Last month Hydrex sent a team to Maloy, Norway to carry out a cofferdam installation on an expedition ship.

According to a statement, the vessel had suffered a large crack as well as a smaller one in its shell plating and was not allowed to sail.

A fast, on-site, temporary repair was needed to allow the ship to sail to drydock, the company said and after the job had been confirmed, Hydrex immediately mobilized diver/technicians to the vessel’s location together with all the needed equipment.

Temporary repairs had been performed by another company on both cracks to stop the leaks, but these were unfortunately not strong enough. The classification society did not allow the ship to sail to drydock for permanent repairs.

The team removed the patch covering the large crack and performed an inspection of the damage. This revealed that the crack had a length of 2,000 mm and a width of 1,400 mm.

Based on the finding of this inspection Hydrex proposed the installation of a cofferdam covering the affected area. 

Because the crack was situated in the turn of the bilge, it was important that the cofferdam was constructed to the exact shape of the hull. 

The cofferdam, measuring 2,400 mm by 2,000 mm, was fabricated on-site by the certified diver/welders. It was then lowered into the water and positioned over the damage. Next the team secured it with screw dogs and additional fortifications. The cofferdam could then be emptied of water. 

The other crack was much smaller with a height of 100mm. The divers covered it with a double plate which was welded in position.

The area around the crack had also been deformed and the bilge keel had been severely bent. Fortunately, no immediate repairs to these damages where needed as they did not weaken the integrity of the hull, Hydrex said.

They would be handled in drydock together with a permanent repair of both cracks. The operation was approved by the classification society and the ship was allowed to sail to drydock.