Hydrex Broadens Its Horizons With New Bow Thruster Replacement Methods

Wednesday, October 09, 2002
According to Boud van Rompay, executive director of Hydrex, "This new development will change the face of underwater repair work, as it provides a fast, yet top quality means to carry out such major jobs as thruster replacement and repairs." Rompay is referring to the successful replacement of the removal, repair and subsequent replacement of the vessel's seven-ton bow thruster and propeller - all of which was performed within the loading and unloading schedule of a 5,477 teu container vessel — in the Port of Rotterdam. Relying on more than 30 years experience, Hydrex engineers developed the cofferdam principle and adapted to what is today known as the "mobdock" (mobile mini dry dock). In this particular situation, the design of the vessel was studied in advance, followed by a technical plan that was created to remove the thruster underwater. Problems addressed included the shape of the vessel surrounding the bow thruster. Being irregular, it had to be measured precisely in order to construct specially designed mobdocks — on both the port and starboard sides. The thruster tunnel had to be sealed completely in order to prevent any water entering while dismantling work was completed. In response, a double-mobdock system was designed and manufactured before work commenced. Due to the degree of difficulty related to this task, Hydrex, (under Germanischer Lloyd certification) developed a new way to calculate, design and construct mobdocks for this purpose. The new installation techniques require exact precision in order to ensure water tightness, safety of workers and project success. Because weather conditions at the time of installation were inclement, installation was a challenge. However, since the mobdocks were well-designed, and the seals remained watertight, a secure and dry environment was present to commence the work 26-33 ft. (8-10 m) beneath the surface. Following the first inspection, it was obvious that one of the propeller blades had been broken off. In response, the three remaining blades and blanks have to be secured over the positions where they had been. A support system for the block and tackle was then welded into place on the ship's hull and two large metal supports were cut away from the gearbox, at which time the thruster was lowered and secured so that it could be removed once the mobdocks were taken away. The mobdock removal process involved bringing it back to the surface with the propeller blades inside. The thruster itself was then taken out from underwater, raised to the dockside and taken to the factory. The vessel was able to sail on its next leg of the journey after loading with containers was complete. Repairs were performed on the thruster engine and propellers, and all was readied for the return of Hanjin Vienna to Rotterdam within the next couple of weeks. This time the procedure for fitting the mobdocks in place differed from the first time, as they were already lowered underwater prior to arrival of the vessel.
Maritime Reporter September 2014 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Ship Repair & Conversion

Maritime Reporter @ 75: The Daily Cartoon

Maritime Reporter & Engineering News was founded by John J. O'Malley (1905-1980) in 1939, and today ranks as the world's largest audited trade publication in the world serving the maritime industry,

Mitsubishi Super Skiving System

Mitsubishi Heavy Industries, Ltd. (MHI) has completed development of the "Mitsubishi Super Skiving System" for machining internal gears with high speed and outstanding precision.

Messer to Debut MetalMaster Xcel

Messer Cutting Systems said it has answered the call from manufacturers that have been demanding a faster, more accurate way of producing cut parts. Messer’s

 
 
Maritime Security Maritime Standards Offshore Oil Pipelines Pod Propulsion Port Authority Salvage Ship Simulators Shipbuilding / Vessel Construction Sonar
rss | archive | history | articles | privacy | terms and conditions | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.0995 sec (10 req/sec)