Magnetic variation and deviation

Question 1

what is magnetic variation

Answer 1

the difference in bearing caused by the difference between true north and magnetic north

Question 2

what is the magnetic deviation

Answer 2

the difference between true north and north on a compass due to ferrous metal objects on the vessel

Question 3

if the magnetic variation is west, do you add or subtract from the true bearing

Answer 3

Added

Question 4

if the magnetic variation is east, do you add or subtract from the true bearing

Answer 4

Subtract

Question 5

when a course is measured on a chart, what kind of course is it

Answer 5

True

Question 6

When a course is measured from a compass at the bow of the boat what kind of course is it

Answer 6

Magnetic

Question 7

When a bearing is measured from the cockpit what kind of bearing is it

Answer 7

compass

Question 8

what is taken into account converting a bearing from true to magnetic

Answer 8

Magnetic variation

Question 9

what is taken into account converting a bearing from magnetic to compass

Answer 9

Magnetic deviation

Question 10

what is taken into account converting from a true bearing to a compass bearing

Answer 10

magnetic variation and magnetic deviation

Question 11

what is magnetic variation caused by

Answer 11

magnetic north being in a different location than true north

Question 12

what must be checked when working with magnetic variation

Answer 12

that you are using the correct variation for the area you are sailing in

Question 13

where can variation information for an area be found

Answer 13

on the compass rose on the chart in question

Question 14

when is the one time that variation is 0

Answer 14

when true north, magnetic north and the vessel all are on one great circle.

Question 15

what small things can affect variation

Answer 15

geologic features such as deposits of iron or industrial equipment

Question 16

what is the number in brackets with a variation reading on an admiralty compass rose

Answer 16

the yearly change in variation

Question 17

how is yearly variation change measured

Answer 17

in minutes, or 1/60th of a degree

Question 18

how would you work out the current variation

Answer 18

take the variation and yearly change of the charts. check the chart publication date, then multiply the yearly change by years from publication, to get the change in magnetic variation since the chart was published. this can then be added to the charts magnetic variation to get the most up to date variation