Question 1009Navigation General

The correct answer is C) speed over the ground. A Doppler log in the bottom return mode measures the vessel's speed over the ground, which is the speed of the vessel relative to the stationary seafloor. This is different from the speed through the water, which would be affected by the velocity of any current. The Doppler log determines the speed over the ground by measuring the Doppler shift in the reflected signal from the seafloor. The other options are incorrect because a Doppler log does not directly indicate the bottom characteristics (A), the depth of the water (B), or the velocity of the current (D). Those parameters would require different types of instruments or calculations.