What does the term 'deflection' refer to in the context of deviation?

In the context of deviation, the term 'deflection' specifically refers to the deviation caused by the ship's own magnetic field. As ships have various forms of magnetic materials and equipment on board, these can distort the magnetic compass reading. The magnetic field created by the ship itself interacts with the Earth's magnetic field, leading to inaccuracies in the compass heading. This phenomenon is crucial for navigating accurately, as it highlights how onboard factors can create discrepancies between the true heading and the compass reading.

The other options relate to different navigational concepts that are important but do not specifically define 'deflection' as it pertains to deviation. For instance, the angle between two reference points or compensation for external influences are broader navigation considerations but do not address the specific context of deflection derived from the ship’s magnetic field. Similarly, changes in compass heading due to wind refer to external environmental factors rather than the internal magnetic characteristics of the vessel itself. Understanding this distinction is essential for effective maritime navigation and ensuring accurate course plotting.