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Thread: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

  1. #1
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    Default Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Long, long ago, I bought a secondhand C. Plath Navistar Classic, from JD Potter in the Minories, the street that runs down to Tower Hill in, or to be exact just outside, the City of London.

    And for the next quarter of a century we got along fine. It had a 6x30 and an artificial horizon, and it was easy and pleasant to use.

    Then I forgot to take the two AA batteries out of the handle.. As the Pardeys say, green gunge.

    I sent it off to B. Cooke, in Hull, JD Potter being long gone by this time, and asked them to fix the electrickery and re-certify it. After a while, they phoned to say that they said that they had no spares and anyway it didnít fit in their collimator, but would I like to leave it with them and a spare handle might turn up..

    That was four years ago. Two years ago I bought WJ Morrisís excellent book on the repair of sextants. His views on the electrical ineptitude of C.Plath are much the same as mine..

    https://sextantbook.com/2012/12/05/c.../#comment-8053

    Last week I spotted a perfectly nice twin of my sextant on EBay for sale in Poland, without a telescope, and I bought it, thinking that I would get at least one if not indeed two sextants in working order.

    Its in lovely condition, including the battery handle and micrometer light.

    Can I get a light out of it?

    HAH!

    Just a thought - has the design of AA batteries changed? I am wondering if a modern AA battery does not make contact in the way that the old ones did?
    Last edited by Andrew Craig-Bennett; 04-24-2018 at 05:38 PM.
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    Default

    As far as I know aa is still aa. Hopefully Mr Cooke still has your old one.


    Sent from my iPhone using Tapatalk

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    AA batteries sort of look the same as they used to, but they sure don't hold their juices the way they used to. I've had a few items ruined in recent years from a once reliable brand of batteries... I use a different brand now.

    Is that artificial horizon you mention the same thing as a bubble sextant? Is it ok on a small boat or was your sextant only for use on ships?

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    A sex wha ?

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Small boats rock View Post
    AA batteries sort of look the same as they used to, but they sure don't hold their juices the way they used to. I've had a few items ruined in recent years from a once reliable brand of batteries... I use a different brand now.

    Is that artificial horizon you mention the same thing as a bubble sextant? Is it ok on a small boat or was your sextant only for use on ships?
    It's different to the WW2 bomber's "bubble sextant". It screws onto the telescope mount and there is a tuning knob that varies the size of the bubble; get your star in the middle of it and there you are. I found it quite easy to use. Full description here:

    https://sextantbook.com/2012/06/26/c...on-attachment/
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Phil Y View Post
    As far as I know aa is still aa. Hopefully Mr Cooke still has your old one.


    Sent from my iPhone using Tapatalk
    B. Cooke are a wonderful old firm. I sent them a message on their contact form and got this reply in five minutes:

    Hi Andrew,

    Yes, the Sextant is still with us. Please call with card details tomorrow, £. 16.50 + Vat Post & packing
    We can send back to you tomorrow and you will have it back on Friday.

    Best Wishes,
    Priyanka

    Priyanka Perera BSc (Hons) MBA CMgr FCMI
    Managing Director
    B. Cooke & Son Ltd.
    "Kingston Observatory"
    58-59 Market Place,
    Hull HU1 1RH
    UK
    Phone: +44 (0)1482 223454
    Fax: + 44 (0) 1482 219793
    Mobile: + 44 (0) 7590 204644
    Company Registration 224604 Vat GB167865905
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Andrew, I was taught that artificial horizons are totally unsuitable for use on a rolling boat deck. My own attempts with an aircraft sextant seemed to verify this. Is this artificial horizon something new? I say "new", but I must admit that it's been 30 years since I've needed a sextant to figure out where I was.

    How does it work?
    Electronic?
    Not affected by acceleration?

    You have piqued my interest!!!

    -------------------------------

    Sorry, nevermind, I didn't notice the link at the end of your post. I'll read up on it. Thanks!
    Schooner captains love to get blown offshore!

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    I'll post a picture when I've got it back. It is different to the aircraft type, in that the bubble seems to be stabilised in some way, but frankly it is "more usable" in quieter conditions.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Okay. I read the article in your link. From the first graph.

    I have placed this post in the Aircraft bubble sextant category because, although the C Plath bubble horizon instructions imply that it can be used at sea with a nautical sextant, this is not the case. Bubble horizons are of use on land and in the air, where accelerations either do not occur or occur in a well-understood way. However, accelerations at sea are too great and unpredictable for them to be useful, except perhaps on a very large vessel in calm waters or in ice where no horizon is visible.
    This is as far as I got.

