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: Metric Bookmark Kamal
    From: Greg Rudzinski
    Date: 2016 Mar 18, 13:01 -0700

    Fancis,

    You can use kamals for higher altitudes but the 1 centimeter per degree geometry isn't preserved on the meteric kamal. I draw the line at 12° where 1 cm per degree is good enough through the range.

    Indian Ocean pilots didn't need declinations. Latitudes were marked by knots on a string  for their personal kamals. This would have been done during visits to trading ports as an apprentice under the guidance of an experienced pilot.

    I'm sure Canopus was useful. The helmsman would have been able to steer by it with ease. Pilots would have been able to knot in the port of call based on the maximum altitude of Canopus as it passed the meridian.

    Finding the exact moment of Canopus meridian passage for the trial was done by first using the 2102-D then a phone app CN sight reduction calculator. A few iterations gets the time for an azimuth of 180°.

    Greg Rudzinski

    From: Francis Upchurch
    Date: 2016 Mar 18, 08:06 -0000

    Thanks Greg,

    Yes, I guess even 28˚ is too big for accurate kamal readings. I suppose the Arab/Indian traders were in lower latitudes.

    Do you think they knew the declination of stars such as Canopus and could work out latitude from meridian passage measurement? How did you find the exact moment of the meridian passage?

    Best wishes

    Francis

       
    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