Sea change for salvage operations

‘MS Riverdance’ beached at Blackpool. Photo: Susan Noble ‘MS Riverdance’ beached at Blackpool. Photo: Susan Noble

There’s been a shift, Adrian Scales of Brookes Bell, told 'MJ': “The industry is now moving away from prescribed salvage methodology to a vessel-by-vessel approach,” one that takes into consideration the “evolving” nature of a project’s challenges.

However, this may not have been plausible without the advent of new technologies.

Scales explained that rather than take a pen, paper and tape measure to every single piece of metal, machinery or pipe, “new laser scanners can move through half a dozen areas on a vessel, quickly recording the ship’s structure, where the equipment is, where there is collision damage or rock penetration, and return a full 3D representation of the damaged ship.”

“Then you can easily compare this against the ship’s plans... and work out what structure needs to be strengthened or reinstated before you start repairs.”

Taking that one stage further, Scales advocated “using drones to take an overview, so you have both the internal and external 3D computer models using this very clever photogrammetry technology”. He went on to say: “Pull this all together, and you have something that provides a detailed reference of where the damage is, allowing you to work through the options on a cost-saving basis.”

He added this methodology has an inbuilt advantage: “Unlike traditional manual methods, if you miss a measurement you later find you need, you can go back in and measure it off the computer – it’s always retained.”

Of course during salvage operations there is a continuous monitoring operation on the structural integrity of the vessel. “However,” he said, “the nature of the work means dealing with the unexpected and challenges are often not evident until operations are underway.”

“Damage is not always immediately visible, and weather events can shift the substrate under the hull, or cause the vessel to sustain additional structural damages. For example in the [2008 grounding] of MS Riverdance, shifting sands caused the vessel to roll over onto its side before a refloat could be attempted.”

Therefore “a detailed view of the ship’s physical strengths and weaknesses makes a better foundation for any necessary adaptations to the ongoing planning”.

These new techniques should draw attention, not least because despite their sophistication, they don’t cost a great deal: “At heart, it’s a series of laser scans or still photographs built into a 3D map,” said Scales.

Moreover, they are proving to have a more extensive remit than assumed; he added giving potential salvage teams an overview of the task results in a number of different approaches, some of these extremely innovative.

For example, one recent project that left a hull sitting on the seabed, too deep for an air dive team to intervene, used ROVs to cut openings in the hull and insert lifting pins. “This is something new, and I’m sure we’ll be using it again in future,” said Scales.

Other developments are changing how investigators reconstruct an incident: “AIS is promulgating data everywhere. It’s generally free to access, so as you are taking statements from the crew, you can run through what actually happened, how the ship moved and responded.” Whilst more time-consuming, he also explained that Computational Fluid Dynamics (CFD) analysis has recently helped reveal the physics behind grounding, internal air flow as well as contact incidents.

“These technologies assist in building a more convincing, realistic case, allowing you to take it to the forensic level and demonstrate the pattern of events all the way through from start to finish,” he explained.

However, he’s careful to point out that these techniques are far from mature and still very much at the ‘early adoption’ stage: Brookes Bell’s team has only recently started trialling airborne drones. “These approaches are by no means fully evolved... however, the technology is improving along with the ability to better manipulate the data, so we are beginning to see the potential for the increased use of this technology on most if not all of our projects in the future.”

It is, said Scales, an exciting time, and one that’s in keeping with the new accent on environmental stewardship, entirely compatible with a new attitude from ship owners “that’s changed from just wanting the job done, to wanting the job done well.”

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