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Teric Compass Issue

Discussion in 'Shearwater Research' started by Macan, Nov 20, 2018.

  1. Macan

    Macan Tech Instructor

    # of Dives: 5,000 - ∞
    Location: Anilao PH & New York USA
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    Prior upgrading the Teric's firmware to V09, the Teric's compass is accurate, right off the box. Even when traveling to another location, there is no need to calibrate, the Teric's compass matches the reading of a mechanical compass. I've observed this several times while traveling and was quite impressed.

    However, I noticed that after upgrading to V09 firmware, the Teric's compass is off by 10 to 15 degrees when taken to another location. I have a Petrel 2 and it stays calibrated. Did the firmware upgrade change anything in the Teric's compass?
     
  2. FlaParrotHead

    FlaParrotHead Nassau Grouper

    # of Dives: 1,000 - 2,499
    Location: Kralendijk
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    37
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    Interesting .... we haven’t noticed this yet. Any other Teric users seeing this or anything similar.?
     
  3. Dustinainsworth88

    Dustinainsworth88 Garibaldi

    # of Dives: 200 - 499
    Location: Groves
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    Yes, one of my costumers just came back from the Bahamas yesterday, he said his Teric was off by 30° compared to two analog compasses. Even after calibrating the compass
     
  4. Saniflush

    Saniflush ScubaBoard Supporter ScubaBoard Supporter

    866
    764
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    Bermuda Triangle?
     
  5. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    7,978
    5,686
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    There seems to be an assumption in this thread that a mechanical compass is accurate. Not necessarily. They are manufactured with little magnets in them to calibrate them at that time; they are calibrated to a specific location. Those to be sold in Europe get that calibration; those for the US get a different one. There is no way to recalibrate them if you are a traveling diver. You need to check in each new location what its offset is, and incorporate that in your navigation.
     
  6. MaxE

    MaxE DIR Practitioner

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    I don’t follow this at all please explain further.

    On an analog compass the magnets point to magnetic north. The needle is magnetic or not, they are not and cannot be calibrated for a particular region. The variation between magnetic north and true north is declination, this does vary from location to location and an analog compass needs to be adjusted to account for this, but the needle is always pointing to magnetic north. A digital compass may or may not account for this and need to be re calibrated. Now magnetic north does move and in-fact has and will again flip from one poll to the next,
    but let’s not worry about that for the moment.
     
  7. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    7,978
    5,686
    113
    Sorry for the confusion. You are talking about declination; I am talking about inclination.
    For example:
    Suunto Compass Balancing
    The vertical intensity and direction of the earth's magnetic field, the inclination, influences the horizontal plane of a compass needle according to the latitude where it is used. Due to inclination, compasses must be balanced for different geographical zones in order to keep the needle in a horizontal position.

    Previously, the globe was divided into five different balance zones in which specific compasses functioned. However, as people travel more and more, the need for a compass with a greater geographical range has increased. Thanks to Suunto's 'Two Zone System' there are only two balance zones to consider in compass use — the Northern Hemisphere and the Southern Hemisphere. In practice, this means that a Suunto compass designed for the northern hemisphere will still work for a fair distance into the southern hemisphere, and vice-versa.
    And: http://www.mapworld.co.nz/global.html

    Short story:
    I was teaching the PADI navigation class once upon a time; it ahs three dives: (1) the one everybody is familiar with, from AOW, namely swimming a square; (2) swimming a presignated course with multiple non-right-angle turns and varying distances between the turns; and (3) swimming a "treasure hunt" with pre-laid hidden markers, each giving the distance and bearing to the next marker; you start by telling the student the distance and bearing to the first marker. Dives 1 and 2 went fine, exceedingly well, in fact. the 3rd was awful; the student started out 10-15 deg off from the intended bearing, so couldn't find the first marker. This happened twice, with some discussion and verification of compass-holding technique in between the two tries. Then we took his compass and laid it out on the wooden dock along with half a dozen others compasses borrowed from the observers. All pointed the same direction, except his, which was 10-15 deg off. We loaned him someone else's compass, and he swam the course without issues. Afterwards, he said he'd bought that compass on a trip to Australia. Dives 1 and 2 -- and most UW navigation -- is all relative....you take a sighting on a buoy and then swim to it underwater, for example. the compass could be way off, and that technique would still work. But not all navigation is like that.

     
  8. Av8tor22

    Av8tor22 Angel Fish

    # of Dives: 25 - 49
    Location: Kansas
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    My Teric has been having similar behaviors showing about 30 off course including on dives done from the same dive site before and after software update following an identical line.
     
  9. wKkaY

    wKkaY DIR Practitioner

    # of Dives: 500 - 999
    Location: Malaysia
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    Just adding to this thread. I find that I need to recalibrate my Teric's compass at the beginning of every trip even though they're roughly in the same area (different islands around Malaysia, dive trips about a month apart).

    Before recalibration, the compass behaves erratically, similar to what happens when you use a compass that's on its "edge" where the needle flip-flops 180 degrees.
     
  10. Rollin

    Rollin Professional Photographer

    # of Dives: 500 - 999
    Location: Belgium
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    52
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    Same here, in the three years before it was stolen, the compass of my petrel was very stable. The teric needs to be calibrated more often, sometimes twice a week. And for errors of 30-45°.

    I use a mechanical compass to check, but you can use a map as well when the error is that large. Not a big deal, but the reason why I still have to take a backup compass with me.
     

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