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    Re: Dream Choice of Sextant
    From: John Simmonds
    Date: 2005 Aug 9, 00:27 +1000
    biggest problem with stainless steels is cost of manufacture, and don't kid yourself that it would be corrosion free :)
    the thing would also be very heavy
    John
    live every day like it may be your last .. cause one day it will be


    On Mon, 8 Aug 2005 07:39:51 -0400, Robert Eno wrote:
    > I know my choice lies outside the bounds of what you described but
    > my dream choice of sextant would be a C.Plath design in which all
    > of the components are constructed from 316 stainless steel. I often
    > wonder why no one ever thought of using this material for a
    > sextant. Perhaps because it cannot be cast or perhaps because
    > stainless steel is more prone to thermal changes than bronze or
    > brass.
    >
    > Robert
    >
    >
    > ----- Original Message -----
    > From: "Mike Hannibal" <pelorus32{at}YAHOO.COM.AU>
    > To: <NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM>
    > Sent: Monday, August 08, 2005 2:43 AM
    > Subject: Dream Choice of Sextant
    >
    >
    >> If you had a choice between a C&P Horizon Ultra and a
    >> C&P Pelorus which would you choose? Money isn't the
    >> issue.
    >>
    >> The use is the full breadth of uses to which you might put a
    >> sextant with an equal balance between
    >> star/planet sights, sun sights and coastal nav stuff - distance
    >> off, horizontal bearing etc.
    >>
    >> For those unfamiliar the key differences between the
    >> two instruments are:
    >>
    >> 1) both use the same frame and "running gear";
    >>
    >> 2) the Horizon Ultra has a whole horizon mirror,
    >> polarisers in both sets of shade glasses and
    >> Schueler's double prism to get verticality right. In
    >> other words it's a specialist sun machine;
    >>
    >> 3) the Pelorus has standard shades, an astigmatiser
    >> for stars and planets, and an unusual horizon mirror
    >> that is about 70% silvered in the a centre vertical
    >> strip and unsilvered on either side. It is designed to be very
    >> effective with dim stars but still OK brighter objects.
    >>
    >> I guess my current thinking is that the polarisers are nice and
    >> make sun brightness and horizon clarity very easy to get just
    >> right but that the Polaris is
    >> proabably better for stars as it isn't hampered by the known
    >> issues of a whole horizon mirror. On balance what I want is the
    >> Pelorus with the polarisers as
    >> well. I expect that verticality of the instrument will not be an
    >> issue when using the astigmatiser but that
    >> you'll just have to rock like you always do when doing sun/moon.
    >>
    >> Love to hear your views, and particularly if anyone
    >> has used the Polaris or the Horizon Ultra.
    >>
    >> Regards
    >>
    >> Pelorus
    >>
    >> Send instant messages to your online friends
    >> http://au.messenger.yahoo.com

       
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