Where must the draft marks be placed on a small passenger vessel? （）

A.shape of the vessel's underwater hull remains the same
B.vessel's center of gravity shifts to the center of the vessel's underwater hull
C.vessel's center of buoyancy shifts to the center of the vessel's underwater hull
D.vessel's mean draft increases

A.Subtract the draft of the vessel
B.Add the draft of the vessel
C.Subtract the sea water correction 
D.Add the sea water correction

A.There is a steady spotting area under the dockside block
B.Loading can be accomplished from a narrow apron without endangering the inboard boom
C.The system can be used for working the second deck of a warehouse
D.There is more accurate control of cargo drafts required to be stowed in the wings