The Spar Apparatus

T he Hunley's torpedo system is one of the submarine's most important features and one of the least understood.  Details of the rig slowly emerged as the components of the Hunley were cleaned and revealed. 
     (The most recent material is at the end of this pop-up.)


Historical Descriptions
This is a summary of the historical source information related to the Hunley's torpedo.  It's not exhaustive but captures the pertinent information.  The quoted text is from The H.L. Hunley in Historical Context web page unless otherwise noted.   

     The original Hunley concept was to tow the torpedo on a long line, dive under the target ship and draw the charge against the target's hull.  This approach was abandoned when the torpedo drifted "too near the wrong boat" as Alexander recounted, perhaps euphemistically, in 1902.  In the same memoir he describes the new approach this way: "We then rigged a yellow pine boom, 22 feet long and tapering; this was attached to the bow, banded and guyed in each side. A socket on the torpedo secured it to the boom."  In 1925, Corporal Daniel McClaurin provided a slightly different description: "As I recall, the torpedo was fastened to the end of an iron pipe, about two inches in diameter and twenty to twenty-five feet in length, which could be extended in front and withdrawn at ease by guides in the center of the boat to hold it in place."  The apparent discrepancy between the two descriptions is partly alleviated when Alexander's drawing, published with his memoir, is examined.  It notes the "butt end of torpedo boom" attached to the top of the bow, drawn with a stylized wood grain, and a smaller, un-referenced object attached to the bottom of the bow and angled up (see image #53544 on or linked from the Submarine H.L. Hunley images page).  The many years passing between the 1864 events and these reminiscences makes some details suspect, but I believe the basic descriptions can be trusted. 
     Accounts differ as to how the torpedo was to be detonated.  Describing the towed torpedo system, Alexander mentions detonators on the torpedo itself, "one of the triggers to touch the vessel and explode the torpedo", a logical approach.  Also describing the towed torpedo, George Gift writes in a letter to his fiancée "The steersman has a string by which he can explode the torpedo by giving it a jerk".  Several accounts that indicate concern the submarine would be drawn into its target when the bow-mounted torpedo exploded imply impact triggers like Alexander's detonators.  This was the approach used for other Confederate torpedo boats.  In 1914 C. L. Stanton quotes Payne's concern "that if he struck a vessel with the torpedo staff projecting horizontally he feared the boat would enter the hole made by the explosion in the ship's side".  Payne's thought "that if the torpedo staff was lowered to an angle of forty-five degrees when the ship was struck the torpedo would explode near the keel, and the Fishboat's bow, striking the solid planking of the ship, would recoil sufficiently to make the machinery effective in backing out of danger".  Stanton continues "I have always felt very certain that the torpedo staff was in this position when the Housatonic was struck....  Besides, when the boat lay alongside the Chicora on the night of 14th of February, I examined it closely".  (Payne's assertion is given credence by the Friends' announcement in January 2013, as discussed below.)  Housatonic crew accounts of the sinking indicate the Hunley was backing off at the time of the explosion, consistent with a lanyard activated trigger like Gift's. Chapman's painting shows what appears to be a spool for such a lanyard.
     The above accounts indicate the angle of the torpedo spar was adjustable.  Alexander gives this account a typical Hunley sortie: "Dixon and myself would ... get the bearings of the nearest vessel as she took her position for the night; ship up the torpedo on the boom, and, when dark, go out, steering for the vessel, proceed until the condition of the men, sea, tide, wind, moon, and daylight compelled our return to the dock; unship the torpedo, put it under guard at Battery Marshall..." (from Virgil Robinson's Southern Historical Papers page).  McClaurin reports that on Feb. 17 "Lieutenant Dixon landed and requested that two of my regiment ... go aboard and help them to adjust the machinery, as it was not working satisfactorily. Another man and I went aboard and helped propel the boat for some time while the Lieutenant and others adjusted the machinery and the rods that held the torpedo and got them to working satisfactorily".  Photographs of the semi-submersible David torpedo boats show a rig that permitted the torpedoes to be lowered below the surface near their targets.  Using such a rig would be difficult and dangerous from the very narrow hatches of the Hunley but McClaurin's machinery may have been intended for that purpose.  It is also possible that Dixon was making adjustments to keep the torpedo stable or at a particular depth.


Historical Images
The Conrad Chapman painting and the purported George Cook photograph both show the lower metal spar and the top-mounted boom but support different interpretations.  
     For background to help understanding the images, the 17-foot-long metal spar recovered with the Hunley consists of a three-foot long solid section attached by a bolt to a long hollow section.  The short section ends in a fitting that was bolted to a bracket at the bottom of the bow as depicted below.  The arrangement allowed the spar to pivot up and down at the bracket. 


 

     Chapman's painting shows the metal spar, although only the short segment closest to the hull, sloping down to rest on the quay.  The upper boom is much more notable, as you can see in the graphic at right.  It appears to be 3 to 4 inches in diameter and perhaps 14 feet long.  The rather complex mechanism that appears to attach it to the hull could be part of a rigging system. 

Hunley's bow from Chapman painting

Hunley's bow from purported Cook photo      The poor-quality (qnd discredited) Cook "photo" has a similar perspective but differs in detail from the painting.  Both the lower spar and upper boom are visible, but the boom appears to be mounted athwart-ships rather than fore and aft as in Chapman.  I may provide a more detailed analysis of the alleged photo in the future.
 
     Chapman's starboard-side drawing implies he actually visited the Hunley on the quay depicted in his painting, which he completed some years later.  The drawing shows the lower spar but not the boom.  Obvious differences in the configuration of the boat shown in the drawing and in the painting indicate a passage of time between the two scenes.

