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From: Courtney Thomas (no email)
Date: Tue Aug 03 2004 - 10:52:25 EDT
Joel,
I have a CHO-T with the barrel enclosed tangent screw.
How do I properly gain access to the tangent screw ?
Also, what should be done to preserve rubber eye cup pliability ?
Appreciatively,
Courtney
Joel Jacobs wrote:
> Peter,
>
> The most damage that befalls a sextant is due to living in a salt
> atmosphere, particularly when used from small craft where they are subject
> to frequent spray. Salt water, left unattended will first attack the
> mirrors. The backside of the mirror's frames have a trough which collects
> more of this spray then elsewhere and this starts to erode the silvering. In
> time, it also will eat into any chrome parts, cause the paint to bubble and
> lift on the frame. It will do major damage to a sextant with an aluminium
> frame as salt water is a strong electrolyte.
>
> The prevention is to rinse the sextant in fresh water after each use,
> whether its been subjected to salt spray or not. If the sextant has its
> tangent screw encased in a barrel or cylinder like the Russian and
> Freiberger sextants make sure to run a lot of water through it which will
> keep the screw from freezing. Then of course wipe down with a soft cloth.
>>From time to time, you may also add some lubricating oil to the tangent
> screw for protection on those that are housed. This is not necessary on
> sextants with open screws. Doug Royer recommends NYOIL. Jared Sherman
> recommends DuPont Krytox. I use what I have handy which is Vaseline and
> Never Seize. The latter only on a tangent screw encased inside a barrel or
> cylinder because it does stain.
>
> Doug some time ago wrote a message which went into great detail of how he
> and others on his ship took great pains to clean their instruments and
> protect them. One of his recommendations was the use of RainX on the
> mirrors. Hopefully he saved that message and can re-send.
>
> I also would like to hear what Jim Thompson has to say. He has one of the
> most comprehensive sites on the internet devoted to CELNAV.
>
> Joel Jacobs
>
>
>
> ----- Original Message -----
> From: "Peter Fogg" <>
> To: <>
> Sent: Monday, August 02, 2004 10:45 PM
> Subject: on washing sextants
>
>
>
>>Quoting Joel Jacobs
>>..where I
>>
>>>was talking about washing a sextant after use.
>>>
>>Would Joel, or anyone else, like to go into a little detail about this
>>
> sextant washing idea?
>
>
-- s/v Mutiny Rhodes Bounty II lying Oriental, NC WDB5619
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