I don't think it could be used at sea. It senses turns through its wheels. A turn made by the ship on which the device sits would not be registered by the wheels.

Muslims might appreciate this device since it could be used to show the Qiblah direction (effectively a mobile mihrab) as they travel about. The Chinese revere the south - the most auspicious house direction in feng shui is south-facing - so the device may have been used in a manner similar to that of the Muslims, long before Mohammed.