Notices
Results 1 to 19 of 19

Thread: Can a car compass work?

  1. #1 Can a car compass work? 
    Forum Ph.D. Leszek Luchowski's Avatar
    Join Date
    Jun 2008
    Location
    Gliwice, Poland
    Posts
    807
    Hi folks;

    I bought one of those car compasses; a small globe of transparent plastic with a black ball floating inside, in some kind of fluid. The ball sports the markings you'd expect, N,E,S,W, and a big green arrow.

    This ingineous instrument immediately delivered two undeniably true pieces of information:

    1) My car is made of iron;
    2) A fool and his money are soon parted.

    That's quite a lot of knowledge for the equivalent of US$5.

    But now I want to get more knowledge for less, and I'd like some that is less trivial, so I came here with this question:

    - is there any way a compass could work in a car? I mean a magnetic compass, not gyro or GPS. And a "normal" car made of steel, not plastic, carbon fibe, or light alloys.

    Thanks in advance,
    Leszek.


    Reply With Quote  
     

  2.  
     

  3. #2  
    sak
    sak is offline
    Forum Junior sak's Avatar
    Join Date
    Sep 2007
    Location
    Presently at ME
    Posts
    210
    I donít know why a magnetic compass does not work in side a car? At leas I donít think so.
    According to me Dielectric strength is the property of material which gives resistance to electric flaw and magnetic field. For steel it is negligible. That means steel is a electric and magnetic conductor. It is not clear from your article what is the car made out of.
    Iím not well educated, so Iíld do some expiriments if you pass the compass to me.


    Reply With Quote  
     

  4. #3  
    Forum Ph.D. Leszek Luchowski's Avatar
    Join Date
    Jun 2008
    Location
    Gliwice, Poland
    Posts
    807
    Thank you, Sak, I will be very curious to hear about your experiences. You don't need my compass - try any compass you can get your hands on (other than GPS or a gyrocompass).

    Cars are usually made of steel (an alloy of iron and carbon, plus some other stuffs for better quality) - I mean the body at least, plus most of the transmission, plus parts of the engine, suspension etc. Steel is ferromagnetic, which is why you can try and make a magnet stick to the outside of a car. And to the inside if you find a place where the upholstery and trim isn't too thick over the metal. Large masses of ferromagnetic materials do interfere with compasses.

    Cheers, Leszek.

    BTW I think there are some types of steel which are not ferromagnetic, but I am not going to replace all the metal in my car just to make a compass work.
    Reply With Quote  
     

  5. #4  
    Administrator KALSTER's Avatar
    Join Date
    Sep 2007
    Location
    South Africa
    Posts
    8,231
    Could it be that your compass is a simple ornament instead of a real compass?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
    Reply With Quote  
     

  6. #5  
    Forum Ph.D. Leszek Luchowski's Avatar
    Join Date
    Jun 2008
    Location
    Gliwice, Poland
    Posts
    807
    Quote Originally Posted by KALSTER
    Could it be that your compass is a simple ornament instead of a real compass?
    It is very cheap and crude, but it does point to the (approximate) north when out of the car.

    I once strapped a reasonably good wrist compass onto the front light of my bicycle, hoping it would be there for me to see without having to turn my hand. It pointed towards the bike, instead of north. The bike was made of ordinary steel, not any of those newfangled chrome alloys.
    Reply With Quote  
     

  7. #6  
    Suspended
    Join Date
    Apr 2008
    Posts
    2,176
    Quote Originally Posted by Leszek Luchowski
    Thank you, Sak, I will be very curious to hear about your experiences. You don't need my compass - try any compass you can get your hands on (other than GPS or a gyrocompass).

    Cars are usually made of steel (an alloy of iron and carbon, plus some other stuffs for better quality) - I mean the body at least, plus most of the transmission, plus parts of the engine, suspension etc. Steel is ferromagnetic, which is why you can try and make a magnet stick to the outside of a car. And to the inside if you find a place where the upholstery and trim isn't too thick over the metal. Large masses of ferromagnetic materials do interfere with compasses.

    Cheers, Leszek.

    BTW I think there are some types of steel which are not ferromagnetic, but I am not going to replace all the metal in my car just to make a compass work.
    So are a lot of boats and they have compasses that work well.

    More expensive model compasses then the one that you are describing are used everyday on ships and planes. And there is steel in the ships and planes.

