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  1. #1
    Join Date
    Nov 2016
    Posts
    2,636

    Default Call yourself a navigator?'



    There's a vigorous discussion within Facebook about this, between those who 'talk the talk' and those who can 'walk the walk'....
    c/f The Practical Celestial Navigation Group.

    FWIW, it's long been known that just about 'everyone and his uncle' had the capacity to jam or spoof GPS signals in an area of interest. That's been experienced time and again around UK maritime training areas, for presumed 'training and testing' of UK and NATO Services capabilities.

    The Iranians are actively jamming GPS signals at present around the Straits of Hormuz and Eastern Persian Gulf.
    .....iran-regime-is-jamming-gps-signals-in-strait-of-hormuz-to-disrupt-commercial-shipping.....
    Last edited by zoidberg; 09-08-19 at 08:24.

  2. #2
    Join Date
    Mar 2007
    Location
    Atlantic
    Posts
    21,370

    Default Re: Call yourself a navigator?'

    Always have a back up to your back up. Was drummed into my head!

    So we have two sextants and for serious off shore can print some stuff off the internet before sailing to back up the tables.

    Plus, of course, my wife can do astro.

    Win, win.

  3. #3
    Join Date
    Jul 2008
    Location
    East coast UK. Mostly. Sometimes the Philippines
    Posts
    9,812

    Default Re: Call yourself a navigator?'

    The RN Officers are both using Plath sextants!

    You can still buy “surplus” RN grey sextants.

    Plath have been out of business for a couple of decades.

    Wassup?

    (Yes, I have two Plath sextants, one that I’ve had for decades and an alloy frame one that I picked up cheap as a spare, ex German Navy, without a telescope, and which I now prefer. (The Plath 6x 30 is the East German Zeiss army monocular, if you find yourself without one...)The weak point of the Plath is the absolutely rubbish switch in the handle...)
    Last edited by Kukri; 09-08-19 at 09:35.

  4. #4
    Join Date
    Nov 2016
    Posts
    2,636

    Default Re: Call yourself a navigator?'

    I recently sold a perfect 'virgin' Freiberger Trommel sextant which had never been afloat.... at less than half list. I do have another SunGun which will see me out, but must replenish my working stock of pre-sharpened 2B IKEA pencils. My WorkMate Carpenters' Pencils aren't quite as good.....

  5. #5
    Join Date
    Jun 2007
    Location
    Home: North West, Boat: The Clyde
    Posts
    3,649

    Default Re: Call yourself a navigator?'

    This thread has had me reaching for the Yellow Page within the Almanac. Slightly surprised to see that Dip/Ht of Eye correction is listed to 48m. That’s quite a bit more than the deck of my boat!

    How high are the navigators in the video clip?

    Would a junior rating have to send a weighted line overboard to measure heigh of eye

  6. #6
    Join Date
    Jun 2013
    Location
    Hopefully somewhere warm
    Posts
    9,653

    Default Re: Call yourself a navigator?'

    Anyone here actually lost all the gps's onboard and had to resort to astro on an ocean passage?

  7. #7
    Join Date
    Jul 2008
    Location
    East coast UK. Mostly. Sometimes the Philippines
    Posts
    9,812

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by GHA View Post
    Anyone here actually lost all the gps's onboard and had to resort to astro on an ocean passage?
    I seem to have three GPS receivers with aerials in the panel at the back of the chart table, alone, so no... but the point being made is surely about spoofing of GPS signals?
    Last edited by Kukri; 09-08-19 at 10:43.

  8. #8
    Join Date
    May 2003
    Location
    SPAIN,Galicia
    Posts
    12,720

    Default Re: Call yourself a navigator?'

    The naval characters I have seen in films read their position directly off the sextant.....

  9. #9
    Join Date
    Jul 2008
    Location
    East coast UK. Mostly. Sometimes the Philippines
    Posts
    9,812

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by Wansworth View Post
    The naval characters I have seen in films read their position directly off the sextant.....
    No; they have just memorised the tables and the Almanac and are good at mental arithmetic...

  10. #10
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,978

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by GHA View Post
    Anyone here actually lost all the gps's onboard and had to resort to astro on an ocean passage?
    Not on ocean crossing but in the Bay of Naples. Plotter lost signal, then tablet also. Within a few miles both came back. I was advised to contact a man who was investigating these black holes and was told this was a well known one. Military probably.
    Answers to some technical queries at new website http://coxeng.co.uk

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