After an inspection performed by a Hydrex diving team revealed damage to the bearings of a thruster of a 300-metre container vessel, the company proposed a plan to remove the unit in-situ in Rotterdam so that it could be overhauled.
A diver-technician team working on the vessel disconnected the thruster's hydraulic piping and the engine room was closed off from the thruster tunnel with a temporary blank. Next, the grids closing off the thruster tunnel were removed to give the divers access to the unit. One by one the blades were detached and replaced by a blind flange to prevent oil leaking from the thruster.
The gearbox was then secured with hoisting equipment after which it was fully disconnected from the thruster room and lowered onto a cradle. This cradle was designed especially for thruster operations and can be adjusted to the size of the unit. It prevents the thruster from tipping over and allows Hydrex divers to remove the unit (or bring it back in) in one take.
The thruster was subsequently brought to shore, ready to be overhauled. A flange was positioned over the space connecting the thruster tunnel to the vessel, securely sealing off the room and allowing the vessel to sail until the overhauled unit will be reinstalled. The temporary blank in the engine room could then be removed, completing the operation.
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