Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Bubble horizon
    From: Robert Eno
    Date: 2002 Dec 16, 18:32 -0500

    I'd like to add my two bits' worth on this topic because I have worked with
    bubble horizons for quite a few years.
    In my experience, the greatest cause of errors, vis a vis bubble attachments
    is due to inherent design flaws.
    To make a long story short, unless you can adjust the size of the bubble,
    you will experience errors; sometimes gross errors. Several years ago, I had
    an opportunity to take dozens of sights with a very expensive ($1000 US)
    professional bubble attachment made by a well-known sextant manufacturer.
    This bubble attachment did not have a provision for adjusting the size of
    the bubble. In my estimation, it was not worth the price. It appears to me,
    anyway, that a practice bubble horizon will produce the same results as the
    very expensive "professional" attachment. Save your money.
    Contrast this to a C.Plath bubble attachment which does have a provision for
    adjusting the size of the bubble. One can obtain very accurate positioning
    data when using this device. Unfortunately, they are relics of the past. I
    don't think that they have been manufactured since the early 1960's but are
    still available from time to time, from antique and used sextant dealers.
    According to one publication that I have, they were issued to U.S. Navy
    fleet ballistic missile subs as a backup. Can't verify that first-hand
    though so take this with a grain of salt.
    Finally, as far as bubble sextants/bubble attachments are concerned, the
    best, the most accurate and the easiest to use, ever, is the RAE Mark IX
    aircraft sextant. It wins hands down in all categories.
    ----- Original Message -----
    From: Marc Bernstein 
    Sent: Monday, December 16, 2002 3:49 PM
    Subject: Bubble horizon
    > I assume most of us are using the "practice bubble horizon" sold by
    > Celestaire. The key word here is 'practice'. It is not particularly easy
    > sight through and the bubble is quite wobbly. The main problem appears to
    > a lack of fluid dampening. Based upon my experience 7 minutes is not bad.
    > often get accuracies of 10-15 minutes. Maybe I need more practice.
    > By the way if you hold a flashlight in just the right spot, it is possible
    > to illuminate the bubble from the outside so you can use the practice
    > at night also. This only works with the Moon. There is not enough light
    > transmission to sight a star, and no magnification.
    > But for those of us who are landlocked it is still worth it.

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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