    They say there is a slight deviation. That you should check for and then calibrate into any long trip.

    http://terrax.org/geography/compass/compass.aspx

    I have only navigated a few miles off shore, using a compass. So I would not be worried about the slight deviation. And since I only know the course I am on, going out, I just reverse it coming back in. So it all means nothing to me.

    I have successfully brought a ship out and returned it within a couple hundred yards of the inlet I departed from, with winds and tides, using only a compass. I use simple wind and tide adjustments. A lot of abouts, about five degrees correction, about seven degrees correction, Ha-ha. Always good to pull into the inlet.

    I was out one day, years ago with my father, I was pretty young. We were blue fishing. Don't ever swim with the blue fishes. I would swim to a shark and kick him in the butt, before I swam to a bluefish school.

    The day was perfect and then rather suddenly there was a haze. So my father said pull up the umbrellas we are going in. I got one up right away and was on the second, when my father started a slow turn, back home. The umbrella was one that I manufactured and it was pretty heavy, it went down and snagged something.
    I am yelling to my father to slow down, because I am losing line. He said alright but it is getting rough out here. I had the umbrella about 50 yards from the boat, when I saw what I had snagged, it was a giant fluke or flounder or sole.

    I pulled him in and he was huge. My father said get the gear stowed because it is really getting bad. I just finished securing everything, and turned around to take a look back. And to my surprise the lights went out. I was looking at a black wall.

    As I am looking at the wall, my legs almost buckle underneath me. As if I was in an elevator that was on its way to the moon. I looked up to see what happened to the sky, and realized that there was a rolling wave, almost 90 feet high. My father did not like the way the wave was over taking the boat and pushing the stern around. A few of them passed us, and I got sea sick.

    My father gunned the boat, and for the next 30 minutes we were on a really cool roller coaster ride. The boat was capable when heading down into the waves of almost 50-60 miles an hour. It was a cabin boat that would do a maximum of 38 miles an hour on flat seas.

    Going up hill, or up wave, we could only go about 10-20 miles an hour.

    The captains chair was actually bending as we would hit the valley of the roller. Or a roller came from behind us and hoisted the boat up.

    When we got back, some laughed at me when I recounted the tale. My brother actually.

    Some years later my brother was out captaining a fishing boat, and he ran into this. The diesel engines went off the rpm scale when going into the valley of the wave. And he could barely keep the boat heading straight when going up the wave.

    In one valley before he started to reverse the engines into the valley. He blew the front windows out of the boat. After he cleared this phenomena, he went down to find passengers swimming after their tackle boxes and food.

    He acted very quickly and no one was hurt.

    But this phenomena can happen just offshore. Just thought I would share some high seas adventures with you.



    Sincerely,


    William McCormick
    Reply With Quote  
     

  8. #7  
    Forum Bachelors Degree
    Join Date
    May 2007
    Location
    NC USA
    Posts
    488
    *
    I too have one of those cheap compasses and I agree that it does not provide an accurate reading. I tried positioning it all around the cabin of the car and each time it gave a different reading.

    *
    Reply With Quote  
     

  9. #8  
    Forum Ph.D. Leszek Luchowski's Avatar
    Join Date
    Jun 2008
    Location
    Gliwice, Poland
    Posts
    807
    Quote Originally Posted by SteveF
    *
    I too have one of those cheap compasses and I agree that it does not provide an accurate reading. I tried positioning it all around the cabin of the car and each time it gave a different reading.
    *
    I am afraid the price (and quality) of the compass matters very little here. A (good or poor) compass will show (more or less accurately) the direction of the magnetic field in the place you put it. And if the iron of your car distorts, locally, the natural magnetic field of the Earth, a high-end nautical compass will very precisely tell you the direction of that distorted field.

    And you cannot adjust for the distortion by calibrating and remembering that, say, the true azimuth is 45deg. less than the compass says - because this difference will change every time you turn your car to a different direction. You would have to compile a look-up table by noting the true bearing for every possible reading of your compass. And the table would only be true while the compass is in one and the same place in the car. And it might be ambiguous - I mean you might get the same compass readings for two different real azimuths.

    I don't know how they make compasses work on metallic boats and ships. Perhaps there is some privileged point on a boat (a center of symmetry?) where the distortions caused by all the iron parts balance each other out? No idea.

    Is anybody around here familiar with tanks? I mean the combat vehicles, not liquid containers. Do they have magnetic compasses inside? I would be very surprised (unless they are built of Kevlar nowadays).

