23 Grid Navigation

Question 1

Describe a Standard Grided Chart

Answer 1

• A Polar Stereographic chart with the grid aligned with the Prime Meridian

Question 2

What is Grid Convergence?

Answer 2

• Grid Convergence is the difference between True North and Grid North
• Grid Convergence is zero at the reference meridian

Question 3

How can you calculate Grid Convergence?

Answer 3

• Grid convergence value is equal to the change in longitude (degrees) between the datum meridian and the point
• Since Constant of the Cone = 1
• Direction: if true north is east of grid north than GC is east and vis-versa for west

Question 4

What is the phrase regarding Grid Convergence and East and West?

Answer 4

• Grid Convergence East, True Least

- Grid Convergence West, True Best

Question 5

What is the formula for Grivation?

Answer 5

Grivation = Grid Convergence + Variation

• East is +
• West is -

Question 6

What is a line of constant Grivation called?

Answer 6

Isogriv