Announcement

Collapse
No announcement yet.

Does Celestial Navigation still have a role in navigation despite the use of digital methods?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Does Celestial Navigation still have a role in navigation despite the use of digital methods?

    Hey,

    I have no doubt this topic has been discussed somewhere on here before, but as part of my final years study I am carrying out a research project into the role of celestial navigation on board modern merchant vessels. Part of my research includes a questionnaire, a link to which is below. I would be greatful if people could take the time to fill it out the questionnaire, and if possible pass it along to officers they may know, especially people with more experience, perhaps people with pre-GPS experience.

    http://freeonlinesurveys.com/s.asp?s...q6i4kob5419748


    Also what is everyones opinion, could you see a day when a ship will no longer carry a sextant and it is removed from training programmes, or do you feel it is still a vital secondary system.

  • #2
    I've never seen it used on a ship for "actual" navigation however it doesn't cost anything to keep up and running and in the unlikely event every other position fixing method broke down at once, we could still use it, so I don't see the point in getting rid of it.

    Comment


    • #3
      Only real reason I use it these days is to teach Cadets, which I enjoy.

      I do occasionally do a hand written full compass error instead of using NavPac just for memory.

      Comment


      • #4
        Does it still have a place? Yes very much so, particularly if you understand the technology and limitations behind the primary means of position fixing which is satellite navigation. Once satellite navigation is unavailable, your options are limited deep sea.
        Will sextants still be a requirement on ships and will celestial still form a part of the syllabus in the future? Probably not.

        Comment


        • #5
          In the early days of GPS one of our ships was crossing the Atlantic and the GPS went into DR mode, no one knew this and while doing a celestial observation one of the officers reported the position quite a way off course. This was discarded as rubbish by the Captain, but on successive days to prove a point the deck officers continued the celestial observations and they continued to increase in difference to the GPS. When they made landfall they realised the celestial observations were correct and the GPS was at fault. Hence we are required to practice celestial navigation on a weekly basis. Granted this is more often than not take a sight and plug it into Navpac, but the point is the observation will be right, there is no electronics to go wrong or be jammed. I have an uphill battle trying to convince my officers that accuracy is relative!! 5 miles deep sea is nothing, having the conviction that you know where we are is another matter entirely!?
          If you can't laugh, you shouldn't have joined!!

          Comment


          • #6
            Our one and only gyro started behaving erratically on passage from Cape Town to Singapore last trip and we were actually taking stars to double check what was going on with it as the ship had been in West Africa for years and the last magnetic compass swing was as reliable as you would imagine from West Africa.
            Go out, do stuff

            Comment


            • #7
              Thanks for all the responses and comments so far.

              Do any of you agree with a comment I received on another similar forum? A guy pointed out that looking at modern ships with totally enclosed bridge wings it makes taking sights impossible without the OOW leaving the bridge, he pointed out that it already shows designers and companies moving away from the use of celestial navigation.

              I doubt it is a conscious decision but it does mean officers cannot practice during any quiet watches.

              My last ship had open bridge wings but two small shelters on either bridge wing, above the control consoles blocked the view of about a third of the sky from the compass repeater, meaning on nights where only a few stars were visible or low enough compass errors were impossible. Has anyone else experienced this? Or seen a solution designers or companies have got to ensure we can do a compass error every watch, weather permitting.

              Comment


              • #8
                I have sailed on a passenger vessel where it was impossible to take a sight from the bridge or bridge deck, although you could go several decks up to a passenger area and use a repeater...
                On most of the large yachts, nope you won't be taking a celestial sight.

                I am in a great position at the moment that I work on a ship where I get to teach celestial navigation regularly and have a completely separate chart room where we can navigate from so that we can practice celestial fixes without the trainees unable to view a GPS position from the main bridge.

                Comment


                • #9
                  I've just spent several weeks deep sea with a couple of RN lads who came for a jolly around the atlantic to complete the sights section of their training as it is easier to do it on a MN ship than wait on the off chance that HMS whatever might actually go to sea for long enough.
                  Still that is the only time they will calculate it out by hand every other time it will be navpac. still it was good fun watching them taking sights while enjoying sundowners
                  you can take it with a pinch of salt, but i prefer it with a nip of whisky

                  Comment


                  • #10
                    My last ship you couldn't really take a decent sight because of enclosed Bridge Wings. The cadets use to take a VHF and go up the monkey island.

                    Comment


                    • #11
                      we too had some RN chaps, (mostly chapettes actually), but I must say, they aren't learning Astro-Nav as I would call it, they basically come out to use the sextant, then punch the numbers into NavPac, et voila, a position. To be fair, the majority of them do take an interest in doing it the 'proper' way, but it is the general attitude of reliance on GPS, or computers to calculate sights, that will eventually result in the phasing out of astro-nav as a subject at college.

                      Comment


                      • #12
                        it is the interesting idea that you could actually build a 'digital' sextant in that it could be gyro stabilized and then its just a simple feed of the log and compass to get a DR and it will then have everything that Navpac uses but with a much higher accuracy as it would be able to take a huge sample of sights to average them out.
                        you can take it with a pinch of salt, but i prefer it with a nip of whisky

                        Comment


                        • #13
                          Automated celestial navigation systems have existed since the 1960s, mostly for military applications. Look up "stellar inertial navigation" for more info.

                          Comment


                          • #14
                            Originally posted by Tony View Post
                            Or seen a solution designers or companies have got to ensure we can do a compass error every watch, weather permitting.
                            Compass repeater on the bridge roof.

                            Comment


                            • #15
                              Originally posted by ETwhat? View Post
                              Still that is the only time they will calculate it out by hand every other time it will be navpac.
                              Originally posted by condeh View Post
                              we too had some RN chaps, (mostly chapettes actually), but I must say, they aren't learning Astro-Nav as I would call it, they basically come out to use the sextant, then punch the numbers into NavPac, et voila, a position.
                              The RN don't teach use of the Nautical Almanac at OOW level, but it does feature in the syllabus of their advanced navigation courses.

                              Comment

                              Working...
                              X