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    Re: Averaging sights on commercial vessels
    From: Alexandre Eremenko
    Date: 2004 Oct 7, 13:59 -0500

    Dear Doug,
    Thank you for your explanation on how Cel nav is practiced
    on modern merchant vessels.
    I suppose they took it much more seriously in the pre-GPS era
    that is 20 years ago.
    A Russian manual (for merchant mates) of early 1970 recommended
    5 observations per day if conditions permit.
    And averaging 3-5 altitudes for each observation.
    As I understand, before GPS, Cel Nav was the most precise
    available method of determining position in the open sea,
    superior to radionavigation.
    On Thu, 7 Oct 2004, Royer, Doug wrote:
    > Alex,
    > You can,for all practical reasons,discount that averaging sights are the
    > standard proceedure onboard Merchie vessels in this day and age.
    > By this I mean the duties of the nav watch are such that having this as a
    > standard proceedure is not practiced.The nav watch is more concerned with
    > navigation,chart position and collision avoidance by useing radar and
    > sonar.The nav watch  on commercial vessels usually consist of the OOD(3rd
    > officer or above), 2 but usually 1 ABS ratings on duty(all officers must
    > also be rated as ABS,so usually only 1 ABS and 1 officer are on the bridge)
    > around the bridge area and 2 S ratings on forward and/or roving
    > lookout.Conditions will dictate how many are called to nav watch duty at a
    > given time.On most merchies I doubt seriously if any celestial sights are
    > taken on a daily basis.The company I used to work for left most of the
    > operating proceedures up to the master.Some masters I've served with
    > required at least 1 sight be taken and LOGGED each 24 hrs while others had
    > no such requirement.
    > We would have training schedules for all personnel intrested in learning cel
    > nav and other aspects of navigation but these were,for the most
    > part,conducted on their off duty hours.Averaging sights is taught(especially
    > when an inexperianced member is practicing to become proficiant with the
    > equipment and reduction proceedures)and used when practical.Only if a rating
    > was rated for standing as a member of the nav watch would we have on duty
    > training in the cel nav and other disciplines so they could become
    > proficiantly skilled to meet the standards set by the company and Coast
    > Guard to advance.One was taught and trained(through repitition,trial and
    > error)to become proficiant in taking 1 cut and 1 cut only in a sighting
    > session.This takes time and practice.Not always the most accurate method
    > even by officers but duties elsewhere leave not much time while on watch
    > because of the reduced number of crew personnel onboard.The reliance on the
    > interpretation and use of electronic postion finding equipment is paramount
    > on today's merchy vessels.
    > Even though the Coast Guard requires each vessel to carry the needed
    > equipment AND have as a crew's complement people who are proficiant in
    > position finding by celestial navigation it is not practiced on a scheduled
    > daily basis throughout the industry today.It is practiced,for the most
    > part,now as a matter of professional pride for both officer and rating.
    > Joel,thanks for shareing the pictures of the Vero Beach area.That will give
    > us all a glimpse of the power,especially in the dangerous quadrant,of
    > typhons or hurricanes.

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