Hydrex's Doubler Plates Keep Ships Sailing

Underwater repair specialist Hydrex says when hull damage leads to the classification society to only allow temporary repair, there is a practical solution that allows ships to continue operations until a permanent repair can be scheduled.

Recently called upon to inspect damage to the stern thruster area of a 195m ro-ro ship during a scheduled stop in Antwerp, the Hydrex investigation revealed a large crack in the welding seam on the edge between the hull plating and the thruster tunnel.

To repair the vessel, Hydrex was able to fabricate a 600mm x 300mm doubler plate, on-site. After preparation of the area around the crack, a certified Hydrex diver/welder welded the doubler plate in place and the ship was able to continue.

This, like most such projects, was relatively simple for the Hydrex team. However, the repair to a tanker in the United Arab Emirates was somewhat more challenging. The owner’s representative had requested an emergency repair while the ship was berthed in Dubai.

“Hydrex’s fast response center carries large stocks of the necessary equipment and materials for such repairs, so repairs can usually get under way almost immediately,” explains Production Executive Dave Bleyenberg.

On this occasion, on arrival on site, the Hydrex team leader discussed the likely scope of work with the ship’s superintendent while the divers began their initial inspection. It soon became apparent that there were large indents, a total of 12 cracks, and several punctures in the hull flat bottom shell plating – a considerably larger repair than at first anticipated.

Having agreed the repair proposal, diver/technicians set to work drilling arrest holes at the extremities of each crack, to prevent any further spreading, and taking careful measurements for two doublers that would exactly fit the dented shape of the hull.

The plates were fabricated on site, one measuring 1000mm x 700mm and the other 700mm x 600mm, and fitted and secured by the Hydrex underwater team.

The speed of Hydrex’s response meant that the ship’s tight schedule could be maintained, and a permanent repair carried out at a more convenient time and location.

“As with all our repairs, both emergency and permanent, Hydrex teams operate to the highest standards to ensure the safety of all ships,” says Bleyenberg. “Repairs of this kind can only be done successfully by trained diver/technicians who have the relevant know-how and experience to resolve all of the technical difficulties encountered during underwater operations. Our technical staff at all offices undergo comprehensive training allowing them to perform a wide range of operations, quickly and at high quality levels, avoiding unnecessary loss of time.”

Hydrex’s on-site hull repair services include renewal of small and large areas of damaged hull plating, above or below water level, as required. With an expanding network of fully-equipped offices and support bases, the repair teams can be mobilized rapidly to virtually any location. All repairs are carried out in accordance with the company’s class-approved procedures for welding damaged shell plating.