    I've got a sextant app for my smartphone. It's really neat, and I suspect that it's quite accurate, and it's totally useless for navigation. There is just no way to accurately point it, even while sitting comfortably in your living room. I suspect that an electronic device with an accelerometer and software capable of compensating for Coriolis Effect is on the horizon...so to speak!
    Schooner captains love to get blown offshore!

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by SchoonerRat View Post
    Okay. I read the article in your link. From the first graph.

    This is as far as I got.

    I've got a sextant app for my smartphone. It's really neat, and I suspect that it's quite accurate, and it's totally useless for navigation. There is just no way to accurately point it, even while sitting comfortably in your living room. I suspect that an electronic device with an accelerometer and software capable of compensating for Coriolis Effect is on the horizon...so to speak!
    The nautical use of a bubble horizon sextant (aside from establishing the position of your back garden, for practice) is when you have calm conditions but no usable horizon.

    As the article says, the "classic" use is in ice, but it is also usable when you have the sun, but you also have fog. This is not uncommon in the waters where I usually sail, and before GPS (Thank you, tax paying Americans!) I did sometimes use it in that way - on one occasion, standing into the Thames estuary from Holland, I got a brief glimpse of a buoy, but it vanished before I could read it, and a Sumner line - I'd like to claim that it passed through the buoy but of course it didn't! It did permit an "educated guess", though, and a glance at the echosounder helped, as well.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    So, I am interested in old things... but also embrace new.

    With that in mind... and because I am not sure exactly what this particular handle looks like, would it be possible to have one made on a 3D printer?
    Heute ist so ein schŲne Tag...

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Andrew Craig-Bennett View Post
    .......

    - on one occasion, standing into the Thames estuary from Holland, I got a brief glimpse of a buoy, but it vanished before I could read it, and a Sumner line - I'd like to claim that it passed through the buoy but of course it didn't! It did permit an "educated guess", though, and a glance at the echosounder helped, as well.
    also coming into the thames estuary from an overnight from the netherlands, about thirty years ago in a lovely 27ft mahogany motor cruiser with a big old ford 6 cyl diesel, the skipper called out 'get up for'ard we should be coming up to such n such buoy any minute.. can't see a bleedin thing' ...

    .foggy to thirty metres or so, couldn't see a thing either, and then looming up and dead in front ..' Buoy ! Buoy!
    BANG we hit it dead on . Skipper's comment..'I always thought navigation ws one of my strong points'
    'C'est la vie' say the old folks it goes to show you never can tell

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by jonboy View Post
    also coming into the thames estuary from an overnight from the netherlands, about thirty years ago in a lovely 27ft mahogany motor cruiser with a big old ford 6 cyl diesel, the skipper called out 'get up for'ard we should be coming up to such n such buoy any minute.. can't see a bleedin thing' ...

    .foggy to thirty metres or so, couldn't see a thing either, and then looming up and dead in front ..' Buoy ! Buoy!
    BANG we hit it dead on . Skipper's comment..'I always thought navigation ws one of my strong points'
    The Thames Estuary “Classic”! See the Foreword to Mary Blewitt’s “Celestial Navigation for Yachtsmen” for another example of the same thing!
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Andrew Craig-Bennett View Post
    B. Cooke are a wonderful old firm. I sent them a message on their contact form and got this reply in five minutes:

    Hi Andrew,

    Yes, the Sextant is still with us. Please call with card details tomorrow, £. 16.50 + Vat Post & packing
    We can send back to you tomorrow and you will have it back on Friday.

    Best Wishes,
    Priyanka

    Priyanka Perera BSc (Hons) MBA CMgr FCMI
    Managing Director
    B. Cooke & Son Ltd.
    "Kingston Observatory"
    58-59 Market Place,
    Hull HU1 1RH
    UK
    Phone: +44 (0)1482 223454
    Fax: + 44 (0) 1482 219793
    Mobile: + 44 (0) 7590 204644
    Company Registration 224604 Vat GB167865905
    Wonderful

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Exhibit A: C. Plath ladder frame micrometer sextant no. 40128, with C.Plath 6x30 prismatic monocular shipped.



    The 6x30 prismatic was apparently popular with submarine navigators in WW2 (USN and Kriegsmarine, independently) because, they said, you could get a horizon for a star sight, using one, after and before nautical twilight. I’ve never tried, but it is a jolly nice telescope.

    Exhibit B: C.Plath ladder frame micrometer sextant no. 58465, with C. Plath artificial horizon no. 2166 shipped.