    Cheers,
    Leszek.
    Reply With Quote  
     

  10. #9  
    Suspended
    Join Date
    Apr 2008
    Posts
    2,176
    Quote Originally Posted by Leszek Luchowski
    Quote Originally Posted by SteveF
    *
    I too have one of those cheap compasses and I agree that it does not provide an accurate reading. I tried positioning it all around the cabin of the car and each time it gave a different reading.
    *
    I am afraid the price (and quality) of the compass matters very little here. A (good or poor) compass will show (more or less accurately) the direction of the magnetic field in the place you put it. And if the iron of your car distorts, locally, the natural magnetic field of the Earth, a high-end nautical compass will very precisely tell you the direction of that distorted field.

    And you cannot adjust for the distortion by calibrating and remembering that, say, the true azimuth is 45deg. less than the compass says - because this difference will change every time you turn your car to a different direction. You would have to compile a look-up table by noting the true bearing for every possible reading of your compass. And the table would only be true while the compass is in one and the same place in the car. And it might be ambiguous - I mean you might get the same compass readings for two different real azimuths.

    I don't know how they make compasses work on metallic boats and ships. Perhaps there is some privileged point on a boat (a center of symmetry?) where the distortions caused by all the iron parts balance each other out? No idea.

    Is anybody around here familiar with tanks? I mean the combat vehicles, not liquid containers. Do they have magnetic compasses inside? I would be very surprised (unless they are built of Kevlar nowadays).

    Cheers,
    Leszek.
    If I am not mistake because I did this test so many years ago over thirty. A compass will work inside a steel container. I believe that even some of the compass cases are steel.

    The magnetic field around the earth, is created by electricity. The effect is so large that it can polarize the entire object, so that steel will allow a compass to work just fine, even when the compass is totally surrounded by it. They say their is a slight deviation from true north and magnetic north though.

    I believe the steel around the compass levels out the effects of other steel objects around it.


    Try putting your compass in a coffee can. And then put it into a car.



    Sincerely,


    William McCormick
    Reply With Quote  
     

  11. #10  
    sak
    sak is offline
    Forum Junior sak's Avatar
    Join Date
    Sep 2007
    Location
    Presently at ME
    Posts
    210
    Compass need high level of steadiness or immovability or what ever you may call it. Otherwise the needle will touch the case and give error. This is all I can say.
    Reply With Quote  
     

  12. #11  
    New Member
    Join Date
    Aug 2012
    Posts
    1
    Has anyone considered that cars today use signals from the car's computer to sample and control various items in and around the vehicle. These E.M. signals will have an effect on the maginet in a compass.

    I bought the same black ball compass and I have been having a lot of fun with it. If I put the compass on the center console of my car and release the parking breaks the thing starts spinning like a top.


    I'm hoping to find that sweet spot where I can use the compass but I beginning to think that I'm stuck using the compass on my GPS.
    Reply With Quote  
     

  13. #12  
    Forum Isotope
    Join Date
    Feb 2012
    Location
    Western US
    Posts
    2,844
    Quote Originally Posted by Leszek Luchowski View Post
    Hi folks;

    I bought one of those car compasses; a small globe of transparent plastic with a black ball floating inside, in some kind of fluid. The ball sports the markings you'd expect, N,E,S,W, and a big green arrow.

    This ingineous instrument immediately delivered two undeniably true pieces of information:

    1) My car is made of iron;
    2) A fool and his money are soon parted.

    That's quite a lot of knowledge for the equivalent of US$5.

    But now I want to get more knowledge for less, and I'd like some that is less trivial, so I came here with this question:

    - is there any way a compass could work in a car? I mean a magnetic compass, not gyro or GPS. And a "normal" car made of steel, not plastic, carbon fibe, or light alloys.

    Thanks in advance,
    Leszek.
    I see that you've gotten a great variety of replies, spanning a wide range of accuracy and reliability.

    I've built and used magnetometers of various types and, as you've found, proximity to ferromagnetic materials poses a challenge. But all is not lost. That proximity by itself does not guarantee failure. The big challenge is that ferromagnetic materials get magnetized. The compass then sees a superposition of the earth's field (which you do want) and the car body's field (which you don't want). The solution is to demagnetize the car, so that the car body's field is kept negligible. In practice, it suffices to demagnetize the parts close to the compass (e.g., hood, rooftop, etc.), but YMMV. The old-style tape head demagnetizers will work, but better still are bulk tape erasers (the AC variety, not the unpowered permanent-magnet type).

