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
    HO 211 vs. Bayless
    From: Paul Hirose
    Date: 1999 Jul 04, 12:08 EDT

    Joe Shields mentioned the version of HO 211 by Bayless.  I bought that
    book, but still prefer the table in Bowditch Vol 2 (which I assume is
    identical to the original HO 211), at least at a desk at home.
    The main advantage is the consistent arrangement of the A and B
    columns.  HO 211 always puts B in the right-hand column.  Also, the
    numbers in the B column are boldface, at least in the Bowditch
    reprint.  Bayless is less Murphy-resistant.  B can be in either
    column; you have to look at the heading.  It's clearly marked, but you
    do need to keep your wits about you, more so than with Ageton.
    HO 211 is able to keep the A and B columns always in the same places
    because it goes out to 90 degrees on the top column headings before
    "turning around".  However, the behavior of trig functions is such
    that the first and second halves of the table are mirror images.
    E.g., A of 10 deg = B of 80 deg.  Bayless takes advantage of this by
    only going to 45 degrees before turning around.  It cuts half the size
    off the table, but also forces A and B columns to swap places.
    I'm sure Ageton was aware of the redundancy in his table, but accepted
    it in the interest of reliability.  After all, it only costs 18 more
    Another complaint is that Bayless likes to omit leading digits, if
    they're identical for several entries in a row:
     Ageton     Bayless
     163322     163322
     162738       2738
     162250       2250
    Perhaps I just have a mental block, but the Bayless format is
    slower for me to absorb.
    One practical matter is that Bowditch vol. 2 is a large book and lies
    open to any page in the table.  Bayless is a small paperback and tends
    to flip closed if you let go of it.  (However, a 1940s-vintage HO 211
    for air navigation owned by a friend has the same problem.)
    For negative altitudes, the rules in Bayless are incorrect.
    I must say there are some good points to Bayless.  Tabulating only
    whole minutes simplifies the Bayless table.  Each column contains
    one complete degree.  On the other hand, Ageton only covers a half
    degree per column, since 120 entries won't fit.  If you want to
    look up, say, 16 deg 48 min, find the 18' row in the 16 deg 30'
    column.  Not hard, but I've managed to botch it.
    The Bayless table has a clean, uncluttered look compared with the many
    unneccessary dividing lines in Bowditch.
    Neither table does a good job indicating the left-hand minutes column
    goes with the top column headings and vice versa on the bottom,
    Bayless does include a method, devised by guru D.H. Sadler (of the
    Royal Observatory, I believe) for solving sights when LHA is near 90
    or 270.  HO 211 becomes very inaccurate in such circumstances.
    The Bayless table only has 1/4 the number of pages as HO 211.
    Mike Pepperday's S-Table is yet another Ageton variant.  Like Bayless,
    he eliminates redundancy by turning the table around at 45 degrees.
    His main improvement is to number the table all the way to 360
    degrees.  You can enter his table with LHA directly, instead of having
    to convert to meridian angle if LHA is more than 180.  Additional
    hand-written column headings would let you do this with the other HO
    211 variants, of course.

    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