Question

Define: (i) True Bearing (ii) Gyro North.

Hint:

When converting a bearing taken from a gyro compass to plot on a map, the navigator must apply the formula: $$\text{True Bearing} = \text{Gyro Bearing} \pm \text{Gyro Error}$$

Answer 1

Step 1: Defining (i) True Bearing:
In navigation, a bearing is the direction of an object or destination observed from the ship.
• True Bearing is the horizontal angle measured in a clockwise direction starting from the True North line (the geographic meridian pointing directly to the Earth's North Pole) to the line of sight pointing toward the observed object.
• It is always expressed in three digits, ranging from $000^{\circ}$ to $359^{\circ}$ (e.g., a True Bearing of due East is $090^{\circ}$). True bearings are the standard used for plotting all lines on navigational sea charts.

Step 2: Defining (ii) Gyro North:

• Gyro North is the specific reference direction indicated by the North-seeking axis of a ship's Gyro Compass.
• While a perfect gyro compass will point exactly to True North, mechanical friction, ship speed, and latitude can cause a slight mechanical misalignment. The direction the instrument actually points is called Gyro North.
• The angular difference between Gyro North and True North is known as Gyro Error (which is labeled as 'High' or 'Low' depending on the deviation).