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Cancel Culture's latest: Compass Heading Errors:

Discussion in 'Technical Discussion' started by JWY, Aug 26, 2020.

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  1. NYCAP123

    NYCAP123 Senior Member

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    I learned it in Basic Boating class when I was 9. After that I just remembered the formula. That's why I'd forgotten all about it. Plus I rarely used it once I had GPS. If you're traveling a short distance you really don't need it. In fact you don't even need a compass card (which most boaters never get) for most cruising. Close is close enough. But if you're traveling long distance being off by even a degree or two could have you missing the island you're looking for. Just ask Amelia Earhart. Oh that's right, she was never found. Draw a course line from Vancouver to say Hawaii. Now change the course by a couple of degrees and see where you'll end up.
  2. Pascal

    Pascal Senior Member

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    because the true heading you will get from a paper chart is way off once you factor in deviation and all
  3. NYCAP123

    NYCAP123 Senior Member

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    If you're off course by 1 degree, for every mile you travel you'll go off course 92.2'. You'll find your port or inlet if you're traveling a few miles, but if you're going several hundred or a few thousand miles you'll probably have to learn a language you weren't expecting to.
  4. Pascal

    Pascal Senior Member

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    Just like when crossing the stream can result in a 20 degree drift. Then the guy coming the other way at slow speed also had a 20 deg drift ... good luck figuring out that the nav lights and why that green light keeps getting closer
  5. Ward

    Ward Senior Member

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    I know that and I know plenty of trig so I know how a small error adds up over a long distance...

    What I mean is, every Canadian Hydrographic Service has a compass rose showing both true and magnetic, so there's no need for a calculation, you plot where you want to go and then read off either true or magnetic depending on what you need.

    And a mnemonic for "adding westerly" deviations seems pointless because obviously you'd add or subtract as appropriate based on your own swinging of your compass.
  6. Ken Bracewell

    Ken Bracewell Senior Member

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    Ward- you're only getting half the equation with a chart. Next you need to know your compass deviation for your particular vessel on that particular heading. "Dull"= deviation
  7. mapism

    mapism Senior Member

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    But that's precisely my point: in this day and age, would anyone in his right mind rely on the compass for reaching Hawaii from Vancouver?
    Even assuming to do all the math very accurately, I only have two words for whoever would fancy giving it a try: good luck.
  8. Capt J

    Capt J Senior Member

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    Not hardly. I was running a new 65' MY and turned on the FB vhf after getting underway and lost everything. Turns out they wired the VHF backwards and it shorted out the entire backbone. It happens and with everything networked together, doesn't take a whole lot sometimes to crash the entire network.

    As for this, it's ridiculous. People need to just stop looking and finding ANY reason to be offended. How is someone offended by a monument of a person that has been there for over 100 years signifying something in history or Aunt Jemima on a box of pancake mix that she's been on for 100 years????? It's F'ing history. A person cannot be offended by objects, they can be offended by other people, but not objects.....it's ridiculous.
  9. Pascal

    Pascal Senior Member

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    Yeah but each person has at least a smart phone that will get you there. And an iPad...
  10. Oscarvan

    Oscarvan Senior Member

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    The mnemonic is obsolete, offensive and no longer consistent with majority cultural and social objectives. If you have any doubt ask a date rape victim, or your mother. As we evolve, for better or for worse, we adjust. What was acceptable 100 years ago is no longer. Of those resisting I ask whether they would be OK with their 14 year old daughter being the dull virgin? Are they still planning on marrying her off at that age? Has she been doing physical labor and deprived of education since she turned 8? That all used to be OK too you know. Cut the hypocrisy already.

