Final answer:
When a vessel turns to starboard, the compass card in a magnetic compass remains stationary as it realigns itself with Earth's magnetic field.
Step-by-step explanation:
As a vessel changes course to starboard, the compass card in a magnetic compass remains stationary. This is because the compass card is designed to float in liquid and maintain its orientation relative to the Earth's magnetic field. When you turn the vessel to starboard, the compass housing (or bowl) turns around the compass card
The card itself does not turn with the housing; instead, it realigns itself with the Earth's magnetic field, thus appearing to remain stationary relative to the vessel. This can be illustrated by comparison with how a compass behaves on a stationary surface: the needle, or card in this case, always points toward magnetic north, regardless of the surface's orientation.