Mariners: Be aware of the shifting magnetic north

Boaters and ship navigators, it’s time to brush up on your compass correction skills. Magnetic north is shifting faster.

Many who have studied for a Coast Guard navigation exam will remember the following compass correction rhyme: True Virgins Make Dull Companions, or True +/- Variation = Magnetic +/- Deviation = Compass. And the inverse: Can Dead Men Vote Twice, or Compass +/- Deviation = Magnetic +/- Variation = True.

Magnetic north is moving its position on Earth at approximately 40 miles per year, from its present location in Canada near the Arctic Ocean to Russia. This is resulting in a change of about one degree in compass direction every five years. Uncorrected error can throw off your position a few miles in closer distances and hundreds of miles off over long distances.

Despite maritime and aviation’s heavy reliance on GPS systems, experts recommend that anyone in an industry using a compass needs to be aware of the magnetic movement. Charts should be updated and magnetic compass error incorporated.

Magnetic shift has occurred throughout the planet’s history due to the ever-moving molten core which affects the magnetic field. The shift increased from nine miles per year in the early 1900s to over 35 miles per year at the turn of the century.

Magnetic north is not to be confused with geographic north, i.e. the North Pole.

Airports around the country have been changing the names of their runways to reflect the shift.

Source: Sun Sentinal