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I have an Iphone 12 which has a compass app. I've tried it out against city streets that have a known directional angle and it seems to be accurate. But the paper map orientation course still wants you to bring a physical compass so I imagine there is a difference.

So assuming I have an advanced smartphone with a built-in compass, would I still want a traditional one as well? I am aware that the phone is less reliable but are there other reasons too, such as accuracy or ease of reading?

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    I find there is some irony in the fact that you are signing up for a paper map course but are trying to use a phone compass.
    – noah
    Jul 15, 2021 at 20:50
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    @JonathanReez: I could see a couple of downvotes to the question. IMO, it is because if tends to sound opinion-based, although it is not entirely that way. I am going to edit the tile in a way that stages it better. You can revert back if you disagree.
    – WedaPashi ♦
    Jul 17, 2021 at 7:57
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    @Gabriel: Deleting the first comment as if felt pretty direct for no apparent reason.
    – WedaPashi ♦
    Jul 17, 2021 at 7:59
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    This is a mind-boggling question. I am pleased to see @Gabriel answering it with grace. It staggers me that people would still try and find a way to not bring a $10, 1 oz piece of equipment that has served humans for hundreds of years and does not fail. Invert the question, what benefits could a cellphone compass possibly have over a physical one?
    – Venture2099
    Jul 19, 2021 at 9:33
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    A quick browse shows the OP posting several questions and comments trolling this kind of mentality. Imagine wanting to carry excess weight and power into the wilderness...
    – Venture2099
    Jul 19, 2021 at 9:46

1 Answer 1

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A phone app lacks many features that compasses have which are essential to orientation. Among the main ones:

  • A transparent casing that makes it possible to read the map through the compass and align the grid to the needle.
  • Numeric scales and rulers that enable you to make measurements on the paper map
  • (not on all models) Mirror with sight lines or reticles that enables you to sight landmarks and read the compass needle at the same time for more precise aiming
  • (not on all models) Mechanism to adjust dial for magnetic declination

Another quite important thing to know is that scattered around the world are magnetic anomalies, mostly ferromagnetic deposits. Considering electronic compasses drift pretty quickly and they need to be self-calibrated regularly, there is a chance that you could calibrate your electronic compass with a local bias, which would make it misaligned even when you left that area. This would not happen with a regular compass. The anomaly would skew the compass but it would return to normal afterwards.

Some anomalies are quite limited in range, but I've experienced a couple while sailing in the Caribbean that would disrupt the pedestal compass for at least a mile.

But more importantly, a phone will not work if the battery is dead. A compass will always work unless you accidentally demagnetize the needle.

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    Bear in mind, and I think I'll update my answer to reflect this, electronic compasses drift like crazy and they need to be self-calibrated regularly. Couple that with possible local magnetic anomalies, and you could skew the calibration significantly.
    – Gabriel
    Jul 16, 2021 at 0:29
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    Apps can probably automatically adjust for magnetic declination using the phone's GNSS position, but you need to learn and practice how to apply the declination manually. In my area the bias is almost 20°W so if your phone is dead and you have not practiced how to account for this using the analog method, you're going to get off-course really quickly.
    – Gabriel
    Jul 16, 2021 at 1:35
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    @Gabriel they might be able to use GNSS to address declination, but that either requires them to store declination data or download it on the fly. They may not have a signal, and I don't know if there's a suitable source of data anyway
    – Chris H
    Jul 16, 2021 at 11:28
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    Enabling True North won't make it more accurate, but will make it match the map better. Perhaps that's a subtle distinction, but when you learn about magnetic declination it will become an important one. With how rarely I use my phone compass for anything significant, I end up calibrating it every time.
    – Chris H
    Jul 16, 2021 at 11:35
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    And the compass can be left in a pocket of your pack, so you will always have it and it will always work.
    – Jon Custer
    Jul 18, 2021 at 15:12

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