We took usual steps:sounding the depth, reversing and stopping engine,paying out anchor and 60 fathoms of chain cable in the depth of 12 fathoms.The operation above is（）.

Which of the following is not a factor which can interfere with the pulse of sound and cause a variation the depth reading?（）

A.salinity
B.temperature
C.the hydrostatic pressure
D.Vessel’s speed

点击查看答案&解析

Who can contact the Designed Person?（）

A.the designated person
B.the captain
C.all senior officer
D.all officers and crew

点击查看答案&解析