In July Hydrex mobilized a team of diver/technicians to Syros, Greece, for a complex repair operation on a 118-meter, 8550 DWT chemical tanker. The vessel had suffered large cracks in her hull plating as the result of a collision. She was not allowed to sail any further. Hydrex proposed a permanent on-site repair using an open top cofferdam. This would enable the fully laden ship to continue her journey.
The tanker was berthed in Egypt when another vessel struck her portside hull. This caused a large hole, severe cracks and dented plating. The collision also pushed the vessel’s starboardside hard against the fenders, denting the plating on that side as well. The owner of the vessel contacted Hydrex to find the best repair solution for the vessel. Because it was fully laden, going into drydock was not feasible. An on-site underwater solution was needed.
In consultation with Hydrex, the ship’s owner opted to take his vessel to the Neorion Syros Shipyards, situated on the island of Syros in Greece. When the ship arrived, the classification society decided that the damage to the portside hull plating was too severe to let the tanker sail any further.
Neorion Syros Shipyards was established in 1861. It is the oldest yard in modern Greece and the largest remaining industry in the Aegean area. The shipyard constructed some of the first steel and steam boats in the 19th century. Starting in 1994 the yard underwent a technological evolution. An ambitious investment plan was implemented. One of the most important investments was the creation of infrastructure aimed at the construction of mega yachts or small cruise ships. The yard soon became famous for the quality of its services, provided by some of the most experienced craftsmen in the Mediterranean.
Getting the right measurements for the perfect solution
“After arriving on-site we first performed a detailed underwater inspection of the damage, ” the Hydrex team leader says. “We used the information we collected to come up with the best possible option for the repair. This was done in communication with the technical department at the Hydrex headquarters.” He then had a meeting with the superintendent of the vessel and representatives of the classification society and the yard to discuss the scope of work.
A permanent repair would be performed to the extensive damage to the portside plating. The less severe damage to the starboardside plating would be temporarily repaired. This would allow the tanker to sail to Hamburg, unload her cargo and then quickly drydock for a permanent repair to the starboardside plating.
The damaged area on the portside would be closed off with an open top cofferdam. This allowed the Hydrex team to create a dry environment in which the shipyard could perform permanent repairs in drydock-like conditions. “Using a special frame, exact measurements were made of the area that needed to be covered, ” the team leader explains. “With these measurements a custom cofferdam was designed by the Hydrex technical department. The cofferdam was then constructed by the shipyard.”
Creating the same conditions as in drydock, underwater
“The vessel was loaded with paraffin wax, ” says Mr. Andrew Anagnostis, Business Manager at Neorion Syros Shipyards. “So the cargo had to be kept in constant 70° C temperature to stay in a liquid state. In order to enable the yard to carry out the repair to the main damage in workable conditions, the crew of the vessel emptied the adjacent cargo tank.”
Once the open top cofferdam was ready, the Hydrex team installed it over the damaged hull plating in no more than two hours. All water was removed from inside the cofferdam. The yard then replaced the dented shell plating. The affected web frames were also replaced, using templates from the starboardside frames.
While the yard was performing the insert repair, the Hydrex diver/technicians installed temporary stiffeners over outside of the dented starboardside plating. “The reason they could not renew the damaged frames on this side was because the cargo could not be shifted, ” tells Mr. Anagnostis. “The temperature was around 70° on the bulkhead and about 45-50° in the other areas. So it was impossible for anybody to do any work, let alone weld.”
The repairs to both sides of the vessel were approved by the classification society. This allowed the vessel to sail from Syros. The tanker then made her way to Germany where she will be unloaded before paying a quick visit to drydock for permanent repairs to the starboardside hull plating. Because no further attention will be needed for the portside, the visit to drydock can be very short and economical.
The team leader told us that the cooperation with the shipyard went very efficiently. “Throughout the entire operation we worked closely together. The crew did an excellent job on their part of the repair, as well as assisting us whenever needed. The yard also provided us with any additional material we required.” This was confirmed by Mr. Anagnostis, “The Hydrex team was very well-organized and we were very pleased. We have never dealt with a similar situation before, carrying out repairs underwater, inside a cofferdam, ” says Mr. Anagnostis. “Everything went smoothly. The vessel is owned by a long time customer of ours so we were pleased that we managed to help them out together with Hydrex.” As a result of the cooperation the fastest and most cost-effective solution was realized for the owner.