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Underwater Blankings & Cofferdams

Whether your vessel is an offshore marine asset or transiting globally, we can provide custom hull blanking/cofferdam solutions that will allow repairs to happen in-situ as if they were in a dry environment, keeping your vessel on its planned itinerary and/or production schedule.

Subsea Global Solutions (SGS) has 30 years of experience in designing and building hull blanks, cofferdams, and hyperbaric habitats. All SGS locations around the world maintain various types of closed and open cofferdams for fasts response to any hull repair. Renewing wasted/damaged shell plate or spool pipes afloat eliminates the need for a dry dock.

The use of cofferdams to replace damaged shell plate or spool pipes is not new in shipping—however, what SGS has focused on for the past 10 years is developing and qualifying in-house welding procedures for both dry and wet applications using class A underwater wet welding procedures in combination with topside procedures. This unique approach has enabled SGS to provide turn key repair solutions for doing permanent—no condition repairs afloat. The gouging and welding of root one sided welds can now be done underwater after the dry repair is completed with the underwater wet welds meeting class approval, as per the Class A requirements of AWS D3.6M: Underwater Welding Code.

In-house built drawings can be provided for thermal heat barrier type blanks and tailored cofferdams with complex shapes/contours that SGS can typically design on the job site. With built drawings, class approval can be obtained for any cofferdam at the customer’s request, as we have the equipment and design expertise to allow any repair types to be executed without fit up concern.

In some cases, SGS installs hull blanks that are designed to remain on the hull while the vessel is in transit undergoing repairs. We have various options for enclosed cofferdams, open-top cofferdams with man entry, and open-bottom cofferdams (or hyperbaric cofferdams) for repairs that are required beneath the surface. If we do not have one shaped and sized for your unique requirements, we will design one to ensure a proper fit with safe execution.

Whether your vessel is an offshore marine asset or transiting globally, SGS can provide custom hull blanking/cofferdam solutions that will allow repairs to happen in-situ, keeping your vessel on its planned itinerary without expensive deviations to a dry dock while minimizing off hire time.

Common Use Cases for Blankings/Cofferdams

For underwater repairs or underwater exchanges on tunnel thrusters, tunnel thruster seals, tunnel thruster blades, stabilizers fins, propellers, propeller blades, stern seals, rudders, and rudder seals—please see our unique underwater ship repair options here.  

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Looking for Underwater Maintenance & Repair Services?

SGS has an unparalleled technical capability to deliver turn-key solutions at a global scale.
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Case Studies

Hull Breach on Tanker

During cargo operations, a submerged pile pierced through the hull. SGS worked together with owner and class to develop repair plan that included the design and installation of an engineered cofferdam.

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Offshore Oil & Gas

A Blue-Chip oil & gas company incurred several defects and cracks in a critical attachment member of an FPSO’s hull – these defects required repair to allow continued operation.

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Skeg Ripped from Azipod

3 month out of dry dock, galvanic corrosion caused heavy cavitation/erosion damage on PORT and STBD side rudders.

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SGS Reseats Shifted Tailshaft Afloat and Executes a Stern Seal Repair

The client indicated that the tailshaft had shifted aft approximately 200 mm when the ship’s crew was doing maintenance on the shaft coupling. It resulted in the aft water seal losing contact with the liner, causing large amounts of water ingress into the stern tube.

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SGS Completes an Afloat Rudder Stock Seal Replacement

This complex underwater repair was completed to the client's satisfaction in 5 days in conjunction with various other repair works. SGS managed both the underwater and internal portions of this repair to ensure each phase was executed seamlessly.

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Underwater Propeller Blade Straightening – Cold Static Loading

SGS can restore your propeller blades as a permanent repair, to OEM design geometry by cold static loading with our underwater propeller blade press.

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Double Bow Thruster Removal by SGS

The benefits of removing a damaged bow thruster afloat are many. The customer was able to prevent further damage to the bearings and gears caused by the presence of seawater in the gear housing and the procedures allows the units to be overhauled prior to the vessels next dry-dock—or, they can be re-installed afloat by SGS, which would help to eliminate the need for additional tug cost.

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Afloat Bow Thruster Blade Seal Exchange by SGS

The project was executed with two SGS teams working around the clock. While the vessel trimming process was in motion, the team onboard the vessel began to drain the oil from the thruster while the dive team began removing the bow thruster tunnel gratings to gain full access to the bow thruster.

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Scrubber Overboard Spool Pipe Repairs with 5 Year Warranty

The installation of complete SOx scrubber systems is entirely possible without taking the vessel out of the water. SGS’s involvement is focused on precision cutting of the hull penetrations for the sea chest openings and overboard spool pipe installation below the waterline.

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SGS solves serious problems: Assisting a large, fully laden post-Panamax container vessel with steering issues

SGS solves serious problems: Assisting a large fully laden Post-Panamax container vessel with steering issues. SGS works with port authorities, class, and manufacturers to provide class-approved in-water float out removal, repair, and refit of a 110 mt rudder. Find out how our underwater inspection and survey services deliver practical, cost-effective solutions to a complex offshore problem. SGS works with port authorities, class, and manufacturers to provide class-approved in-water rudder float out removal, repair, and refit of a 110 mt rudder. Helping owners safely reduce their risk exposure and related costs that would include diversions, delays, and downtime.

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Galvanic Corrosion on Rudders

3 months out of dry dock, galvanic corrosion caused heavy cavitation/ erosion damage on PORT and STBD side rudders.

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Underwater Blankings & Cofferdams

Hull Cleaning

Subsea Global Solutions (SGS) has 30 years of experience in designing and building hull blanks, cofferdams, and hyperbaric habitats. All SGS locations around the world maintain various types of closed and open cofferdams for fasts response to any hull repair. Renewing wasted/damaged shell plate or spool pipes afloat eliminates the need for a dry dock.

The use of cofferdams to replace damaged shell plate or spool pipes is not new in shipping—however, what SGS has focused on for the past 10 years is developing and qualifying in-house welding procedures for both dry and wet applications using class A underwater wet welding procedures in combination with topside procedures. This unique approach has enabled SGS to provide turn key repair solutions for doing permanent—no condition repairs afloat. The gouging and welding of root one sided welds can now be done underwater after the dry repair is completed with the underwater wet welds meeting class approval, as per the Class A requirements of AWS D3.6M: Underwater Welding Code.

In-house built drawings can be provided for thermal heat barrier type blanks and tailored cofferdams with complex shapes/contours that SGS can typically design on the job site. With built drawings, class approval can be obtained for any cofferdam at the customer’s request, as we have the equipment and design expertise to allow any repair types to be executed without fit up concern.

In some cases, SGS installs hull blanks that are designed to remain on the hull while the vessel is in transit undergoing repairs. We have various options for enclosed cofferdams, open-top cofferdams with man entry, and open-bottom cofferdams (or hyperbaric cofferdams) for repairs that are required beneath the surface. If we do not have one shaped and sized for your unique requirements, we will design one to ensure a proper fit with safe execution.

Whether your vessel is an offshore marine asset or transiting globally, SGS can provide custom hull blanking/cofferdam solutions that will allow repairs to happen in-situ, keeping your vessel on its planned itinerary without expensive deviations to a dry dock while minimizing off hire time.

Common Use Cases for Blankings/Cofferdams

For underwater repairs or underwater exchanges on tunnel thrusters, tunnel thruster seals, tunnel thruster blades, stabilizers fins, propellers, propeller blades, stern seals, rudders, and rudder seals—please see our unique underwater ship repair options here.  

CONTACT US NOW

Looking for underwater maintenance and repair services?

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