Underwater Mount Thrusters

By: Thrustmaster Of Texas  11-11-2011
Keywords: Thrusters, Drilling Operations, Dynamic Positioning

Original Installation

Underwater Mount Thrusters for Dynamic Positioning are installed after the vessel is launched. Because of the need to insure an accurate fit and seal integrity Thrustmaster also designs and manufactures the receptacles. The receptacles are mounted into the hull by the shipyard before launching.


FPSO’s and semi-submersibles hold position over a drill site for months, even years. Dynamic Positioning thrusters are in service 24/7 during drilling operations. Interrupting drilling and leaving the site in order to repair a unit would be a costly decision. The Underwater Mount Thruster can be removed and exchanged without taking the vessel out of service.

The cutaway to the left shows three main components of the underwater installation system. The receptacle with the outer cap (top), the inner cap (middle), and the thruster (bottom). The inner and outer caps are installed at the factory and shipped to the site. Once installed into the vessel the outer cap is removed to access the inner cap. The inner cap is then removed to reveal the hydraulic steering motors and attachement for the cardan drive shaft.

The videos below show two methods of installation.


Dockside (on the left) refers to a new construction project where the thrusters are set on the sea floor in 20-30 meters of water with all thrusters being installed at the same time.

Replacement (right) refers to replacing the thruster in the open ocean during drilling operations.

Keywords: Drilling Operations, Dynamic Positioning, Thrusters

Other products and services from Thrustmaster Of Texas



Thrustmaster's product lines include fixed pitch propeller hydraulic and mechanical thrusters with direct engine drive, electric drive or hydraulic drive, and underwater mountable thrusters for the largest marine applications. Thrustmaster propulsion units can also be fixed or azimuthing and close fitted to the hull such as with Z or L drive propulsion, or stem mounted and tiltable with lengths up 35 feet for the 2000hp hydraulic thrusters.


Azimuth Thrusters

Azimuth thrusters are available in Z-drive configuration with direct diesel engine drive or in L-drive configuration for electric or hydraulic drive from overhead. They are available from 75 to 10,750 HP to replace conventional propulsion and rudder steering systems to perform both the propulsion and steering functions.


Tunnel Thrusters, Tunnel Thruster

Tunnel thrusters are primarily used for docking, slow speed maneuvering, emergency steering and station keeping at zero or slow forward speed. Tunnel thrusters are installed transversely in the bow or the stern of a vessel.


Retractable Thrusters

The retractable electric or hydraulic L-Drives deliver 360 degrees of steering in extended position, or tunnel power in the retracted position. Thrustmaster retractable thrusters are thru-hull azimuthing thrusters using fixed pitch propellers at variable speed. They use nozzled propellers and are used for dynamic positioning or slow speed course tracking applications.


Propulsion Units

Many options are available, including hydraulic kick-up of the outdrive, hydraulic propeller depth adjustment, remote control panels, choice of engines, etc. Modular barges of the British Navy use Thrustmaster OD150N with remote hand controls, sound attenuation, and manual backup tilt pumps. They are available with diesel or electric hydraulic drives with power ratings from 35 hp to 2000 hp.


Fixed Podded Drives

The engine can be placed at any convenient location as long as hydraulic piping or hoses connects between the engine driven hydraulic pump and the pod motor ports are available. The hydrostatic transmission provides fully proportional propeller speed control in forward and reverse with the engine running at constant speed much like a generator.