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Salvage, Accident Prevention & Emergency Response

Salvage Tech: Motion Monitoring and Forecasting

Posted by on 09 July 2018
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Salvage operations are always plagued by uncertainties. Never knowing for sure how the weather might change, how a stricken vessel is going to move, or what level of risk is posed by a particular course of action hinders salvors’ capabilities to react decisively to casualty situations. It is unlikely that these uncertainties can ever be entirely overcome. But having the ability to monitor with precision the movements of a vessel, and even make predictions about how its movements are likely to change over time, gives salvors a much-needed informational edge.

Motion & Condition Monitoring of the Costa Concordia

One operation in which motion monitoring proved essential was the response to the Costa Concordia accident, when the 925-foot cruise vessel ran aground off Italy’s Isola del Giglio in 2012. After an impact tore a massive gash in its hull, the partially flooded vessel came to rest in an unstable position on a rocky underwater ledge.

There was a pressing need to send in divers, both in the early stages of the operation when survivors were still aboard the vessel, and in the later stages when the recovery of bodies was a priority for families of the victims. But given the instability of the Costa Concordia’s position, there were worries that itmight slip down into deeper waters, pulling any divers aboard at the time with it. Needless to say, the chances of surviving such an event would have been extremely low.

Fortunately, Dutch salvage technology providers Siri Marine were among the first to arrive on the scene. KNect365 Maritime spoke to the company’s commercial director, Marleen Lenting, about how the company’s monitoring and condition systems were able to assist. “What we do is that we place the monitoring equipment on board the vessel as soon as possible,” Lenting says. “[This] enables us to make an assessment of the condition of the vessel – what angle is it placed at, is it steady, is it moving, is there any sign of tortion or deflection?”

Assessing the latter two variables is particularly important, Lenting explains. “People always think a vessel is completely stiff and always stays that way, but it’s actually not – we can tell if there is movement between the front and the back end. That usually indicated if there are soft spots in the hull.” Discovering such soft spots is vital, as they can be an indication that a vessel’s hull may be about to fracture.

In the case of the Costa Concordia, Siri Marine’s motion and condition monitoring systems were able to provide salvors and emergency response crews with the requisite margin of safety to send divers aboard. “We were able to assist the salvage crews by writing daily reports on the condition of the vessel, and on the weather that was coming in,” Lenting says.

As well as providing salvors with better tools for risk assessment, motion monitoring also allows them to respond pre-emptively to situations such as a potential oil spill. “What we claim is that if you know what your vessel is doing, if you know if it’s steady, or if it’s breaking… you can start reacting before the situation gets out of hand,” Lenting says. “Measuring is knowing.”

Of course, in many cases having some degree of forewarning will not be enough to allow salvors to prevent a disaster like an oil spill. But if that happens, accurate data about the status of a vessel can also come in useful. “In later cases that have gone to arbitrage in London,” Lenting says, “salvors have used our reports to say okay – this was the vessel, this was its condition at that stage, this was happening then, this was the weather, and that’s when it broke.”

Combining Data Streams: Motion Forecasting

Starting this year, Siri Marine have added another tool to the informational armoury they place at salvors’ disposal. This time, their objective is to help salvors to predict the movements of their own support vessels, and provide a basis for workability assessments over longer periods.

The company has teamed up with MO4, the developers of what is described as a “next level forecasting” platform. Originally designed for use on offshore projects, MO4’s system pushes back the time horizon on understanding a vessel’s movements by applying “state-of-the-art ship motion” algorithms to weather forecast data. Users are able to input a time and position for a vessel, and receive back accurate predictions about its movements, and the workability of a proposed operation.

Lenting explains that the problem with most of the forecasts used by seafarers is that they reduce complicated datasets into simple values – typically a single wave height and a single wave direction. But the reality of a moving ocean is not so one dimensional. “You can get waves coming in because of the wind, but you can also get waves coming in because of a swell or a current that’s running past,” Lenting says.

MO4’s solution to the problem is to work with the 2D wave spectra provided to weather forecasters, rather than the simplified values forecasters provide to navigators. The wave spectra are combined with the data gathered from sensors on the vessel to provide a more complete picture of its motion. “Every vessel responds differently to the waves and to the weather,” Lenting says. “What we’ve done is that we’ve taken the weather forecasts and we’ve put them into a more useable system… the guys on site can actually input their parameters, they can input the activities they’re doing, and they can increase their workability.”

Lenting explains that integrating MO4’s technology allows Siri Marine’s systems to be used for “big tender proposals” that may stretch over a period of months. When planning a project on this scale, insight of the kind MO4 provides can make the difference between a profitable operation and a commercial disaster. “We’re going more into practical project management,” Lenting says. “With that you need to know okay – what vessels am I going to use? What is their workability at the site of the wreck? How many days am I going to work over the coming months? Because if you calculate those wrong your whole project is going to go bust – you won’t make any money.” In a salvage industry still stretched for profits, such considerations remain paramount.

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