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
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.