Hydrex Breaks Ground with Repair

A 262 ft. (80-m) containership from Antwerp had an unfortunate collision in Boston, Mass. with some rocks and ended up with a large number of tears, ranging from one to seven meters, to its flat bottom.

Hydrex was called in to propose solutions for the major repair.

A team of eight was sent from Hydrex to begin the work in liaison with a local company, which provided backup, equipment and consumables. The work required five different kinds of patches to be welded to the flat of bottom. The largest one was 47 x 4 ft. (14.5 x 1.3 m) and weighed approximately 1,700 kg. Heavyduty rigging equipment was required to get this into position. The technical work of how to securely attach this to the ship was done by using a total of 170 screw dogs, an alternative procedure Hydrex has utilized around the world. A total of two-km of underwater weld seams were performed by divers to get all the plates securely attached.

The plates were designed with two concave surfaces on the inside meeting in the middle. This method allows the inside of the plate to press against the damaged area and increase the surface contact and pressure with the flat of bottom, ensuring better contact. Seals were placed all around the contact area and the empty space behind the plates was filled with concrete in order to stabilize it, prevent vibrations, and prevent the liquids in the fuel tank and the ballast tank mixing as the tear ruptured between two spaces. Due to the extent of the damage, requirements for repairs set by class and coastguard were unusually high. Normally, plates of eight-mm thickness could be used when there was only one such tear, but this required 15-mm thickness throughout. Coastguard not only gave the crew authorization for the ship to sail back to Europe, but also allowed them to load up the ship again.

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Maritime Reporter Magazine, page 13, Jun 2001

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Maritime Reporter

First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.