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  1. #21
    Join Date
    Jul 2008
    Location
    East coast UK. Mostly. Sometimes the Philippines
    Posts
    9,786

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by zoidberg View Post

    I recall one John Goode, a sea school Principal of the 'old school', describing how he clambered down low into a dinghy while on passage up the Red Sea, to give himself a much closer, more accurate, horizon as the low-lying normal one at around 7-8 miles was obscured in dust and haze.
    .
    That’s in Lecky’s Wrinkles. I made a friend of a ferocious Scots Fleet Manager by saying I’d once done it. Better using the accommodation ladder as the dinghy bounces about.

  2. #22
    Join Date
    Nov 2016
    Posts
    2,620

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by GHA View Post
    Enough time to get the sextant out?
    Here's a rhetorical question for you.....

    Have you any idea how to use a sextant - and usefully plot the result - to give you a Horizontal Sextant Angle, a Vertical Sextant Angle, a Distance Off..... It's my understanding all Merchant Navy Cadets had to use the 'works sextant' to navigate in the Coastal Trade - headland to headland - doing just that, with the added benefit of a Dumb Compass for relative bearings.

    Antarctic Pilot's contact should be able to confirm, as no doubt can Minn, that these basic, fundamental skills had to be mastered ( mistressed? ) before beginning to peek at Heavenly Bodies.

    It's not difficult. Anyone who can rub two brain cells together should be able to do it - provided, that is, they can 'be bovvered'.....


    ( And you have me pondering your use of 'GHA' as a monniker. To me, that 3-letter algorithm translates as 'Greenwich Hour Angle'. Do I scent a trollery? )

  3. #23
    Join Date
    May 2007
    Location
    Cambridge, UK
    Posts
    6,162

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by zoidberg View Post
    Here's a rhetorical question for you.....

    Have you any idea how to use a sextant - and usefully plot the result - to give you a Horizontal Sextant Angle, a Vertical Sextant Angle, a Distance Off..... It's my understanding all Merchant Navy Cadets had to use the 'works sextant' to navigate in the Coastal Trade - headland to headland - doing just that, with the added benefit of a Dumb Compass for relative bearings.

    Antarctic Pilot's contact should be able to confirm, as no doubt can Minn, that these basic, fundamental skills had to be mastered ( mistressed? ) before beginning to peek at Heavenly Bodies.

    It's not difficult. Anyone who can rub two brain cells together should be able to do it - provided, that is, they can 'be bovvered'.....


    ( And you have me pondering your use of 'GHA' as a monniker. To me, that 3-letter algorithm translates as 'Greenwich Hour Angle'. Do I scent a trollery? )
    I can certainly do all the coastal navigation uses of a sextant; they are all pretty easy and in pre-GPS days were a very useful addition to the toolbox, being capable of greater precision than compass bearings. My favourite was distance off - after all, that's why charts carry the height of marks! I know the theory of celestial navigation, but have never had to use it in practice. However, my knowledge of spherical trigonometry is certainly adequate for the job, and the use of the sextant for coastal navigation means that I can handle a sextant.

  4. #24
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    19,651

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by Minn View Post
    I meant C. Plath, Hamburg, who made sextants. Weems and Plath are an American chart agent who sell Tamaya sextants.
    Ah. I see. Many thanks.
    "Seamen are always wanting to do things the proper way; and I like to do them my way."

  5. #25
    Join Date
    Jun 2013
    Location
    Hopefully somewhere warm
    Posts
    9,626

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by zoidberg View Post
    Here's a rhetorical question for you.....

    Have you any idea how to use a sextant - and usefully plot the result - to give you a Horizontal Sextant Angle, a Vertical Sextant Angle, a Distance Off..... It's my understanding all Merchant Navy Cadets had to use the 'works sextant' to navigate in the Coastal Trade - headland to headland - doing just that, with the added benefit of a Dumb Compass for relative bearings.
    Vague idea but for fun could probably work it out pretty quick. For coastal nav if it goes awry the hand bearing compass is a much better bet imho.

    Back to the OP, if losing GPS position is a real worry then, for the majority on here, forget dashing out to buy a sextant, get out and practice some blind nav pretending it's not just the gps that's gone, but the sun is behind the fog as well. Just how good can you get an EP? Then the fog lifts, how close can you get plotting a position with and hand bearing compass? Will be much more useful than a sextant fix with who knows how many miles accuracy.

    Sextants are lovely though.

  6. #26
    Join Date
    Nov 2016
    Posts
    2,620

    Default Re: Call yourself a navigator?'

    Peering at that YouTube vid ( above ) showing Cdr Stephens on the nav wing bridge of HM Queen Elizabeth, I recognised the Pelorus...





    ....as I have one exactly like that. Even the same paint-job. Well, minus the pedestal and gimbals, but mounted on a ply board for clamping onto my coachroof. Geek!

    Well, how else is one to check compass deviation on a daily basis.....? Double-geek!

  7. #27
    Join Date
    Jun 2013
    Location
    Hopefully somewhere warm
    Posts
    9,626

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by Sybarite View Post
    No but in the time of Decca I lost all signals navigating up the E Coast of Ireland in thick fog. I had to resort to navigating by depth.
    Good reason to go practice some blind nav once in a while

  8. #28
    Join Date
    Mar 2007
    Location
    Atlantic
    Posts
    21,309

    Default Re: Call yourself a navigator?'

    A good friend of mine had a total loss of ability to charge his batteries mid atlantic. Starter motor on engine died. Navigated to Horta on astro....he is good at it. An unusual problem right enough.

    The loss of GPS signal may be more of a problem in the future though........who knows. But some Navies are now ensuring that they dont get lost.

    Not had much use for a handbearing compass or blind nav out on the blue floppy stuff though!

  9. #29
    Join Date
    Jul 2006
    Posts
    4,815

    Default Re: Call yourself a navigator?'

    Yes: Fixed GPS plus a "waterproof" Garmin 45 portable succumbed to excess salt water sloshing about below. By the time I'd washed it and dried it out in pieces in the oven it worked again and confirmed I could still do astro.

    Have had all normally working GPSs fail to get signal though on several different occasions in the same area of the China Sea. Almost certainly PLA Navy jamming.

  10. #30
    Join Date
    Jun 2013
    Location
    Hopefully somewhere warm
    Posts
    9,626

    Default Re: Call yourself a navigator?'

    Quote Originally Posted by capnsensible View Post
    A good friend of mine had a total loss of ability to charge his batteries mid atlantic. Starter motor on engine died. Navigated to Horta on astro....he is good at it. An unusual problem right enough.
    Must be unusual these days with so many mobiles/tablets onboard - a few minutes turned on to get a fix once a day would get you a long way.

    Would be fun to do a long one just with astro though, but ais is too useful solo & running the radar 24/7 eats too much juice.

    Maybe not the greatest idea to cross oceans with just one source of charging....?

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