NavList:

   

Reply

Ridge,
I 100% agree with your opinion.
Some sextants have a vernier (on the 1' drum) reading to 0'2.
Astra, if I remember correctly, and many British sextants.
I think 1' drum with no vernier is sufficient for all purposes
a sextant is used in XX century:-)

BTW, speed and certainty of reading is also very important.
And on my opinion, vernier/drum combination INCREASES the
chance of blunders. (From my experience with Bill B. Astra).

But a magnifier is great for twilight and for the Lunars:-)

Alex.



> Given the likelihood that no sextant can repeat a reading down to one
> tenth
> of a minute because of tiny amounts of "slop" between the tangent screw
> and
> the limb, vernier scales strike us as maybe desirable - but by no means
> necessary - for accuracy.
>
> Just one man's opinion. Anyone else have thoughts on this?
>
> Ridge White
>
> Robert E. White Instruments
> PO Box 775
> Medfield, MA 02052
>
> Tel: 617-482-8460
> Fax: 617-482-8304
>
>
> On Mon, Aug 13, 2012 at 11:33 AM, Jeremy C  wrote:
>
>> Hi All,
>>
>> I just took a ship from Anchorage Alaska to Singapore. She had onboard a
>> Freiberger sextant, the first I had seen or used.
>>
>> Here's a photo: http://www.flickr.com/photos/37977699@N00/7774059416/
>>
>> I can't say that I was too impressed to be honest. It was fairly light,
>> being all Aluminum, and the shades were nice. The unit was also well
>> constructed and the movement of the arm and micrometer drum were silky
>> smooth. Still the non-standard fork precluded the use of my 7x35 scope
>> which was unfortunate.
>>
>> The biggest thing that bothered me was that the micrometer drum had me
>> interpolate within 1' incriments. For a Lunarian, this is quite
>> unacceptable. I want to interpolate at 0.1' or 0.2'.
>>
>> The weather on the 21 day trip was terrible for stars and shooting in
>> general for my whole trip. I did manage a few sun lines which worked out
>> well, but no stars. I will say that shooting at 60 deg N made this the
>> closest to the pole I've ever shot. It's just too bad there was no
>> chance
>> to shoot a round of stars up there.
>>
>> Sadly the ship, MV VIRGINIAN, along with the sextant, will be on the
>> beach
>> being turned into razor blades in a few weeks, as the owners decided to
>> sell it for scrap. So much for my second command. I guess that's the way
>> of
>> the shipping world.
>>
>> Jeremy
>> ----------------------------------------------------------------
>> NavList message boards and member settings: www.fer3.com/NavList
>> Members may optionally receive posts by email.
>> To cancel email delivery, send a message to NoMail[at]fer3.com
>> ----------------------------------------------------------------
>>
>
>
>
>
> : http://fer3.com/arc/m2.aspx?i=120339
>
>
>

   

Reply