E. C. Singer, one of the investors in the Hunley, was the nephew of the man who invented the sewing machine. It is interesting to note that a spool of rope (similar to the spools of thread used on a sewing machine) was used in the torpedo's rigging.

Illustration of the H.L. Hunley submarine
with its bow-mounted spar torpedo.
(Image courtesy of Dan Dowdy).

The H.L. Hunley torpedo was originally designed as a percussion torpedo which would be dragged by a line behind the submarine. The H.L. Hunley would dive under the target vessel, while towing the torpedo on the surface towards it. Once it made contact with the hull of an enemy ship, it would then explode sending the ship to the murky bottom. But heavy seas and currents often made this a danger for the H.L. Hunley. Having a copper cylinder loaded with 90-plus pounds of explosives attached to a line and bobbing around on the surface risked blowing up the H.L. Hunley itself - something that almost happened. This may have been one of the reasons why the H.L. Hunley was eventually fitted with a bow-mounted spar torpedo.

The Spar Torpedo Concept:

Because of the problems with the towed torpedo, a new design was needed for the H.L. Hunley submarine. This became the spar torpedo. The spar torpedo was designed to be rammed into the hull of an enemy ship. The torpedo was fastened to the end of the spar and fitted with a barb on its end. The idea was to ram the spar torpedo into a target and then back away, causing the torpedo to detach from the spar. A line from the torpedo to the submarine would spool out as the sub reversed its course. Once the submarine was at a safe distance, the line would detonate the warhead.

Hypothetical drawing of the spar torpedo.
The design of the spar is yet another mystery solved when the H.L. Hunley was located. For many years it was believed that the spar was a 22-foot yellow pine boom. However, the discovery of the H.L. Hunley revealed that the spar was made of iron, was mostly hollow, and measured 17 feet in length. It was also originally thought to have been affixed to the upper portion of the bow. But archaeologists working on the H.L. Hunley project discovered that the spar was mounted with a y-shaped joint at the bottom of the bow. The wooden boom may have also been used, but only as a support for a line holding the lower spar in place.

Sketch of the H.L. Hunley on the docks in Charleston made by Conrad Wise Chapman on December 2, 1863.

Interestingly, the spar torpedo concept has always been considered a potential mode of attack as shown in the Conrad Wise Chapman sketch dated December 2, 1863.

On February 17th, 1864 this innovative design proved successful - a first in maritime history - when the H.L. Hunley sank the USS Housatonic. Furiously cranking the propeller, the eight-man crew rammed their spar torpedo into the side of the enemy ship. As the sub pulled away an explosion assured them victory was finally at hand. The Union ship sank fast. What happened next is a mystery that remains to this day….

Related Pages:

Innovation & Evolution
   American Diver
   SUCCESS: H.L. Hunley
The Hunley Revealed
   The Spar
H.L. Hunley Simulator

Copyright (c) 2014 Friends of the Hunley.
All Rights Reserved.