Hunley's bow from Chapman drawing
Hunley bow from Skerrett

     The 1902 Skerrett drawing, included here for completeness, provides yet a different cast.  The upper boom appears to agree with Chapman, although the mounting mechanism appears much less complex.  The lower spar, if depicted, appears to be detached, but there is a line running to it from the upper hull. Detached spar?
 
 
     The relationship among the several depictions of the Hunley briefly discussed above is not known.  Chapman's painting, the purported Cook photo, and Skerrett's drawing clearly show the same scene.  Each includes what appears to be the same sailboat in the background.  Each has a figure standing by the rudder.  Obvious questions arise.  Did Skerrett copy Chapman, or Cook?  Did Chapman use Cook as a model or guide for his painting?  Is Cook an actual photo of the Hunley?  Is it a copy of an early or lost version of the Chapman painting?  I hope to present a more complete evaluation of the Cook photo someday.
 

Archaeological Evidence
The Friends of the Hunley published an updated archaeological site plan (in The Blue Light 10, Nov 2003) showing the location of artifacts found near the Hunley.  The items labeled 1-4 and possibly 5 in the graphic below are identified as associated with the spar.  A three-foot scale sizes the objects.  The Friends published a post- conservation photo of what is probably item 1 or 3 in The Blue Light Volume 42, Winter 2013, identifying it as "part of the spar system, helping hold one of the poles in place".  The "Recovery Operations" paper, linked from my main Hunley page, provides more information about these parts.

Spar-assembly artifacts
The long rod at the top, 6, raised with the spar, was less concreted and appeared at the time to be more recent.  The Friends have said nothing more about it.
     Heavy raised concretion in several places on the bow, seen in released photos of the Hunley, may indicate parts of the rigging system.  Two longer markings could be the straps shown in a similar location in the Chapman painting.  
     The Clemson fade-wrap animation gives tantalizing indications of bumps in the concretion approximately consistent with tie-down points for rigging lines to stabilize the spar.  I've only done preliminary analysis, but I've assumed such tie-downs for the animated line drawing and for my Hunley poster.  (Photographs of the hull after it was cleaned of concretion show no sign of these bumps, raising doubts in my mind of a system of stays.)
     There are two bits of published information that likely pertain to the torpedo lanyard spool shown in the Chapman painting.  The 2006 DENIX report "Conservation of the H.L. Hunley and its Associated Artifacts" mentions a small crank and stuff box removed from hull panel CT3.  The Summer 2009 Blue Light (#32) includes a wire frame 3D rendering of that plate, for the first time showing the location of this mechanism.  (A photograph of this plate published on the Low Country Digital Library, linked from my main Hunley page, clearly shows this crank.) This location, actually high on the hull between the snorkel pipes, is consistent with Chapman's depiction.  My Hunley plan includes a spool in this position beginning with version U.
 
      In January 2013, the Friends announced new findings about the spar and torpedo system and published a number of photographs of the cleaned and conserved spar.  The most important conclusion was that the torpedo was probably still attached to the spar when it was detonated; the submarine apparently did not back off before the explosion.  Previously, some relatively thin material seen in x-rays on the end of the spar was thought to be lead foil wrapped around the torpedo attachment joint to hold it together.  The soft lead would have easily torn through as the Hunley backed away.  Conservation revealed this was actually copper and probably part of the torpedo casing.  Examination of the photographs reveals more evidence that the spar was attached.
       As illustrated in the figure at right, the torpedo attachment bolt remains fixed to the spar end and the copper sheathing is torn (on both sides of the spar) as if it had been pushed back around the bolt shank.  This could have happened when the torpedo was rammed into the side of the Housatonic , or possibly less likely because the torpedo end of the sheathing is rolled over, as a consequence of the explosion.
     The announcement indicated that a drawing of “Singer’s Torpedo used for blowing up the Housatonic” in the national Archives, which shows a hard mount to the spar set at an approximately 22° angle, may be an accurate depiction of the Hunley configuration.

Schematic view of copper remnent on spar end
Figure showing both sides of the conserved spar end.  The torpedo was attached on the left side.  It's likely this segment was separated from the rest of the spar well after the Hunley sank.


After "Singer Torpedo used for blowing up the Housatonic"
This figure, based on the historic diagram referenced by the Friends, shows how the torpedo may have looked attached to the spar.

     The torpedo configuration shown, with no spike and with the detonators at the impact point, indicates the intent was explosion on impact.  Confederate Davids had problems with torpedoes not detonating.  This might explain the multiple detonators shown in the original drawing, and hints that the manual line back to the Hunley may have been intended as a final level of redundancy to assure detonation.  Alternatively, the spool and attached crank may have been used to ship the torpedo, although the crank handle seems small for this purpose.

Conclusions
The above data is incomplete but we can draw some preliminary, general conclusions:

  • The apparatus was likely more complex than has generally depicted to date.

  • A system of guy wires or stays may have stabilized the torpedo (I currently doubt this conclusion).

  • There likely was a mechanism to raise and lower the torpedo.

  • The raising/lowering mechanism may have been workable on the water.

Over the years, new information has trickled out, most notably with the publication of H. L. Hunley: Recovery Operations.  I look forward to a similarly detailed report covering the excavation and conservation of the submarine. 

(The Hunley Forum, previously linked here, unfortunately disappeared when Yahoo deleted all Yahoo Group archives.)

 

(Please let me know if I've missed any significant historical sources above.)


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1 Aug 20