Magnetic
North is East of Grid North. It's also telling us
the rate of change. That's right  magnetic north
is not always in the same place! It changes from
year to year. In this example, the map is telling
us that the angle is decreasing by approximatily
7.6 minutes per year. Let's see now,
there's 60 minutes in each degree, and it's 6
years later now than 1995, so we subtract (6
years X 7.6 minutes) or 46 minutes from 5 degrees
(300 minutes) and 11 minutes. That's 311  46 =
265 minutes or 4 degrees 25 minutes.
Now keep
two things in mind.
Thing 1:
If our map was published 25 years ago, we might
be a few degrees off if we blindly use the
information on the chart.
Thing 2:
We're not piloting the Exxon Valdiz here, we're
pointing our canoe at a portage! Let's not get
real picky about where magnetic north is! In
fact, I'm going to use 5 degrees for the rest of
this lesson.
