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: Summary of Bowditch Table 15
    From: Bill B
    Date: 2005 Jan 25, 18:03 -0500

    > Using the simplified formula for distance to horizon, 1.169(sqrt height of
    > eye) the observer's horizon would be 9.8 nm away.  If the observed vessel is
    > 5 nm away, as stated above, the observer should be able to see the hull and
    > waterline, in which case Table 16 would apply.  (Note that the geographical
    > range would be 21.5 nm from 70 ft aloft.)
    Getting down to short strokes, I am assuming 100 ft of mast visible above
    the deck (as opposed to a 100 ft mast keel stepped, showing maybe 92 ft
    above deck).
    In reality, a sailboat large enough to sport a 100 ft stick above deck would
    probably have a deck at least 6 ft above the waterline at the mast.
    Therefore, geographical range (at 10 ft observer height of eye) of the
    mast's base would be approx. 6.6 nm, more than enough to see the entire mast
    at 5 nm.
    Is the devil indeed in the details? ;-)

    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