Rachel Lance reveals how she solved the mystery of the H.L. Hunley


The scientist who cracked the 150-year-old mystery of the the sinking of the H.L. Hunley Confederate submarine has revealed the painstaking steps she took to demonstrate what killed its eight-man crew.

Rachel Lance, a biomedical engineer and blast-injury specialist, describes her breakthrough in the forthcoming book In the Waves: My Quest to Solve The Mystery of A Civil War Submarine, due out April 7. 

The Hunley was the first combat submarine to sink an enemy warship, but as soon as it succeeded in its mission targeting the USS Housatonic in Charleston harbor in 1864, it mysteriously sank with all hands lost.

The sub was raised from the ocean floor in 2000, adding to the mystery when it became clear that there was no damage to the hull itself. 

While many theories have been put forward, Lance believes that the crew was killed nearly instantly by the pressure wave from their own torpedo. 

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Rachel Lance

Lance's book is due out April 7

Lance's book is due out April 7

Rachel Lance, a biomedical engineer and blast-injury specialist, describes her breakthrough in the forthcoming book In the Waves: My Quest to Solve The Mystery of A Civil War Submarine , due out April 7

The Hunley's torpedo was not a self-propelled bomb, as we think of them now. Rather, it was a copper keg of gunpowder held ahead and slightly below the Hunley's bow on a 16-foot pole called a spar (pictured)

The Hunley's torpedo was not a self-propelled bomb, as we think of them now. Rather, it was a copper keg of gunpowder held ahead and slightly below the Hunley's bow on a 16-foot pole called a spar (pictured)

The Hunley’s torpedo was not a self-propelled bomb, as we think of them now. Rather, it was a copper keg of gunpowder held ahead and slightly below the Hunley’s bow on a 16-foot pole called a spar (pictured)

The first combat submarine to sink an enemy ship also instantly killed its own eight-man crew (pictured) with the powerful explosive torpedo it carried, new research has found. A new study says a shockwave created by their own weapon was to blame

The first combat submarine to sink an enemy ship also instantly killed its own eight-man crew (pictured) with the powerful explosive torpedo it carried, new research has found. A new study says a shockwave created by their own weapon was to blame

The first combat submarine to sink an enemy ship also instantly killed its own eight-man crew (pictured) with the powerful explosive torpedo it carried, new research has found. A new study says a shockwave created by their own weapon was to blame

The position of the bodies in the submarine gave Lance her first vital clue.

‘Sinkings of modern submarines have always resulted in the discovery of the dead clustered near the exits, the result of desperate efforts to escape the cold metal coffins; to sit silently and await one’s own demise simply defies human nature,’ she wrote in a excerpt of her book published in Smithsonian Magazine.

WHAT KILLED THE CREW? 

The researchers suggest that the crew was killed by a blast of energy as a torpedo was released. 

The shockwave of the blast would travel about 4,920 feet (1,500 metres) per second in water, and 1,115 feet (340 m) per second in air. 

When it crossed the lungs of the crewmen, the shockwave was slowed to about 100 feet (30 m) per second.

While a normal blast shockwave travelling in air should last less than 10 milliseconds, Ms Lance calculates that the Hunley crew’s lungs were subjected to 60 milliseconds or more of trauma. 

Shear forces would have torn apart the delicate structures where the blood supply meets the air supply, filling the lungs with blood and killing the crew instantly. 

It us likely they also suffered traumatic brain injuries from being so close to such a large blast.

‘The crew of the Hunley, however, looked quite different. Each man was still seated peacefully at his station.’

Over the years, various theories about the Hunly have been put forward, including that the ship sank due to its own torpedo or enemy weapons fire, or that the crew became trapped somehow and suffocated. 

‘Any of these theories would require that the crew members, with ample time to see their own deaths coming, chose to spend their last moments nobly in peace, seated at their stations. But that would defy human nature,’ Lance wrote. ‘Something killed these men. Something that left no trace on the boat or their bones.’

Lance, then a graduate student at Duke University, first had to rule out suffocation conclusively. She constructed a precise computer model of the ship to determine its volume, and calculated that the crew would have had a 30- to 60-minute window of warning from the time the first effects of oxygen deprivation became noticeable.

Next, Lance constructed a 1/6 scale model of the Hunely and its torpedo.

Unlike modern, self-propelled torpedoes, the Hunley’s torpedo was a copper keg filled with black powder and attacked to a 16-foot spar on the bow of the submarine,

The sub had to maneuver the torpedo against the hull of an enemy ship and detonate it while still attached to the spar.

