high productivity core drilling systems include a drill string , an inner core barrel assembly , an outer core barrel assembly , and a retrieval tool that connects the inner core barrel assembly to a wireline cable and hoist . the drill string comprises multiple variable geometry drill rods . the inner core barrel assembly comprises a non - dragging latching mechanism , such as a fluid - driven latching mechanism that contains a detect mechanism that retains the latches in either an engaged or a retracted position . the inner core barrel assembly also comprised high efficiency fluid porting .