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: Dip from Shore
    From: Gary LaPook
    Date: 2016 Feb 10, 01:16 +0000
    Shoot latitude lines since they are inherently more accurate than longitude lines. It is hard to get the time more accurate than 1 second which makes a .25 NM error band. then the published GHA is rounded to 0.1' accuracy adding another 0.1' uncertainty. Then the "increments" table also has that same 0.1' round off. If you use the GPS  position as your AP to just a 0.1' precision then you get another 0.1' uncertainty. If shooting a star then add an additional 0.1' for the SHA and if shooting a planet then you get a 0.1' uncertainty from the "v" correction (actually a bit larger since you do a multiplication step in determining the "v" correction.)
    Much less uncertainty with latitude sights.

    gl


    From: Jim Rives <NoReply_JimRives@fer3.com>
    To: garylapook---.net
    Sent: Tuesday, February 9, 2016 11:23 AM
    Subject: [NavList] Re: Dip from Shore

    I hadn't even considered wave height.  One of my future (ie, ain't gonna ever happen) projects would be to run multiple iterations of a sight reduction program, a round of say 4 or 5 well placed objects, and just increment the dip by 1 foot each round to see if the fix closes in on the real height of eye.  
    The odd thing I've noticed since recently trying to get back into taking sights is how similar snagging just the right time to "mark" is to deciding when to actually pull the trigger in shooting a target rifle.  It seems to become less of a physical thing and more of a feeling.  Probably becomes second nature.... I used to shoot probably a dozen shots a day while at sea and never gave it a thought.   
    Jim 


       
    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