Lance had to secure permission from the Bureau of Alcohol, Tobacco and Firearms to legally purchase the amount of black powder she needed for the experiment.

She also had to find a willing farmer with a pond she could use for underwater testing, since officials at Duke balked at her proposal to set off explosive charges in the retention pond on campus.

The experiment nearly ended in disaster when Lance and her boyfriend were driving with 20 pounds of black powder in the trunk of her car, after a serious crash on the highway right in front of them.

Lance slammed on the brakes and narrowly avoided being rear-ended by the truck behind her, a collision that would have likely triggered a deadly explosion.

Finally, Lance was ready to carry out the experiments on her scale model of the sub, which she dubbed the CSS Tiny. 

‘We set off as many charges as we could before the sun began to set on the pond. Blast after blast, we captured and saved the waveforms. I was thrilled to see that the readings looked consistent,’ Lance wrote.

‘And like the actual Hunley, the scale-model Tiny refused to show any damage itself, even after repeated blasts, even as it transmitted the pressures inside.’

The data showed that the blast wave from the explosion passed through the ship’s hull and then bounced around on the inside of the cramped submarine, with enough force to be lethal. 

‘My analysis showed that the amount of pressure ricocheting around inside the metal tube, combined with the quick rise time of the wave, would have put each member of the Hunley’s crew at a 95 percent risk of immediate, severe pulmonary trauma,’ Lance wrote.

Lance believes that death would have been nearly instantaneous for the crew of the Hunley.  

This graphic reveals the Hunley submarine's final moments as it drove its spar-based torpedo into the hull of a Union blockade ship

This graphic reveals the Hunley submarine's final moments as it drove its spar-based torpedo into the hull of a Union blockade ship

This graphic reveals the Hunley submarine’s final moments as it drove its spar-based torpedo into the hull of a Union blockade ship

The Hunley's successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived

The Hunley's successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived

The Hunley’s successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived

The Hunley's first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour

The Hunley's first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour

The Hunley’s first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour

Lance has previously described blast-lung as ‘the hot chocolate effect.’ 

The shockwave of the torpedo blast would travel about 4,920 feet per second in water, and 1,115 feet per second in air.  

Lance said that when it crossed the lungs of the crewmen, the shockwave was slowed to about 100 feet (30 m) per second.

While a normal blast shockwave travelling in air should last less than 10 milliseconds, Lance calculates that the Hunley crew’s lungs were subjected to 60 milliseconds or more of trauma.

THE H.L. HUNLEY’S DOOMED TRIPS

The Hunley’s successful but doomed final mission was actually its third trip. 

The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived.

In October 1863, designer H.L. Hunley led another eight-man crew who planned to show how the sub operated by diving under a ship in Charleston Harbor.

They never surfaced, but the sub was found weeks later and brought back to the surface. 

That crew was interred in graves that ended up below The Citadel’s football stadium for 50 years. 

‘When you mix these speeds together in a frothy combination like the human lungs, or hot chocolate, it combines and it ends up making the energy go slower than it would in either one,’ Lance added. 

‘That creates kind of a worst case scenario for the lungs.’

Shear forces would have torn apart the delicate structures where the blood supply meets the air supply, filling the lungs with blood and killing the crew instantly. 

It us likely they also suffered traumatic brain injuries from being so close to such a large blast.  

The Hunley’s first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour.

The Hunley delivered a blast from 135 pounds of black powder below the waterline at the stern of the Housatonic, sinking the Union ship in less than five minutes. 

Housatonic lost five seamen, but came to rest upright in 30 feet of water, which allowed the remaining crew to be rescued after climbing the rigging and deploying lifeboats.

The Hunley was raised from the bottom of the ocean in 2000, and initially, the discovery of the submarine only seemed to deepen the mystery.

 The Hunley was raised from the bottom of the ocean in 2000. The 75,000-gallon tank of water and chemicals that houses the vessel (pictured) is drained three times a week for several hours to allow restoration work to take place

 The Hunley was raised from the bottom of the ocean in 2000. The 75,000-gallon tank of water and chemicals that houses the vessel (pictured) is drained three times a week for several hours to allow restoration work to take place

 The Hunley was raised from the bottom of the ocean in 2000. The 75,000-gallon tank of water and chemicals that houses the vessel (pictured) is drained three times a week for several hours to allow restoration work to take place

Pictured is the submarine

Pictured is the submarine

The Hunley's successful but doomed final mission was actually its third trip

The Hunley's successful but doomed final mission was actually its third trip

When the submarine was raised in 2000, the crewmen’s skeletons were found still at their stations along a hand-crank that drove the cigar-shaped craft. They suffered no broken bones, the bilge pumps hadn’t been used and the air hatches were closed

HOW THE HUNLEY SUBMARINE MOVED 

Researchers announced in June that they had finally cracked how the submarine was propelled through the water.

