A virtual rise in the center of gravity may be caused by（）.

单项选择题A vessel is equipped with twin propellers，both turning outboard with the engines half ahead. If there is no wind or current and the rudders are amidships，what will happen?（）.

A.The bow will swing to starboard
B.The bow will swing to port
C.The vessel will steer a zigzag course
D.The vessel will steer a fairly straight course

单项选择题A twin-screw vessel with a single rudder is making headway. The engines are full speed ahead. There is no wind or current. Which statement is FALSE?（）.

A.If one screw is stopped，the ship will turn toward the side of the stopped screw
B.The principal force which turns the ship is set up by the wake against the forward side of the rudder
C.Turning response by use of the rudder only is greater than on a single-screw vessel
D.With the rudder amidships，the ship will steer a fairly steady course

单项选择题A single-screw vessel going ahead tends to turn more rapidly to port because of propeller（）.

A.discharge current
B.suction current
C.sidewise force
D.thrust

单项选择题A record of the types and strengths of steels used on a ship must be included in the（）.

A.general plans
B.builder's documentation
C.Certificate of Inspection
D.construction portfolio

单项选择题A liner in riveted construction of a vessel is a(n)（）.

A.small plate which fills the aperture between riveted strakes and the vessel framing
B.backing plate which is used to level the strakes while riveting，and then removed
C.internal frame to which the side shell is riveted
D.seam that is welded after riveting is completed