Question 4164 Deck General

The correct answer is D) The propeller gives it a helical motion. The slipstream of a vessel is the high-velocity flow of water caused by the vessel's propeller(s). This slipstream has a helical, or spiral, motion due to the rotational force imparted by the propeller. This helical slipstream can have a significant effect on the vessel's steering, particularly at low speeds, as it interacts with the rudder. The other answer choices are incorrect - the slipstream does affect steering (not A), its velocity is higher than the wake (not B), and it can affect the rudder even when the helm is amidships (not C).