Terrestrial and Ship's magnetism :Components P, Q and R;

Of course. This is a fundamental topic in marine navigation concerning the magnetic compass. Let’s break down Terrestrial and Ship’s Magnetism, focusing on the key components P, Q, and R.

1. Terrestrial Magnetism (The Earth’s Field)

First, we need to understand the magnetic field the ship is sailing in. The Earth acts like a giant, weak magnet.

• Magnetic Poles: The Earth has a North and South Magnetic Pole, which are different from the geographic poles.
• Lines of Force: These invisible lines run from the South Magnetic Pole to the North Magnetic Pole.
• Components: At any point on Earth, this magnetic force can be broken down into two key parts:
  • Horizontal Component (H): This is the part of the Earth’s field that acts parallel to the Earth’s surface. This is the directive force that points the compass needle to Magnetic North. Its strength varies with latitude, being strongest at the magnetic equator and zero at the magnetic poles.
  • Vertical Component (Z): This is the part of the field that acts vertically, pulling the needle downwards. The angle it makes with the horizontal is called the Angle of Dip. It is zero at the magnetic equator and 90° (straight down or up) at the magnetic poles.