Underwater repairs
SGS divers recently removed a cruise ship tunnel thruster unit, allowing it to be
rebuilt off-site before reinstallation
SWIFTER REPAIRS OUTSIDE OF DOCK
Repair projects in this sector have seen underwater diver technician teams help to ensure vessels avoid expensive downtime in dock. Clive Woodbridge reports
M
iami-headquartered Subsea Global Solutions (SGS), which this year celebrates its 80th
anniversary in the underwater shiprepair and maintenance business, has recently delivered a number of notable projects in US waters. A recent example involved its East Coast team, which completed the underwater removal of a Kongsberg TT3000 tunnel thruster from a cruise ship in Port Everglades, Florida.
A custom-built thruster removal sled and tunnel blank flange were designed and manufactured to ensure the safe extraction and sealing of the tunnel. After initially attending to remove gratings and prepare the necessary rigging, SGS divers removed the support strut, installed the sled system and worked in coordination with the cruise company’s internal teams to prepare the top hat assembly. The thruster was then unbolted, lowered using the sled system, lifted ashore by crane and sealed with a leak-tested blank flange. The unit was subsequently rebuilt off-site for re-installation by SGS divers.
In another notable US project, SGS handled a significant repair job when a fully laden container vessel lost rudder control near Los Angeles. The SGS West Coast team removed the 110tonne rudder afloat, coordinated repairs ashore and reinstalled it.
San Diego job SGS was also recently engaged to perform an urgent azimuth thruster repair for a subsea cable vessel in San Diego. The vessel was fully loaded with cable and preparing to depart for a seabed installation
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project in Fiji when a slow leak was detected at the port azimuth thruster’s steering seal. The scope of work undertaken by SGS included: conducting an inspection to locate the precise source of the leak; designing a customised packing gland housing as an alternative to a full seal replacement; fabricating the housing; and installing the solution underwater with its own dive team.
Upon initial inspection, it was determined that the steering seal, rather than the shaft seal, was the source of the leak. Given the vessel’s pressing schedule, a traditional seal replacement was not feasible. Instead, SGS’ technical services team engineered a customised packing gland housing that could be bolted onto the existing steering seal housing, effectively sealing the leak without requiring extensive disassembly. The vessel was cleared for departure on time, ensuring it could proceed with its seabed installation project as scheduled.
Earlier this year, SGS responded when a 120m ro-ro vessel required an immediate thruster installation and rudder bushing repairs, delivering an in-water solution at the Port of Portland, Oregon. Originally scheduled for drydock, the repair was re-planned to accommodate the vessel’s tight operational schedule.
To facilitate dry repairs for the rudder bushing, SGS’ technical services team designed and fabricated a customised reusable cofferdam, one of the largest of its kind ever built, directly at the repair location. The cofferdam fully encapsulated the 45tonne
THE NAVAL ARCHITECT
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