Inside the design of Charybdis, a monster of a ship bringing wind turbines to the ocean

In a south Texas shipyard, a large vessel named after a horrifying mythological sea monster is now more than 75% finished. The ship is called Charybdis and when it’s complete—perhaps late next year or in early 2025—it will have an important job to do: installing giant offshore wind turbines that will provide clean electricity to the U.S. grid. In fact, the vessel will be able to pull off a specialized trick that an average ship can’t accomplish. It will be capable of lowering legs down to the seafloor and then raising itself up totally out of the water, so it becomes a stable platform in the ocean. 

Because wind turbine parts are so big, the ship needs to be big. Charybdis will measure 472 feet long, 184 feet wide, and host a crew of more than 100 people. The wind turbine blades it will carry will be 354 feet long (longer than the 100 yards of a football field), and each turbine needs three of those, plus the tower sections, and has a nacelle that weighs more than 550 tons. A nearly 73-foot-wide platform at one end of Charybdis will provide a spot for a helicopter to take off and land. 

Dominion Energy, the company making the vessel, says that it will be able to carry components for four turbines. The large blades will be housed in a horizontal racking system at the opposite end of the ship as the helicopter pad; the tower sections will be stored vertically on deck, rising up high. A crane with a nearly 427-foot-long boom will be able lift the mammoth parts into place when installing a turbine. 

“Charybdis is great—it’s an amazing vessel,” says Claire Richer, the director of offshore wind for American Clean Power. “We have a huge need for more vessels. There’s a shortage of vessels to be able to build all the offshore wind that we aspire to, and so Charybdis is an important piece of that.” 

The Charybdis will be able to jack itself up out of the water at a rate of about two feet a minute, thanks to four long legs and a rack-and-pinion system. Those legs actually pass through the ship itself, so that when the ship is floating in the water, the four legs tower upwards. 

Wind turbine installation vessels aren’t the only ships with the special ability to be able to jack up and become platforms out of the water—Richer notes that jack-up vessels are “common” in the offshore oil and gas industry, but Charybdis is still notable. “The Charybdis is a huge jack-up in terms of just its size and its length,” she says. 

“It’s pretty incredible to be on the vessel, I’ve heard, while it’s jacking up,” she adds.

The Jones Act

Another important thing to know about Charybdis, which has a price tag of $625 million, is the fact that it’s being made in the U.S.—it’s the first wind turbine installation vessel created here. That’s key, because it will be able to comply with a maritime law from 1920 called the Jones Act. The law affects which ships can carry goods from point to point in the US. (And a wind turbine installation site in the water, once a foundation is down on the seafloor, counts as a point.) Those ships need to be “built in the United States, owned by Americans, and crewed by Americans,” Richer explains. A ship that meets those criteria is what’s known as “coastwise-qualified.”

“The Charybdis is the first coastwise-qualified wind turbine installation vessel that has ever been built in the United States,” Richer says.

While that distinction sounds like just a salty nugget of maritime trivia, the fact that the Jones Act exists, and U.S.-made installation ships like the Charybdis aren’t yet in service, affects the way companies need to build offshore wind farms in the U.S. For example, a wind farm called South Fork, which recently sent its first electricity to New York, is using a Dutch installation vessel called the Aeolus to build its turbines. But that foreign ship can’t go to a U.S. harbor, pick up wind turbine components, and then build them at sea. 

Instead, an American barge and two tugboats have to shuttle the goods back and forth, and then transfer the hefty wind turbine parts to the Aeolus. Something similar happens in Massachusetts, where Vineyard Wind is under construction, and barges bring equipment to a different vessel, the Sea Installer, which has a Danish flag. In other words, because of the Jones Act, foreign wind turbine installation vessels can build wind turbines in U.S. waters, but not transport the components from point to point. The Charybdis will finally be able to do all that itself, sailing back and forth to get the goods and then jacking up out of the water to become a platform when it needs to install the turbines.

The Jones Act, which is now over a century old, is “well-intentioned and does some good things for the U.S.,” says Kris Ohleth, who directs the Special Initiative on Offshore Wind, an independent and nonprofit policy think tank focused on the industry. “Essentially, it protects U.S interests in the maritime sector.” 

But using a system in which barges bring components out to an installation vessel, and then transfers them to it, means that “the logistics are really challenging,” Ohleth says. “It’s just more costly and time-consuming to build this new technology because of this antiquated act.” 

Ohleth says that the Charybdis is “hugely positive.” But, she adds, “it’s not enough to move the needle on what is needed for offshore wind construction by far—if that vessel is servicing one project, we’re looking at like half a dozen projects in simultaneous construction off the coast of the U.S. every summer, ideally, to meet our targets.” 

“We could use like 10 more of those,” she says.

Dominion, the ship’s maker, plans to use the ship to build a large development, Coastal Virginia Offshore Wind, which will have 176 turbines. 

Between Scylla and Charibdis 

As Charybdis is being built, the offshore wind industry has been feeling some “growing pains,” says Ohleth, who cites financial factors like high interest rates and inflation as problems. Josh Kaplowitz, an offshore wind policy expert, also mentions the pandemic, the war in Ukraine, and the price of steel as issues, too. “There are projects that are facing some challenges as a result, and we need to look for policy solutions that help get these projects over the hump,” he says.

For example, a company called Orsted recently said it was canceling two projects, called Ocean Wind 1 and 2, and four others are in flux. Two projects are ongoing—Vineyard Wind and South Fork Wind—and others are still planned for the future. 

As for Charybdis, its name refers to a mythological Greek sea monster that’s associated with a dangerous whirlpool; another monster, Scylla, lurked near Charybdis, and both were hazards for sailors. In the real world, the ship Charybdis will actually be a counterpart to an existing ship called Scylla. Other ships also have monstrous names, such as Hydra, Leviathan, and Kraken, all from a company called Seajacks, which Dominion is working with on Charybdis. “Their naming convention seems to be off of these sea-monster-esque names,” says Jeremy Slayton, a spokesperson for Dominion. “If it works, don’t change it.”