take pleasure in the instrument itself, knowing I know how to use it.
I suppose that was one use for the fuel out of my Stuart turner. Because it never got used for running the engine-- It never started.
So like you I never used it on the boat- The fuel that is :unsure: :unsure:
 

Buck Turgidson

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Just to add a little levity to the situation. Back in the 1990's I was guesting on another Nimrod crew during a "prestigious bombing competition" the target was a submarine. The highly skilled tactical crew including no less than 3 navigators on this occasion released our dummy load in what was though to be the perfect drop position for it to do it's magic and broadside the submerged vessel. We all sat in excited trepidation waiting for the call of a "hit" but none was forthcoming. Much head scratching was observed as to why no Bang! Until eventually one of Her Majesty's finest navigators admitted that the range was set incorrectly on the tactical display and we were 5 miles off target with the release.

I can admit this because it wasn't my normal crew and I wasn't involved in the tactical part of the operation :)

They were known as the 5 mile wide club from that day on.
 

Buck Turgidson

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Just for fun, here is the fitted periscope sextant on a VC10 in use.
View attachment 147886
Note the flight engineers head in the foreground. Typically at this point he would be doing everything he can to put off the poor nav. I would expect he was poking said officers arse with a pencil as this shot was taken :ROFLMAO:

edited to add: It was also traditional to collect some soot from the engine exhausts or brake dust and coat the eyepiece such that the unsuspecting nav would end up with half or full panda after the star shot!
 

Neil

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I suppose that was one use for the fuel out of my Stuart turner. Because it never got used for running the engine-- It never started.
So like you I never used it on the boat- The fuel that is :unsure: :unsure:
Actually, I never did use the 2-stroke oil on a boat either.:eek: I'd bought a couple of defunct Seagulls- stripped and repaired them out of interest and ran them in a wheelie bin. The state of the water was shocking compared to running a 2.5 HP Suzuki in the same wheelie bin,:LOL:
 

lustyd

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Really?

At times you come across in the same way as the worst type of politician. The ones that keep fervently repeating specious arguments (and possibly believe they are right) even when their supporters realise how ludicrous they are.
Not a single post has shown what I said to be wrong. Lots of blustering, opinions and quoting of advert text, amongst changes of context, but nothing to actually address what I said. There are people acting like politicians here, but it's not me. Avoidance of topic is the speciality of politicians.
 

srm

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Going back a bit in time, during the latter half of WWII bomber command night training flights had a UV sensitive camera fitted. Navigation was by bubble sextant with an averaging mechanism allowing a number of rapid sights of the same star to be take. When over the "target" they took a photo which hopefully (at debrief) included a spot of UV light near the centre. The Isle of Arran had one of the UV targets.
 

zoidberg

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During one of my night-astro training flights, I took a sight with a bubble sextant on a star more or less astern. It was 'in or near' the bubble centred in the bubble chamber, so I did the appropriate corrections, and plotted it.

Later, when my night's work was being analysed by my course commander, I remarked that it had seemed unexpectedly 'red'. He had a think, made a phone call, then announced to me that my 'red star' was probably the port navigation light on the Varsity trainer aircraft just behind in the stream, but a couple of Flight Levels higher up.....

"I flew about learning from that......"

:rolleyes:
 

capnsensible

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Just to add a little levity to the situation. Back in the 1990's I was guesting on another Nimrod crew during a "prestigious bombing competition" the target was a submarine. The highly skilled tactical crew including no less than 3 navigators on this occasion released our dummy load in what was though to be the perfect drop position for it to do it's magic and broadside the submerged vessel. We all sat in excited trepidation waiting for the call of a "hit" but none was forthcoming. Much head scratching was observed as to why no Bang! Until eventually one of Her Majesty's finest navigators admitted that the range was set incorrectly on the tactical display and we were 5 miles off target with the release.

I can admit this because it wasn't my normal crew and I wasn't involved in the tactical part of the operation :)

They were known as the 5 mile wide club from that day on.
Submariners would consider that without operating a noise maker and firing white smoke candles to go 'yoohoo, over here' 5 miles is for crab air quite close...... :)
 

capnsensible

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Not a single post has shown what I said to be wrong. Lots of blustering, opinions and quoting of advert text, amongst changes of context, but nothing to actually address what I said. There are people acting like politicians here, but it's not me. Avoidance of topic is the speciality of politicians.
Have you found an alternative navigational use for your Christmas tree decorations?
 

Praxinoscope

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As my sailing is now more or less restricted to pottering about in the coastal waters of Cardigan bay and Pembrokeshire I haven’t used my sextant for about ten years and no longer carry it, but I won’t sell it, I may need it again one day.
I am sure that it would be possible to use one of the ‘display’ sextants and get a sort of position, but the number of errors likely in the construction of one of these, would I think result in a rather inaccurate position.
 

Rum_Pirate

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My 14 year old son has just told me the world will end In 2 days.
After doing a google search it seems there is a chance of a huge solar storm knocking out satellites. I'm guessing gps could be wiped out temporarily.
I do have an interest in finding my way with the old ways and hope to buy one soon regardless .
You would need to download how to use it as well as getting a set of tables.

Thankfully so far his forecast has been incorrect.
 

AntarcticPilot

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Not a single post has shown what I said to be wrong. Lots of blustering, opinions and quoting of advert text, amongst changes of context, but nothing to actually address what I said. There are people acting like politicians here, but it's not me. Avoidance of topic is the speciality of politicians.
I'm sorry, but your claim that sextants had a history going back "thousands of years" is incorrect, as I pointed out. Sextants and the closely related quadrant and octant go back only to the 17th or 18th century and are completely unlike previous means of finding the altitude of a celestial body; they marked a step change in the attainable accuracy of ship-borne observations. The only one that can be said to go back "thousands of years" is the kamal (it's suspected that the Vikings used something similar, but they were in contact with the Middle East through the Russian rivers and the Byzantine Empire), and a) that can only provide a means of determining when you're on the same latitude as a previously observed location and b) is unusable when the elevation of the observed body exceeds around 60 degreees; it is necessary for the horizon and the observed body to be in the same visual field (60 degrees may well be a very generous estimate). The Crossjack and Backstaff could be calibrated with degrees, so you could determine your latitude using them. But the calibration was difficult, being highly non-linear (I think it goes as the tangent of the angle, but I'd have to draw a diagram to make sure). They also both suffered from the same problem that the horizon and the object of interest had to be in the same visual field, which places severe limits on the range of angles that can be measured.

PS, it's the cotangent of the angle, not the tangent.
 
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jamie N

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Yup, of course, but adapting the electronic end, to the optical functions wouldn't be 'too' difficult.
Modding the 'swinging' arm with a weight to always be pointing vertically down, would negate the need for being able to sight the horizon: simply sight the upper arm on the sun, through the tinted glass, - 90° and job done, providing the swinging arm can be guaranteed to be vertical, wouldn't it?
Not trying to be contentious, but it seems a solution to me, not as a navigator, but as an electronics engineer.
 

Praxinoscope

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#159, seems to be a case of trying to re-invent the wheel, by the time the required optical gubbins have been added you may as well buy a sextant.
 
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