Next message: Michael Dorl: "Re: Averaging"
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.
Alex.
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.
>
