[FAQ] What Happens When A Huge Ship Sinks?

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Credit: Timur M/Unsplash

What precisely should you do in the event of a shipwreck, and how can you avoid catastrophic pollution? 

What happens next?

At 3:24 am in the Atlantic Ocean, a catastrophe unfolds across the moonlit waters.

The coastguard receives the distress call.

Helicopters lift the flailing crew members to safety, while support boats unload any cargo that hasn’t already tumbled into the sea.

If a fire breaks out, the vessel will become a giant pressure cooker.

Although our MS Seascape is a hypothetical ship, its situation is far from uncommon.

Abandoning the ships is rarely an option.

The risks of oil and fuel leaks mean it is now standard practice to try to salvage them and fix any environmental damage.

But the costs are astronomical: the Costa Concordia, which ran aground off Genoa, Italy in 2012, became the most expensive wreck removal in history, costing more than $1bn, and taking 350 salvage workers almost three years.

There’s no cookie-cutter approach to salvage: each operation will vary depending on location, water depth, weather, equipment and sensitivity of the surrounding environment.

So what to do with our hypothetical MS Seascape?

Step 1: Contain spills and remove fuel

The risk posed by MS Seascape, loaded with potentially explosive car batteries, is not dissimilar to that of the 200-metre Felicity Ace, which caught fire in the mid-Atlantic before sinking to an unsalvageable 10,000ft: it is suspected that the 281 EVs onboard may have sparked, or at least accelerated, the blaze.

To avoid this fate, a local salvage company gets involved, one of a few dozen operators around the world poised to rush to the scene of a maritime disaster.

Its first objective is to save the vessel and return it to service.

A vessel’s location has a huge bearing on how quickly the operation unfolds.

The Rena, a container ship that grounded off the coast of New Zealand, had to wait several weeks for equipment to arrive from Singapore – during which time the hull broke apart.

In the meantime, a specialist team begins bleeding its 20-plus tanks of more than 300,000 gallons of fuel, as well as potential pollutants such as lubricants, gases and oily water and sludge.

They drill through the ship’s exposed double-walled steel exterior into the fuel bunkers below, inserting pipes to pump out waste to a waiting vessel.

Divers are dispatched to enter the ships’ interior to drain the remaining submerged tanks.

This is a delicate task: removing fuel can destabilise the already precarious ship, so this process can take days, possibly weeks.

Suddenly, a crisis: after days of being strained against the reef by the current, stress fractures appear along the hull.

This dashes hopes of returning the MS Seascape to service – the cost of recouping would now be more than the value of the ship itself.

The mission transitions from salvage operation to wreck removal and the real work begins.

Step 2: Slice the ship apart

After 10 days, the ship’s fractures threaten to separate the wreck. Numerous engineers, crane operators, firefighters, labourers, divers, and architects must work swiftly.

To clear the deck and streamline the procedure, they cut away the lodging building. Using explosives, such as those used on the MSC Napoli, a sizable cargo ship that ran aground off England’s south coast in 2007 and was split in two, is one way to destroy the ship. However, this would be disastrous for the delicate coral environment that exists beneath the wreck.

The cleanup crew instead decides to use a strong cable of diamond-encrusted wire, which can cut through inches of steel. The saw is put onto a specially-made frame that is carried to the wreck site using cranes. Its two legs are rigged into the seafloor on either side of the wreck over the course of two days. The wire is cycled quickly through a system of pulleys inside the frame before being lowered, like a guillotine, into the metal mass and cutting through it with an audible roar. One cross-section can take up to 12 hours to cut, yet because of the saw’s surgical accuracy, the reef underneath is just slightly scratched. Additionally, it has the ability to cut around the gasoline tank and between parked cars on lower decks to prevent as many from falling into the water. Not only is fuel a concern to the environment, but ships also contain a staggering amount of toxic materials, including asbestos in the walls, antifouling chemicals, lead entrenched in the paint, mercury, and polychlorinated biphenyls (PCBs) woven into the electrics of older ships. Hulks left to decompose in the ocean will gradually leak these chemicals out. After more than 80 years, a German vessel that has sunk is still discharging chemicals into the North Sea.

Step 3: Remove sections and take them ashore

The MS Seascape is now encircled with vessels and equipment ready to intervene as pieces of the wreck are shorn off.

First, the floating sheerleg: a huge crane on a buoyant platform, capable of lifting 7,000 tons.

It is a mechanical island with an accommodation block for the dozens of workers who will be at sea for weeks dismantling the wreck.

The crew will slice the ship into eight pieces.

Before the rear segment is cut free, support vessels weld enormous air-filled metal boxes called caissons to its exposed starboard side.

These are partly filled with water, adding weight that rotates the stern upright when it is cut free.

Not all wrecks would need the same approach.

Some with relatively minimal damage, such as the Costa Concordia, can be patched up, fully refloated with caissons, and then towed away.

Others have to be dredged up from the seafloor, such as the X-Press Pearl, whose nitric acid load caught fire off Sri Lanka in 2019 and caused the ship to sink to 68ft – along with its cargo of 50bn plastic “nurdles”, which swamped Sri Lankan beaches.

Divers, aided by remotely operated underwater vehicles, locate lost cars and other metal debris, feeding this information to a barge fitted with underwater magnets and mechanical grabbers.

Two months after the ship ran aground, no trace remains of the MS Seascape in the ocean – but the work continues.

Step 4: Strip down the ship

The MS Seascape’s components are waiting to be dismantled back on dry soil. The ship must be destroyed in one of 46 authorised yards located in Europe, Turkey, and the US because it is EU-flagged.

This indicates that it would be handled in accordance with more stringent rules than ships at south Asian shipbreaking beaches, where 70% of all ships worldwide end their seagoing existence. As a result of laxer restrictions in these places, dozens of labourers die every year and the ecosystem is negatively affected incalculably as contaminants wash up on beaches and into the ocean. However, at the dry dock in Italy where most of the MS Seascape ends up, waste is supposed to be contained. Over several months, the ship is stripped back to basics: sheets of asbestos, wiring, equipment and furniture are removed until only the steel husk remains. This is where most of the ship’s value now lies. Efficient smelting operations can recycle almost all a ship’s steel: about 90% of the material in the Costa Concordia was recycled.

Back on the reef, rehabilitation has begun. The water is monitored for residual pollutants, and teams begin planting nursery-grown coral into the shattered reef. This will take years: a decade after the Costa Concordia capsized, damaged seagrass meadows are still being restored.

Now reduced to molten steel, some of the MS Seascape might be forged into yet another ocean-going colossus. As shipbuilding ingenuity grows, so will the effort, costs – and innovation – required to salvage these leviathans at sea.


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Source: The Guardian

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