An Azimuthing Stern Drive (ASD) tug or towboat is a high-performance vessel that is responsive, quick to maneuver and extremely powerful. In the hands of a skilled operator maneuvering these vessels looks effortless and seamless—smoothly spinning around, nimbly shifting position, having pinpoint control, all while the operator's hands move the control handles instinctively and naturally. This book takes the reader through an efficient learning sequence leading to that level of proficiency. Text, illustrations and practice drills create a clear understanding of ASD maneuvering principles and assist the reader in acquiring the intuitive hands-on feel required to operate these vessels. Each chapter covers a basic maneuvering element—steering, managing speed, stopping, hovering, lateral movement—and their application to light boat, barge and ship handling. This book is the first step for a professional mariner adding a new competency to his or her art of towing—driving a Z-drive.