11 Direct Indicating Compass

Question 1

What are the three requirement properties a direct reading compass must have and how are these achieved in the E-type compass?

Answer 1

• Horizontality: Pendulous suspension system
• Sensitivity: Additional circular magnets, precision bearing (iridium tipped pivot in a jewelled cup), Oil which reduces weight
• Aperiodicity (dead beat): Oil dampens movement

Question 2

When are acceleration and deceleration errors on an E-type compass greatest?

Answer 2

When accelerating/decelerating in an East or West direction

Question 3

When are turning errors on an E-type compass greatest?

Answer 3

When turning through North or South

Question 4

What is the numeric used to determine acceleration/deceleration errors on an E-type compass?

Answer 4

• N.A.N.D.S

North Hemisphere. Accelerated. North. Decelerated. South

Question 5

What is the numeric used to determine turning errors on an E-type compass?

Answer 5

• N.U.N.O.S

- North Hemisphere. Undershoot. North. Overshoot. South

Question 6

What is the equation for calculating the amount of turning error (degrees) an E-type compass will experience?

Answer 6

Error (degrees) = (Lat + Bank Angle) / 2