Question 4223 Deck General

The correct answer is D. Turning response by use of the rudder only is NOT greater than on a single-screw vessel. The reasoning is that on a twin-screw vessel, the thrust from the two propellers counteracts each other, reducing the turning moment provided by the rudder. This makes the turning response less than on a single-screw vessel, where the thrust from the single propeller adds to the turning moment of the rudder. The other options are correct statements about the behavior of a twin-screw vessel with a single rudder. A is correct because the ship will steer a fairly steady course with the rudder amidships. B is correct because the wake against the forward side of the rudder is the principal force that turns the ship. C is correct because if one screw is stopped, the ship will turn toward the side of the stopped screw.