Marine Surveyors Lexicon

Azimuthing thrusters replace a conventional propulsion and rudder steering system to perform both the propulsion and steering functions.

• Vessel maneuverability is greatly improved
• Vessel can turn 360 degrees in its own length
• Vessel can crash stop from full speed by steering the thrusters 180°
• Vessel can dynamically position, station-keep or berth under adverse weather conditions
• Superior Maneuverability and Control

Azimuthing thrusters provide maximum thrust in any direction, independent of vessel speed, offering superior maneuverability, especially in crowded harbor conditions. Azimuth (vectored) thrust is essential for station-keeping, accurate course tracking and dynamic positioning. Increased Efficiency

Because a vessel equipped with steerable thrusters does not require rudders or associated steering gear, the thrusters may be located at the optimal astern position often resulting in a propulsion efficiency greater than conventional propulsion with much greater maneuverability. The absence of rudders eliminates steering-induced drag The propellers can be positioned further aft, allowing larger diameter propellers for improved propulsion efficiency.

Non-retractable, thru-hull mounted, mechanical azimuthing marine propulsion drives which provide 360 degree vectored thrust.

A horizontal power input shaft transmits engine power through the upper spiral bevel gear set to a vertical power transmission shaft. The vertical shaft is connected to the propeller shaft through the lower spiral bevel gear set in the foot of the unit. The foot can be rotated endlessly through 360 degrees to steer propeller thrust in any direction.

Types of vessels benefiting from steerable propulsion installations:

• Tractor and Stern-Drive Tugs
• Pipe and Cable-Laying Vessels
• Diving and ROV/AUV Support Vessels
• Offshore Supply Vessels (OSV)
• Anchor Handling Tug Supply (AHTS)
• Semi-Submersible Drilling Rigs and Drillships
• Shuttle Tankers
• Passenger & Vehicle Ferries
• Floating Production & Offloading (FPSO)
• Crane Barges and Heavy Lift Vessels
• Salvage Vessels
• Military Vessels and Platforms
• Any vessel requiring improved maneuvering, station-keeping or DP capability

The reverse tractor tugs are technically advanced towing vessels in which the conventional propeller and rudder is replaced by an integrated unit, known as a Z-drive, which performs both propulsion and steering, enabling the tug to push or pull in any direction. With a Z-drive, tug maneuverability is greatly improved allowing the tug to turn on its own axis, stop within its own length when running at full speed, and hold its position and maneuver into dock in adverse conditions