FEATURE UNDERWATER REPAIRS
A T-foil being lifted prior to underwater installation by Hydrex
without drydocking. The company engineered and installed a custom-built 51m cofferdam, covering an area of 175m2
With the water pumped out, the company's dive team entered the cofferdam, gaining access to the damaged hull while the vessel remained afloat. Over 140m2
of steel had to be renewed, which was
made possible by the precise fit and structural integrity of the in-house engineered cofferdam.
In an important strategic development for the company, Wärtsilä Underwater Services has in recent months entered into a partnership with Megatugs of Greece. The new venture aims to combine Wärtsilä’s knowledge of shaft line and propulsion systems with Megatugs’ expertise in underwater services and salvage operations, to offer a more comprehensive and proactive approach to vessel maintenance. The benefits of the alliance, Wärtsilä says, will be to reduce vessel downtime; implement greener, regulation- compliant solutions; and offer more advanced underwater diagnostics and repair services on a global basis.
T-foils and cracks Meanwhile, Belgian underwater repair specialist Hydrex recently carried out the installation of a T-foil on a high-speed craft ferry during the vessel’s stay in Fort Lauderdale, Florida. The project was performed underwater, allowing the vessel to continue its operations without the need for drydocking.
46 , which was entirely designed in-house.
Before the installation could start, the external protection plugs on the hull were carefully removed to provide a clear surface for the new equipment. Hydrex divers/technicians then installed the threaded bars required to fasten the T-foil. This phase involved precise underwater work, as the correct alignment of the threaded bars was essential for maintaining the stability of the installed unit.
Once the preparatory tasks were completed, the T-foil was lifted into place and secured using tack welding. Following the installation, the Hydrex team conducted a thorough inspection to confirm that the T-foil was properly secured and aligned.
Hydrex has also recently undertaken a major crack repair to a car carrier during the vessel’s stay in Durban, South Africa. The crack was found to be 650mm in length, covering the weld seam of the starboard side rudder cover plate. To prevent the crack from spreading, crack arrests were drilled at its extremities. Next, the divers/technicians ground out the crack in a v-shape over its entire length as well as the surrounding area. Subsequently, a root pass was made in the crack, which was then filled with full penetration welding.
As a result of this repair, the vessel did not have to make an emergency visit to drydock, but could instead make arrangements for a follow-up repair at a more convenient time and location. ■
THE NAVAL ARCHITECT
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