    On the subject of navigation.... understanding dead reckoning, the compass and its quirks, no you don't need it anymore. Just make sure you have a way to power/charge all the gizmos. The odds of needing to fall back are slim. Does knowing it make you a better mariner, maybe. Knowledge is good. But knowing your limitations is better.
  11. ChiTown

    ChiTown Member

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    Tele -Vision Makes Dull Company

    Especially if you're watching CNN......**** I couldn't help myself....oh and I swore.....darn.
  12. Oscarvan

    Oscarvan Senior Member

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    Ironically.... in the aviation business a Course is a line on a map, and a Heading is something you turn to and steer. Tool me a while to get over that...... :D:D:D
  13. NYCAP123

    NYCAP123 Senior Member

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    It's the same thing on a boat.
    I'd bet there are probably a lot of boaters out there not having a clue what this is all about. Here's a good article to help your education:
    http://www.argonsailing.com/2016/02/true-virgins-diy-compass-deviation.html
  14. Oscarvan

    Oscarvan Senior Member

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    On a boat I steer a course..... In an airplane I fly a heading.
  15. NYCAP123

    NYCAP123 Senior Member

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    Exactly. You steer the course on your GPS or chart that you've chosen. Your heading is 090*, etc. Let's say you're crossing a shipping channel and a ship asks your intention. Your response would be something like 'I have you on an EBL. My heading is 120*, speed 12 kts and my course and speed should have me crossing 1/4 mile behind your stern'.
  16. sgawiser

    sgawiser New Member

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    You can argue whether the wording should be changed, but I would argue that you ought to at least know how to navigate without electronics. It happened to us twice when we had to navigate with a paper chart and a compass. We were just lucky that the compass was properly swung.
  17. NYCAP123

    NYCAP123 Senior Member

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    You mean chart plotters aren't infallible?:eek: Charts are cool. To lay one out is like exploring before you explore. There's so much information you get that doesn't register when looking at a screen. Plotters are great for getting you there and doing things fast. Each has their place. So I always taught people to have paper on board. They'll probably look at the charts about as often as they look at that coffee table book, but the charts will be a whole lot more useful when they do.
  18. NYCAP123

    NYCAP123 Senior Member

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    Btw, I doubt your compass is "properly swung". That's near impossible. Hence compass cards. It's more likely close enough to do the job in the distance you were traveling. My guess is you'd have missed your mark if you were heading to like Bermuda.
  19. Seasmaster

    Seasmaster Senior Member

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    Aw Hell. . . I can't resist throwing a little atomized gasoline [excuse me, "accelerant"] into this thoughtful and hyperbolic conversation.
    Y'know, back in the "old navy", it was something about true virgins at weddings [he didn't reference un-true virgins] - And CDR Richard Hobbs was a proponent in his third edition of "Marine Navigation". When I went into the merchant Marine, in the American Merchant Seaman's Manual, 6th ed. it was something about dead guys voting twice..

    Now with this cancel-culture permeating our existence, we can't use that because some members of the "donkey" party might be offended due to allegations of some deceased homo-sapiens voting by mail - more than once. . .

    And after reading some comments here, I'm wondering why the group, with the exception of Mr. Ken, was on to the clear & present danger of misogyny on full display? ? ? [JW & NORSEMAN BOTH KNOW I'm am being TOTALLY SARCASTIC! ! !

    We could explore other versions, but why deny the opportunity for creative memes? ? ? On the other hand, does anyone really care? ? ? It's a stupid memory aid. . . not policy. C'mon man. Lighten-up!!!! Next thing you know, we won't be able to talk about "pool boys" & Liberty University in the same sentence!! [at least with a straight-face]
    YachtForums likes this.
  20. Seasmaster

    Seasmaster Senior Member

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    But - in the DEEP SEA world, we keep it really simple - "I intend to pass astern of you!" We leave out the "fluff"!

    And on another note - Ones heading may not be the same as their course, due to environmental concerns. Having towed seismic sensors through my working life, the vessel's heading was perhaps 25degrees off of CMG [course made good]. This made "optical solutions" problematic for concerned traffic!! [you ain't looking like your going in the direction you be pointed!!LOL]
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