    You need to hold down the light switch, and if you do you will see a bubble floating in a soft red background and the trick is to get the star in the middle of the bubble.
    Last edited by Andrew Craig-Bennett; 04-29-2018 at 03:20 PM.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Oddly enough these two are not as identical as they appear to be.

    One has an aluminium frame and one has a brass frame, the means of securing the shades is different, the handles are different, the means of securing the index mirror carrier casting to the index bar is different and I bet the pivot is different too, (but I have no plans to find out). The means of adjusting the mirrors is not the same either; the top one uses a little hexagonal wrench and the bottom one uses a 1.5mm Allen key. And the electric system is slightly different.

    What is truly bizarre is that both have Certificates, from different places at different dates, which show the same small errors.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Andrew Craig-Bennett View Post
    The Thames Estuary “Classic”! See the Foreword to Mary Blewitt’s “Celestial Navigation for Yachtsmen” for another example of the same thing!
    You had me worried for a moment...I thought I was having premature senior moment in that I have the Blewitt navigation and shot off to the library (well the boatbookshelf anyway) to see if I hadn't actually experienced it but had read about it and it had gone into the fog of urban myth and apocraphy.
    hey presto I don't have celestial navigation but Mary Blewitt's 'Navigation for Yachtsmen' and its not in there.

    For years I thought my earliest memory was me sitting on a blanket as a maybe two year old...very strong image, only to come across a photo, clearing out after my Ma died 50 years later,. of just that image. Not mine at all and my mental image was of me sitting on the lawn from the camera point of view.... never dawned on me It obviously couldn't be so.
    'C'est la vie' say the old folks it goes to show you never can tell

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    AA batteries have stayed the same size as far as I can tell. Quality and capacity of modern AA batteries varies widely, though. Heck some are even lithium now. Different chemistries will produce slightly different voltages. Most gear shouldn't notice the difference.

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by marujo.sortudo View Post
    AA batteries have stayed the same size as far as I can tell. Quality and capacity of modern AA batteries varies widely, though. Heck some are even lithium now. Different chemistries will produce slightly different voltages. Most gear shouldn't notice the difference.
    Its actually the construction of the case. I noticed that the spring that holds the batteries in contact was of a diameter which contacts the outer edges of the case - fine for a 1960s zinc case carbon pole battery but won’t work with a modern one, so I tweaked the spring to make it contact the centre of the base of the battery!
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    And the result of tweaking the spring was that it now works?

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    AH, that makes sense.

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Small boats rock View Post
    And the result of tweaking the spring was that it now works?
    The result of tweaking the spring was that I discovered that the wire had broken.

    "These things are sent to try us!"
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Like other small specialised firms*, C. Plath, Hamburg, nautical instrument makers, had a serial number system that must have made some sense to someone, sometime.

    As Disraeli said of the Schleswig Holstein Question "There were once three people who understood this - the Prince Consort, an elderly German professor and I. The Prince Consort is dead, the professor is in an insane asylum .. and I have forgotten it!"

    * see, eg, Henry Browne and Sons, Barking, as in "Sestrel" Compasses, or, for that matter, Mercian Cycles...
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    I'm thinking maybe you should advertise as a sextant repair specialist. Glad you've got at least one working.

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Quote Originally Posted by Small boats rock View Post
    I'm thinking maybe you should advertise as a sextant repair specialist. Glad you've got at least one working.
    I hardly think so!

    There is an expert, Dr Morris, who has indeed "written the book on it" - but he lives in New Zealand.

    I recommend both his book and the associated blog:

    https://sextantbook.com/

    Oh, and whilst I am here, I'll just continue my Plath rant...

    There's every reason to think that Tamaya and Plath were great mates, certainly down to 1945, given the uncanny similarities of the sextants they were both making (very similar frames, micrometers, telescopes, rising pieces) but why did Plath go in for some downright (expletive deleted) practices such as the way that their telescopes are held in their cases, and come to that the way their sextants are held in their cases, etc after WW2?
    Last edited by Andrew Craig-Bennett; 05-04-2018 at 01:28 PM.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Thanks, Andrew , for the chance to read something about sextants and think about them. I first learned celestial navigation self-taught while in the US Navy on nuclear submarines. Yes, we had a sextant-just in case... Later, being a small boat sailor planning to do some world cruises I got my first Hezzanith and this turned out to be my "ticket". Being the guy around who could navigate I got invited on many a cruise: Bermuda, Carribean, across the Pacific and all and later I morphed into a Captain of all sorts of Oceanographic Research Vessels going everywhere. Later actualy found myself chasing Sir Ernest Shackleton re-enacting some of his voyages (Worsley was my man!) But similarly, as an airplane pilot as well, I got interested in the mystery of Amelia Earhart and Fred Noonan's loss and in order to help understand it got myself a bubble sextant and an Astro Compass from the Pre-WW2 period and tried them. Anyone who studies those epics (Shackleton/Worsley and Earhart/ Noonan) will learn that the navigators were TOP NOTCH. Noonan was the best arguably of his time, a pioneer. I did learn though that securing a sight in the bubble sextant at altidude and in flight was not easy. I did not get the sense of recognizing a good "snap" as I do with the marine sextant. Also the bubble sextants evolved to include mechanisms with recording devices which would allow the navigator to mechanically average a set (10)of sights. At 150 knots a mile or two or five accuracy is often good enough. I still enjoy the practice. Cheers/ JC

