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
    Name or NavList Code:
    Re: Relative bearings
    From: Greg Rudzinski
    Date: 2015 Apr 14, 15:37 -0700


    When working with true and magnetic bearings to be plotted on a chart you will be using the pelorus 0° clockwise to 360°.  If doubling the angle on the bow or using Bowditch table 7 (1981)/table 18 (2002) then work port and statboard off the bow or stern. There is also the radian rule which is worked port and starboard off the bow. see link:


    Greg Rudzinski

    From: Bill B
    Date: 2015 Apr 14, 14:34 -0700

    Recently viewed a page at the URL below and it struck me as vague and misleading regarding "relative bearing" and pelorus use:


    I've always regarded relative bearing (RB) as a 0-360d measurement with the bow-end of the lubber line being O. The above article seems to suggest it is always measured 0-180 CW on the starboard side and 0-180 CCW on the starboard side. Also that a pelorus card is always set to 0.

    I consider RB starboard and RB port to be a subset of RB. Borrowing from submariner terminology it makes communications/notations easier for me to use "Angle of the bow" or "AOB" noting port or starboard when necessary.

    My calculations use the following (True bearing = TB, compass = C)

    AOB or RB starboard = RB

    AOB or RB port = 360 - RB

    RB = TB + C

    TB = RB-C

    C = RB - TB

    Add or subtract 360 if less than 0 or greater than 360 respectively.

    Any opinions on standard usage of RB and AOB?

    Browse Files

    Drop Files


    What is NavList?

    Get a NavList ID Code

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

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

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

    Email Settings

    NavList ID 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