Hidden underneath the rock-hard stuff scientists call ‘concretion’ was a sophisticated set of gears and teeth on the crank in the water tube that ran the length of the 40-foot sub.

These gears enabled the crew rotating the crank to propel the sub faster by moving water more quickly through the tube, conservator and collections manager Johanna Rivera-Diaz said.

The biggest surprise for Rivera-Diaz? Discovering that some of the men wrapped the crank handle in thin metal tubes covered with cloth to try to prevent blisters.

‘You get really concentrated on a specific area working every day. I was finishing the crank system. One day, when I was through, I just stepped back and “Wow, this looks amazing”,’ she said. 

The crewmen’s skeletons were found still at their stations along a hand-crank that drove the cigar-shaped craft. 

They suffered no broken bones, the bilge pumps hadn’t been used and the air hatches were closed. 

Except for a hole in one conning tower and a small window that may have been broken, the sub was remarkably intact. 

The eight crew members were buried in an elaborate ceremony at a Confederate cemetery in Charleston in 2004.

They were the sub’s commander, Lt George Dixon of Alabama, James A Wicks, a North Carolina native living in Florida, Frank Collins of Virginia, Joseph Ridgaway of Maryland and four foreign-born men about whom less is known.  

One is still only known as ‘Miller.’

The Hunley’s successful but doomed final mission was actually its third trip. 

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived

The HL Hunley (artist's impression) fought for the confederacy in the US civil war and was sunk near North Charleston, South Carolina, in 1864 by its own torpedo

The HL Hunley (artist's impression) fought for the confederacy in the US civil war and was sunk near North Charleston, South Carolina, in 1864 by its own torpedo

The HL Hunley (artist’s impression) fought for the confederacy in the US civil war and was sunk near North Charleston, South Carolina, in 1864 by its own torpedo

Two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation

Two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation

Two scientists have spent the past 17 years collecting the crew’s remains and restoring the vessel as part of a painstaking cleanup operation

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived.

In October 1863, designer HL Hunley led another eight-man crew who planned to show how the sub operated by diving under a ship in Charleston Harbor.

They never surfaced, but the sub was found weeks later and brought back to the surface. 

That crew was interred in graves that ended up below The Citadel’s football stadium for 50 years.   

Two scientists have spent the past 17 years collecting the crew’s remains and restoring the vessel as part of a painstaking cleanup operation.

They patiently removed a century and a half of sand, sediment and corrosion from the historic submarine.

Their goal is to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current.

This gradually softens the concrete-hard buildup of sand, mud and shells that built up inside the vessel during the 140 years it was buried off Sullivan’s Island, so that the debris can be removed later.

Two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation (pictured)

Two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation (pictured)

Two scientists have spent the past 17 years collecting the crew’s remains and restoring the vessel as part of a painstaking cleanup operation (pictured)

Pictured is the Hunley as it was removed from the ocean floor in 2000. Scientists have since spent 17 years restoring the vessel

Pictured is the Hunley as it was removed from the ocean floor in 2000. Scientists have since spent 17 years restoring the vessel

Pictured is the Hunley as it was removed from the ocean floor in 2000. Scientists have since spent 17 years restoring the vessel

Since the submarine was found and removed from the ocean (pictured), the researchers' goal has been to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current

Since the submarine was found and removed from the ocean (pictured), the researchers' goal has been to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current

Since the submarine was found and removed from the ocean (pictured), the researchers’ goal has been to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current

They drain the 75,000-gallon tank of water and chemicals that houses the vessel three times a week for several hours, at the Confederate sub’s home in North Charleston, South Carolina.

Then, they go to work in full protective gear, bent around nooks and crannies, gingerly chipping the grime off the HL Hunley.

It took one year to remove all the crud from its hull, and nearly two more to clean out the much smaller crew compartment.

The sub itself is only four feet in diameter. Eight schoolchildren can barely cram themselves into a replica nearby at the Warren Lasch Conservation Centre.

The Hunley submarine was raised from the bottom of the ocean off the coast of North Charleston, South Carolina, in 2000

The Hunley submarine was raised from the bottom of the ocean off the coast of North Charleston, South Carolina, in 2000

The Hunley submarine was raised from the bottom of the ocean off the coast of North Charleston, South Carolina, in 2000