NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant on ebay
From: Bill B
Date: 2006 Sep 6, 01:53 -0500
Gentlemen
If I recall, Alex's SNO-T (T for tropical?) is painted a light (metallic?)
gray to reduce heat absorption. Some manufacturers offer white "tropical"
models if memory serves.
I am not clear 0.005" to 0.010" of paint is a great insulator, therefore
markedly reducing heat transfer to one's digits. Especially as one hand
grips the handle while the other tweaks the drum.
Bill
> Red wrote:
>
>> "it is not often that you see a polished metal sextant. " Probably
>> because it is greatly impractical. In the noon sunlight, it would burn
>> your hands (bare metal) and blind you from glare spots.
>
>
> Why would a highly reflectent polished surface get hotter than one that
> is painted black? In fact, Plath tried to find a compromise between
> reducing heat absorption and avoiding glare spots with a model that was
> painted white.
>
> Herbert Prinz
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From: Bill B
Date: 2006 Sep 6, 01:53 -0500
Gentlemen
If I recall, Alex's SNO-T (T for tropical?) is painted a light (metallic?)
gray to reduce heat absorption. Some manufacturers offer white "tropical"
models if memory serves.
I am not clear 0.005" to 0.010" of paint is a great insulator, therefore
markedly reducing heat transfer to one's digits. Especially as one hand
grips the handle while the other tweaks the drum.
Bill
> Red wrote:
>
>> "it is not often that you see a polished metal sextant. " Probably
>> because it is greatly impractical. In the noon sunlight, it would burn
>> your hands (bare metal) and blind you from glare spots.
>
>
> Why would a highly reflectent polished surface get hotter than one that
> is painted black? In fact, Plath tried to find a compromise between
> reducing heat absorption and avoiding glare spots with a model that was
> painted white.
>
> Herbert Prinz
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---