Balanced Compasses Eliminate Dip

From Ocean Navigator #131
July/August 2003
Without batteries or power cords, magnetic compasses use the earth’s magnetic field to determine direction. However, the earth’s field is not perfect. First, there’s variation, the annoying waver in the field that requires the navigator to crunch a few numbers, different for wherever the boat happens to be on the globe. The same is true of deviation: Corrections are made for the heading of the boat. And then there’s the problem of the compass card dipping when it approaches the poles. For high-latitude sailing, a compass needs to be adjusted to accommodate the tendency to point downward.

For the past 20 years, product development crews at Danforth Compass in Gloucester, Mass., have been puzzling over how to balance a compass card to allow for the use of one compass – a standard, off-the-shelf model – anywhere in the world. The first balanced compasses are now available, thanks to a team of developers at Danforth.

“We have been thinking about this for a long time,” said Ken LeBlanc, Danforth’s product manager for compasses. “We finally figured it out – we decoupled the motion by installing a magnet in the inner float chamber.”

LeBlanc allows that he had some help. “We had some assistance from MIT engineers.” Danforth is calling its product Global Balance, a magnetic compass that can be used anywhere in the world.

By Ocean Navigator