The compass calculator enlargement of this device shows how the Course Conversion Calculator makes corrections of the magnetic compass quickly and accurately. Magnetic compass – a rather unique device - especially for boaters in as much as they rely heavily on the magnetic compass when going from point A to point B. The magnetic compass is constructed with a number of magnets attached to the under side of a round card which has on the top side of the card numbers printed from zero (0), going clockwise to 360 (which is the same a zero). These numbers are set up in increments usually of 30 up to 360 (or zero) with short vertical lines between them that represent the degrees around the earth. What is somewhat unique is the fact that the arrangement of the magnets attached to the underside of the card, cause the card, when assembled into the compass, to point and remain fixed to the magnetic field in the earth. Although the boat may turn to starboard or port, the card does not turn with the boat. It only gives the appearance of turning. But because the card sits on a precisely honed spindle and is set in a stabilizing fluid, causes the number zero to remain fixed to the magnetic field in the earth and not turn with the other parts of the compass. The outer shell, along with the other parts of the magnetic compass do turn with the boat. The phrase magnetic compass correction implies that the magnetic compass is less than perfect and needs corrections. This is totally not the case. The culprit is not the magnetic compass, but rather it is the fact that the magnetic field in the earth (the magnetic axis) is askew from the true north axis – perhaps 300 or so miles west of the true north pole and requires a mathematical adjustment of the compass reading. Since traveling from point A to point B is based on the true north pole, mathematical corrections are necessary. These mathematical corrections vary depending on where you are located around the world in relation to the magnetic axis. Therefore making these mathematical corrections of your magnetic compass as you travel along your DR track, although not difficult, does become rather time consuming and frustrating due mainly to the fact that when traveling easterly the corrections are the opposite from the corrections necessary when traveling westerly. Also the corrections must be made quickly and accurately. With the turn of only a few dials, the Course Conversion Calculator does all of this quickly and accurately. It gives you a clear understanding of the magnetic compass and the fact that we are actually making a correction in the angular difference between the magnetic north pole and the true north pole and not the magnetic compass.       Navigation Aid Home Page Click here for a Video Demonstration of the Calculator

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