Compass
Created | Updated Jul 20, 2003
A compass is one of the methods to orientate yourself.
A mechanical compass consists of a free rotating magnetic needle.
Electronic compasses are far more complex and make use of special electronic components called Hall effect sensors.
The earth has a magnetic field. You can imagine this as one very big and long bar shaped magnet through the whole planet. At two places this bar reaches the surface. These are the places where the magnetism is the strongest and called magnetic north pole and magnetic south pole. By design errors these poles are just not on the rotational axis of the earth.
Magnets attract each other in a polar fashion. Iron is attracted to a magnet in any orientation, while magnets brought together with the same pole will repel.
By using a free rotating magnetised needle one end will be attracted to the magnetic north pole and the other to the south pole. This makes the needle pointing north-south.
Just this line does not tell you very much. By giving the circle a scale in values the compass start getting usefull. The normal scale is called the rhumbcard and devides the circle in north, east, south and west and mostly a value in degrees.
A compass on board a vessel will have a fixed visor and by attaching the scale to the needle the visor will run over your course.
A handheld compass will have a hand rotatable scale. Looking along the visor to your heading you adjust the scale to match the needle. The visor will now run over your course on the scale.
You can easyly make a mechanical compass by oiling a sewing needle. Let it float ( using two other needles to place it very gentle ) on top of a cup of water. Any needle has magnetic prorties enough to let it point.
A mechanical compass consists of a free rotating magnetic needle.
Electronic compasses are far more complex and make use of special electronic components called Hall effect sensors.
The earth has a magnetic field. You can imagine this as one very big and long bar shaped magnet through the whole planet. At two places this bar reaches the surface. These are the places where the magnetism is the strongest and called magnetic north pole and magnetic south pole. By design errors these poles are just not on the rotational axis of the earth.
Magnets attract each other in a polar fashion. Iron is attracted to a magnet in any orientation, while magnets brought together with the same pole will repel.
By using a free rotating magnetised needle one end will be attracted to the magnetic north pole and the other to the south pole. This makes the needle pointing north-south.
Just this line does not tell you very much. By giving the circle a scale in values the compass start getting usefull. The normal scale is called the rhumbcard and devides the circle in north, east, south and west and mostly a value in degrees.
A compass on board a vessel will have a fixed visor and by attaching the scale to the needle the visor will run over your course.
A handheld compass will have a hand rotatable scale. Looking along the visor to your heading you adjust the scale to match the needle. The visor will now run over your course on the scale.
You can easyly make a mechanical compass by oiling a sewing needle. Let it float ( using two other needles to place it very gentle ) on top of a cup of water. Any needle has magnetic prorties enough to let it point.
