The correct answer is D) There is no change. When a vessel enters shallow water, the rate of turn of the vessel does not change, assuming all other factors (propeller revolutions, rudder angle, etc.) remain constant. The rate of turn is primarily determined by the vessel's speed, rudder angle, and the vessel's hydrodynamic characteristics, which are not significantly affected by the depth of the water, as long as the vessel remains in deep enough water to avoid grounding. The other options are incorrect because a vessel's rate of turn is not faster (A) or slower (C) when entering shallow water, and the rate of turn does not remain constant for varying propeller revolutions (B), as the rate of turn is influenced by the vessel's speed and rudder angle, not just the propeller revolutions.