Catenary as applied to tow lines denotes the（）.

单项选择题Besides saving distance along the track line，another advantage of the Scharnow Turn over the Williamson Turn in a man overboard situation because（）.

A.it is faster
B.it can be used in both the immediate action and the delayed action situations
C.in fog，if the turn is started as soon as the man goes over，the vessel will be at the point where he went over when the turn is completed
D.it returns the vessel to the original track line on a reciprocal course

单项选择题At night，a vessel shall indicate that she is restricted in her ability to maneuver by showing in a vertical line two（）.

A.red lights
B.red lights and two white lights
C.red lights with a white light in between
D.white lights with a red light in between

单项选择题As a vessel falls off the wind from close-hauled to a beam reach，the tendency for the vessel to move sideways through the water will（）.

A.increase
B.decrease
C.change only if the vessel comes about on the opposite tack
D.not change

单项选择题As a ship moves through the water，it drags with it a body of water called the wake. The ratio of the wake speed to the ship’s speed is called（）.

A.propeller velocity
B.speed of advance
C.wake distribution
D.wake fraction

单项选择题Apparent wind speed blowing across a vessel under tow can be measured by a(n)（）.

A.barometer
B.wind vane
C.anemometer
D.thermometer