Spar Torpedo Reveals New Info About How Hunley Sank A Ship

By Scott C. Boyd
(April 2013 Civil War News)

The copper sleeve that held torpedo remains held onto spar by nut and bolt. Torn copper to their right shows how detonation of the  torpedo pushed the sleeve down on spar. Also note seam on spar tube.

CHARLESTON, S.C. – The exciting discovery of a damaged copper sleeve at one end of the spar on the Confederate submarine H.L. Hunley has overturned conventional wisdom about how the vessel became the first submarine to sink an enemy vessel in combat.

The new information was revealed at a Jan. 28 press conference at the Warren Lasch Conservation Lab where the recovered submarine is being conserved.

Additional details about the Hunley’s spar have subsequently come to light and testing is planned to gather more data about why the submarine may have sunk after its history-making attack.

Spar Torpedo

The damaged sleeve was part of the copper case holding the gunpowder charge of the explosive torpedo attached to the spar, a 16-foot metal tube (details below). This spar torpedo was the Hunley’s only weapon.

The conventional explanation for how the spar torpedo worked was that the Hunley rammed the torpedo, which had a barb on its end, into the USS Housatonic’s hull, attaching the barbed torpedo. Then the Hunley backed away and the torpedo detached from the spar, remaining impaled in the hull.

A rope lanyard was supposedly attached to the torpedo and wound on a spool attached to the Hunley’s exterior. After the submarine backed up and reached the end of the rope, the taut lanyard would then pull and detonate the torpedo.

Hunley chief conservator, Paul Mardikian said not only was part of the torpedo casing on the spar, but it was attached with a nut and bolt.

This demonstrates that the torpedo was never meant to come off the spar, contrary to the conventional understanding of how it worked.

Mardikian said he learned something was on the end of the spar when he X-rayed it about 10 years ago. He originally thought the sleeve was made of lead until he removed the concretion from the spar last summer and discovered it was copper and was part of the torpedo itself.

“The new findings on the spar change the entire configuration,” said Maria Jacobsen, chief archeologist for the Hunley project. She recently presented the new data to the Hunley’s owners, the U.S. Navy.

“The conventional wisdom [about how the spar torpedo worked] seemed very suspicious and very unlikely to most of us,” she said. “It seemed like an unlikely way of implanting a torpedo,” especially if the target is a ship’s hull sheathed in metal to prevent barnacles, as was a common practice.

One of Jacobsen’s researchers found a technical drawing in the National Archives of a torpedo labeled as the one used by the Hunley to sink the Housatonic.

The torpedo was designed by the Singer Company. It had 135 pounds of black powder, with three spring-loaded triggers in the center, according to the drawing.

Jacobsen said the torpedo was detonated by a lanyard probably pulled somehow from inside the submarine.

New Details

Mardikian gave Civil War News many new details about the spar itself.

The spar is 16 feet long and hollow, made from a metal sheet about 3 or 4 millimeters thick folded into a tube shape. Its outside diameter is about 2.5 inches. A seam down its length is visible now that the concretion has been removed.

The spar was made from two tubes joined by a coupling on the outside. Additionally, a chunk of steel was riveted inside at the joint to strengthen it.

The sleeve of the torpedo cylinder was secured with a vertical nut and bolt at one end of the spar.

On the other end, the spar was slid onto a solid metal rod and attached with a vertical nut and bolt.

That rod had a U-shaped end that attached to a yoke on the Hunley’s lower bow with a horizontal nut and bolt. This allowed the spar to be raised vertically for attaching or removing the torpedo.

Previously people could only speculate about factors such as the size of the powder charge in the torpedo and how far the Hunley was from the Housatonic when it exploded, according to Jacobsen.

Now they finally have some of the data needed to mathematically model the effect of the torpedo’s underwater explosion. That effect on the submarine’s hull and on the crewmen inside will be calculated.

Physical scale-models may also have to be used at some point for “controlled explosive testing,” she said.

Further data needed includes the exact condition of the submarine’s hull, which may give clues to the explosion’s impact.

The hull is still covered by concretion from its 136 years under the sea. Safely removing this concretion is Mardikian’s next big task.

The Hunley disappeared on Feb. 17, 1864, after sinking the U.S.S. Housatonic, a wooden steamer warship, just outside the entrance to Charleston Harbor. It was located in 1995 near the Housatonic wreck and was recovered in 2000.

For more information visit Friends of the Hunley at

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