Recently Hydrex diver/technician teams mobilized to vessels in Belgium and Curaçao for underwater hull plating repairs. In Zeebrugge a crack needed to be closed off and prevented from spreading further. For the operation in Curaçao a cofferdam had to be designed and constructed by us and then secured on the flat bottom of a fast support vessel.
This would allow the local shipyard to perform extensive work on the shell plating of the vessel from the inside without putting the ship in the dry, as there was no space available in the yard. The difficulty lay in the fact that the support vessel was made of aluminum, which prevents wet welding work. Hydrex R&D department therefore design a cofferdam that could be secured to the hull by other means.
The shipyard and the owner gladly accepted the proposal as it offered a fast and easy solution. Immediately after the operation was confirmed, a team mobilized to Curaçao. In the meantime the needed technical information was sent to Hydrex local support base. They took care of the construction of the cofferdam so that it would be ready when Hydrex team arrived on-site.
The team set-up a workstation on a workboat next to the vessel and then started the installation of the cofferdam. After it was secured, the crew of the shipyard could start the onboard repair work on the hull plating.
The hull of the ship had been damaged in two locations and initially the plan was to move the cofferdam after the first area had been repaired. Because of the deformation of the bottom plating it was however decided to construct a second cofferdam and cover up both damaged areas at the same time. Hydrex teams are trained to effortlessly adapt themselves if the scope of work changes. Working together with Hydrex local support base for the material, they quickly made the additional cofferdam and secured it to the shell plating.
The shipyard could then carry out all needed repair work on the shell plating in ideal circumstances without having to put the vessel in the dry, much to the satisfaction of the owner who did not have to wait for a space to become available.
Emergency crack repair
Hydrex divers are also certified welders and they can take care of any wet or dry welding work required for an operation, as was the case during the hull repair in Zeebrugge.
A roro vessel had collided with a quay wall and the owner contacted us to perform an inspection of the damage as well as any needed repair. A team immediately mobilized from Hydrex headquarters in Antwerp.
The operation started with a detailed underwater inspection of the damage. This revealed a 780 mm long crack on the bulbous bow, two meters under the waterline. Crack arrests were drilled on each side of the crack to prevent it from spreading further. A 850 mm x 60 mm doubler plate was then positioned over the damage and secured with wet welds.
A leakage test confirmed that the operation had been successful and the repair was approved by the classification society. This allowed the owner to keep the roro vessel sailing until the next scheduled drydocking.
Conclusion
Hydrex have the know-how and experience needed to find the best solution for any problem you might encounter with your vessel. This can be a simple routine repair or a unique complex one, as illustrated by these case studies. Hydrex can easily adapt a repair to your schedule. If required Hydrex can split up an operation and perform it in parts on different locations. Hydrex goal is to keep you sailing with as little delay as possible.
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Source: Hydrex