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    A small mystery; a well known auction site is absolutely awash with Indian fake sextants, but perfectly good sextants in well used and tatty condition (which you or I would buy immediately!) attract little interest, and sell for much the same price. At least this stops peasants from trying to polish the real ones, I suppose.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Did you know that a Tamaya telescope fits a Plath and vice versa?

    I very strongly suspect that an Astra telescope will fit both, because it looks to me as if Tamaya copied Plath and Astra copied Tamaya.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    I wonder which copy ended up being the best?

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    I find the modern Astra IIIB to be very easy to use. It's light, and I do like the full view horizon glass. The frame of the sextant is Plath's WW2 design - which they dropped after the war and went back to the ladder frame - both of which Tamaya also used. The layout is Plath-style. The micrometer is easy to read and the quick release screws are better than Plath's. You would need a collimator, in the hands of a knowledgeable user, to assess the build quality of each, so I can't speak to that. In favour of the Plath is their outstanding 6 x 30 prismatic scope (which I strongly suspect was actually made for them by Zeiss - nuff said!)
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Poking about on Dr Morris' blog page, I found this gem. Start at page 37 :

    http://fer3.com/arc/imgx/Commentary-...e-Ramsdens.pdf

    Jesse Ramsden ought to be "up there" with William Harrison and James Cook. I had always thought that Henry Maudslay had made the first screw cutting lathe, because that is what all histories of the Industrial Revolution will tell you. I was wrong.
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    A bit more ranting about C. Plath.

    I have been starting to suspect that their 6x30 prismatic monocular (which is brilliant!) was made by Zeiss, and not as a sextant monocular.

    The Tamaya 7 x 35 monocular, much favoured by Japanese submarine navigators in the course of the Late Unpleasantness in the Pacific*, has the rising piece cast into the telescope body. A nice way to do it. Plath on the other hand made a two part rising piece by soldering together two bits of bronze, and then screwed this onto the thin aluminium body of the monocular. A horrid way to do it.

    In a spirit of enquiry, I bought an East German Zeiss 6 x 30 monocular on ebay.. and guess what - it's a clone of the one on my Plath, save that the latter does not identify itself as made by Zeiss Jena.

    Thinking back to the days of my youth working for a very eminent Hamburg salvage tug company, I recall that there was an absolutely roaring barter trade always going on between east and west...

    hmmm

    Anyway, I am going to get Classic Marine to cast a nice rising piece or two in bronze, using the original one as a pattern... anyone want one? Zeiss 6x30 monoculars are not rare...

    My Tamaya was certified in January 1945 and spent a very long career in the P&O Steam Navigation Company. Still works; weighs a ton...
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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    Hi Andrew,

    I had the same problem with a Plath I bought recently, and found that it worked if you put the batteries in with the negative end first. I think the battery design has changed since the sixties, with the hole outer skin, under the plastic, now positive. The spring in the screw cap contacts the plastic, and if you remove this, it's positive at both ends. With positive down, the brass srew in the cap contacts the battery, and the light works. Also check all contacts, and the connection of the wire to the little plug. Finally, make sure you use the correct switch (there are two).

    Best regards, Jaap.

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    Default Re: Donít mind me; I just need a small rant... C. Plath sextant battery issues.

    I've used a sextant quite a bit but have never understood the point of a battery. I presume it's to take readings off the scale, but if it were that dark one would also need a dim flashlight/torch to read the time and jot down the results. Why would you need a separate light source for the sextant that introduces weight and possible corrosion.

    An aside: I was taking sights one evening and handed a crewmate my watch. I said "when I say mark, you tell me what time it is". I duly brought the star to the horizon, said "mark" and she said "it's just about a quarter of seven".

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