    Performance of your compass will never be great, but demagnetizing the car body will improve performance to a useful point. I base that statement on personal experience. I had exactly the same problem with my $2 flea market compass. I spent more hours than I'd care to admit devising various solutions to the problem ("it's all for science," I tried to explain to my long-suffering wife). I made my own degausser, waved it over my car parts, and got things working well enough (of course, the more time I spent on it, the lower were my standards...).

    Important note: Make sure your credit cards and any other magnetized bits are kept well away from the degausser before you turn it on.

    Good luck!
    Reply With Quote  
     

  14. #13  
    Forum Senior TheObserver's Avatar
    Join Date
    Jan 2012
    Location
    Alberta, Canada
    Posts
    351
    Don't count on a response tk, this thread just had its fourth birthday lol
    Reply With Quote  
     

  15. #14  
    Forum Professor pyoko's Avatar
    Join Date
    Jun 2011
    Location
    Australia
    Posts
    1,094
    It could be that there is a UFO near your car when you try to operate the car compass. UFO's always cause compasses to behave strangely. When you step out of the cat, the UFO flies away. That is why it works outside. Hope this helps!
    It is by will alone I set my mind in motion.
    Reply With Quote  
     

  16. #15  
    Forum Ph.D.
    Join Date
    Jul 2011
    Posts
    984
    My car compass works fine.
    Reply With Quote  
     

  17. #16  
    Forum Freshman
    Join Date
    Apr 2012
    Posts
    13
    The real trick, as used on ships is to compensate the compass. Not practical in a car. In a ship it is accoplished by contantly changing directions and placing magnets around the compass to coax it to the best directions. In the end it is never perfect but the error is known and is compensated for. Thank tech for gyros and GPS.
    Reply With Quote  
     

  18. #17 car iron 
    Forum Freshman
    Join Date
    Dec 2012
    Location
    Surrey
    Posts
    14
    Yes why not compass is a natural element and it works in the car too, but the iron of car can disturb it.
    Reply With Quote  
     

  19. #18  
    Forum Freshman efbjr's Avatar
    Join Date
    Sep 2012
    Posts
    60
    Quote Originally Posted by Leszek Luchowski View Post
    Quote Originally Posted by SteveF
    *
    I too have one of those cheap compasses and I agree that it does not provide an accurate reading. I tried positioning it all around the cabin of the car and each time it gave a different reading.
    *
    I am afraid the price (and quality) of the compass matters very little here. A (good or poor) compass will show (more or less accurately) the direction of the magnetic field in the place you put it. And if the iron of your car distorts, locally, the natural magnetic field of the Earth, a high-end nautical compass will very precisely tell you the direction of that distorted field.

    And you cannot adjust for the distortion by calibrating and remembering that, say, the true azimuth is 45deg. less than the compass says - because this difference will change every time you turn your car to a different direction. You would have to compile a look-up table by noting the true bearing for every possible reading of your compass. And the table would only be true while the compass is in one and the same place in the car. And it might be ambiguous - I mean you might get the same compass readings for two different real azimuths.

    I don't know how they make compasses work on metallic boats and ships. Perhaps there is some privileged point on a boat (a center of symmetry?) where the distortions caused by all the iron parts balance each other out? No idea.

    Is anybody around here familiar with tanks? I mean the combat vehicles, not liquid containers. Do they have magnetic compasses inside? I would be very surprised (unless they are built of Kevlar nowadays).

    Cheers,
    Leszek.
    I had an automobile compass given to me years ago. I think it was bought at a yard sale. I mounted the compass in the center of the windshield directly behind the rear view mirror. It had an adjustment screw that allowed you to align it to Magnetic North, or True North, (Remember, the two directions are not the same, except in a few areas of the world.) I pointed the car to True North, (I had previously determined the proper direction.), and adjusted the compass. The compass gave me an accurate direction from there on.

    On a ship, the compass is mounted in a FIXED location. This assumes that the magnetic fields caused by the metal of the ship will remain constant. It is then aligned by either an adjustment screw, or by placing small blocks of metal near the compass which causes the alignment.

    More information can be found here:

    Compass - Wikipedia, the free encyclopedia
    "Quando Omni Flunkus Moritati"
    Reply With Quote  
     

  20. #19  
    Forum Freshman
    Join Date
    Jan 2012
    Posts
    66
    I got one of those. I took about 3 refrigerator magnets and positioned them around the compass until it zeroed in on the right reading as compared to another compass well away from the vicinity of the car. Not exactly accurate, but within reason for something cheap.
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •