Question 1146Navigation General

The correct answer is B) Visibility. Visibility cannot be accurately measured while on board a moving vessel because the motion of the vessel can distort and interfere with the measurement. The observer's view of the horizon and distant objects may be obscured or distorted by the vessel's movement, making it difficult to accurately assess the visibility conditions. In contrast, elements like wind direction, atmospheric pressure, and temperature can be more reliably measured from a moving vessel using appropriate instruments. The other answer choices (A, C, and D) represent weather elements that can be measured with reasonable accuracy from a moving vessel, provided the appropriate equipment and techniques are used.