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: Level of observation accuracy in medium seas
    From: Dave Weilacher
    Date: 2004 Jul 22, 16:28 -0500

    An experienced navigator should be able to determine he was in or near lake 
    michigan during daylight hours (and if he was hungry, that would indicate 
    somewhere around noon or American)
    
    
    
    -----Original Message-----
    From: Bill 
    Sent: Jul 22, 2004 4:13 PM
    To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    Subject: Level of observation accuracy in medium seas
    
    Had a chance to make my first "on water" observations last weekend.
    
    First sun shot was from the pier using short dip and was right on the money
    (according to GPS fix).  Better lucky than good ;-)
    
    Second was a bit more challenging.
    
    Location: Lake Michigan near Michigan City (southern end of the lake).
    Boat: 34' Catalina fin keel with tall rig (36' Catalina mast and sails)
    
    Day before on the water:
    
    * Wind out of the north (started 005d and backed to 340d)
    
    * Started at 12-18 kn, end of day 18-23 with puffs to 28+ (true, not
    apparent).  Headsail at 110, 1 reef in main.
    
    * 4-6 foot confused seas.  By day's end waves in the 8 foot range were
    forming.
    
    Day of shoot:
    
    * Wind still out of the north (started 005d and backed to 340d again)
    
    * 10-15 kn true, puffs to 19+. 150-130 headsail, full main.
    
    * 3-5 foot confused seas.  By day's end waves in the 6 foot range were
    forming.
    
    * Course 274 true (just above beam reach). Heel 12-22 degrees.
    
    * Slight haze, visibility approx. 15 nm.
    
    *  Approx. 8 nm off southern shore so had the horizon backed by sand dunes.
    
    Did a noon sun shoot within seconds of local noon with 0 magnification sight
    tube.
    
    Question:
    
    What degree of accuracy (range?) would an experienced sextant operator
    expect under these conditions:
    1. With 0 magnification sighting tube
    2. With 4X telescope
    
    
    Dave Weilacher
    .US Coast Guard licensed captain
    .    #889968
    .ASA instructor evaluator and celestial
    .    navigation instructor #990800
    .IBM AS400 RPG contract programmer
    
    
    

       
    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