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: Welcome Aboard! New and returning...
    From: George Brandenburg
    Date: 2011 Feb 7, 13:26 -0800

    Not that it makes any difference in this case, but in freshman physics one learns that a floating object displaces an equivalent weight of water. Since ice is roughly 10% less dense than water, an ice sheet of uniform thickness will float with about 10% of its volume above the surface of the water. This means that the effective water level is about one foot below the surface of a ten foot thick sheet of ice.
    Cheers,
    GeorgeB

    From: sjoquist.magnus---com
    Date: 7 Feb 2011 08:53

    Re horizon on sea surface covered with 4 feet of ice: On a cargo ship (where I have most of my navigational experience) where the height of eye may easily be 25 meters distance to horizon is around 10 nautical miles. At that distance 4 feet has no significance and can be neglected.
    If your height of eye is in the range where yachtsmen feel more at home (a couple of meters) you would have to be more careful, in particular watching out for ice ridges which could play a joke with you in the same manner as high swell. Why not checking with with an home made simple artificial horizon? Two (or more) observations with the horICEon and a couple with the artificial (i.e. a tin of water - double angle etc). Assuming you are not moving between the observations and that you take them more or less the same time, they should give you the same line of poition.

    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com
    ----------------------------------------------------------------

       
    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