Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: A-12 etc.
    From: Gary LaPook
    Date: 2008 Sep 04, 00:32 -0700

    
    I love my M1A.
    
    gl
    bruce hamilton wrote:
    
    >Well, I just received my second bubble sextant in the mail. It was an
    >A-12 and it looks new.  I suspect it might be a Celestaire re-build as
    >it looks so new, and regular batteries fit. I was all ready to take it
    >to work and trim the battery holders down a bit on the lathe, but I
    >won't have to.  It came with 2 working bubble sets, and the only thing
    >I  might improve is the bubble size, so I will order some Xylene later
    >this week. Any recommendations on the perfect bubble size to shoot for?
    >
    >It was overcast tonight, but I took it out and tried it a bit and peeked
    >a a few stars. I have a lot of light pollution where I live,but the
    >superimposed bubble is great.  I spent a few years being taught how to
    >line up one small round object in a bigger round object, but this
    >process doesn't leave me with ringing ears and a sore shoulder. Ah, the
    >joys of a steel butt plate.
    >
    >
    >I can see why I was cautioned about getting a bubble sextant by list
    >members. They are brilliant machines and you can't buy just one. I can
    >also make sure my apartment has not moved, just by stepping out on the
    >balcony. I did a LOP with the A10 the other evening with a sun shot a
    >half hour before sunset and was 0.87 NM from my AP, which was my actual
    >position taken from Google earth. (More luck than skill).  I figured out
    >its index error using a distant bridge.  I hope to take both of the
    >sextants down to my local surveying shop and pop them in front of the
    >horizontal collimator. The fellow in the shop seems to like madmen like
    >myself who insist on using antiques to get around in this GPS age. I was
    >fascinated to hear that they get accuracies of 2 cm with a proprietary
    >GPS system they use now.
    >
    >I would like to try a bubble sextant on a ship some day. The biggest
    >ship I ever worked on would hardly roll at all on a calm day, and even
    >less with a load of iron ore!  I used to practice sun shots on my first
    >ship, a salty little 315 foot coastal freighter, and always wondered how
    >people managed to do it on a sailboat in weather.I used to work out
    >distance off by verticle angle with any handy lighthouse, or other
    >object of known height, and found that to be quite accurate. I never did
    >much horizontal angle work, but an old classmate who is a coast guard
    >officer says they still double check all buoy positions that way.
    >
    >I had asked where Radio Direction finders went as they were the cheap
    >backup when I last pleasure sailed in the mid seventies.  I see that the
    >technology has been dropped by pleasure boaters, and can only find old
    >sets. The modern commercial sets look great and give you an instant
    >readout calculated from 4, or more antennas. No more seeking the null.
    >Hams use them too. I used the Marconi RDF on the first ship I was a
    >cadet on, and it was pretty handy when the loran-c chains were acting
    >up, and there was nothing on the radar close enough to give a good range
    >and bearing.  I have dim memories of applying some sort of corrections
    >for far away stations. The correction sheet looked like sine wave. I'll
    >have to look it up in Bowditch. It was great as you would find a strong
    >station get a bearing and there you were with a bearing and something to
    >listen to as well as it picked up many bands.  Aircraft still have ADF,
    >but like all avionics, they are pricey. The Grampion 30 that I sailed
    >from Thunder Bay Ont to Georgian Island had nice portable RDF on it. I
    >think it was the Gladding Cyclone pictured on the page below.
    >
    >
    >
    >Here's a page of old RDFs.
    >
    >http://www.angelfire.com/space/proto57/rdf.html
    >
    >
    >Here's a great article on Celestial from an airbus pilot.
    >
    >http://www.airspacemag.com/flight-today/celestial.html
    >
    >Thanks again for all the information. I enjoy reading everyone's posts.
    >
    >Other projects I have in mind. I just got 3 microscope slides so if
    >anyone has some good pages on the Briss sextant, please send it to me.
    >
    >Once Gary has recovered from his trip, I look forward to his posting the
    >information on the Byrave sextant as constructing one is going to be a
    >winter project for me. Here in Vancouver BC, we might not see the sky
    >for months on end so I need something to do other than work through
    >celestial nav examples.
    >
    >
    >Bruce Hamilton
    >Vancouver, BC
    >
    >>
    >
    >
    >
    
    
    --~--~---------~--~----~------------~-------~--~----~
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site