Hunley Archaeology

I included a speculative frame stiffener in the above renderings. A Post and Courier photo shows a stiffening ring an inch or two forward of the aft edge of the opening in the forward ballast tank. There appears to be one in the same position in the aft tank.
There is a small possibility that the crew tossed objects into the tanks over the bulkheads or that the builders left a tool or two behind. The expectation was that only more ballast weights will be found (but see below), but the sediment layers may provide further clues to the loss of the submarine.

The graphic above shows the approximate areas of remaining fill in dark gray. The current hull openings are shown cross-hatched. My guess at the extent of the first two weeks of excavation is shown in lighter gray. In the forward tank excavation may have reached further back toward the cabin than I've shown.

Week 1
The Hunley team spent the first week of the final excavation phase preparing for removal of an aft ballast tank quarter panel and excavating the area exposed by the earlier removal of a forward quarter panel. In lo-res web cam views a smooth, blue-black surface appeared when the concretion was removed form the aft panel area and began to look rusty by the second day. I noticed a similar color when I visited the lab prior to excavation and when the first panels were removed. I still don't know if this is the natural color of the bare iron or a preservative coating.
In addition to the expected iron ballast bars, the archaeologists found a small wood cask near the bottom of the forward tank. Initial speculation about the cask, which is partially filled with different sediment from the tank, offered several possibilities:

Float to indicate tank depth
Chamber pot
Container of some liquid

Just small enough to pass over the top of the bulkhead, the cask might have been dropped in by accident. It's also possible it was left behind during construction. If it were a float, it seems to me it would have been found higher up in the tank and would contain similar sediment to the tank. It's not likely a cask of hooch would have been placed in the tank, but it might have been wedged at the top of the bulkhead and fallen in. We could better speculate on the chamber pot possibility if we knew a little more about the cask. If a chamber pot were used, it's possible it was dumped out in the tank and could have been accidentally dropped. It seems to me less likely that this would have been a task for the commander, though, unless he had his own. Of course the aft bulkhead is less accessible because of the propulsion and other machinery located there. If the cask were dropped in the tank, there's no reason to suppose this occurred on the final mission. Once in there it would be difficult to retrieve.

Week 2
The aft ballast tank quarter-panel was removed Tuesday of the second week. A fuzzy web cam snapshot showed probably 16 rivet holes along the panel's length and perhaps twelve along one vertical edge. There appeared to be a structural feature on the forward side of the new opening, probably a stiffening ring, similar to that seen in the forward tank opening. The aft portion of the area appeared to be have been already excavated through the large opening on the starboard side. Excavation through the new opening proceeded quickly in neat stages, following standard archaeological practice. In the later stages, the steering rod was clearly visible running through the upper part of the tank. At the end of the week, the slightly different perspective afforded by filling the preservation tank revealed the propeller shaft as well.

Week 3
There were no announcements this week, so progress can be measured only by the very limited oversight provided by the web cams. There was activity at both tank openings. The interior cam showed the forward tank excavation had reached the cabin by Tuesday. Excavation in the aft tank was certainly proceeding toward the cabin.

Week 4
Again, no announcements from the Friends. Activity in the forward tank, as gauged by the web cam view, appears to have completed by midweek. Conservation hoses and pipes, other extraneous equipment, and water puddled on the cabin floor were removed, probably for detailed photography, including what seemed to be a a flythrough video when a camera was moved along a guy wire run the length of the cabin. Even the interior web cam was dismounted, providing a momentary and murky view aft showing the opening into the tank. The rectangular shape where steering linkage passes over the bulkhead was clearly outlined by the light from the tank. On Friday one of the team was in the tank working forward. Activity ceased early perhaps indicating excavation is complete.

Later
At the end of week 7 the Friends finally announced the completion of the tank excavation. They revealed that the cask found in the forward tank the first week probably contained a caulking compound and that a chisel-shaped tool found nearby was probably used with it. They reported that a coil of rope was found in the aft tank. They also reported activity in the crew cabin to remove previously unidentified items including some small tools.
The announcement included some speculation that the cabin tools might indicate repair activity during the last hours of the Hunley. A report in the Post and Courier included the cask and iron in this complement of tools. My own belief that artifacts found in the tanks were left there during construction or maintenance that took place in port. The initial report of the removal of the forward tank plate indicated the plate showed signs of repair. The location of the cask far forward in the tank weighs against it's somehow being stored there or dropped there that night. The coil of rope in the aft tank is also problematic. I doubt rope would be stored in the tank and the considerable amount of machinery in the cabin near the aft bulkhead makes it improbable that it drifted or was dropped there during the last voyage, although losing it there during maintenance or similar activities is always a possibility. My own thought is that it was used as sealing material during construction.
The Post and Courier report revealed a pipe between the two ballast tanks. There was no mention of how this was accomplished or connection with the pumps or valves. As always a photo would be appreciated but these are rare these days.

Finally, the next phase of activities was announced. After additional laser mapping and x-ray documentation of the interior, the internal mechanics will be removed for separate conservation. The bench, crank, pumps, and ballast ingots were specifically listed in the Post and Courier report.

From the beginning of this project archaeology and conservation have been applied together. The archaeologists excavated during the day. Every night the Hunley was kept in a preserving underwater environment. As features were exposed, the conservators came in to treat and protect them. After the removal of the sediment, conservation has become the dominant process, but archaeological recording techniques are still applied as concretion is removed since artifacts and features are exposed during the removal. In January 2005 the Friends announced the removal of the crew's bench. At the time of the announcement the two forward sections had already been removed and work was proceeding on the final section. They revealed the total length as 17.85 feet, clearly converted from the metric used for documentation throughout the project, and described the forward section as six and a half feet long. My reconstruction had that section correct but my total length was about 20 inches too short. The report mentions the aft section is "mounted within submarine's aft pump mechanisms" so it is likely I have that one too short. I had used a ¾-inch thickness rather than the announced three centimeters, a rather careless mistake on my part. Standard wood measurements (2x4, 1x12, etc.) have decreased in actual size over the years, but I recall that the studs in my not so very old house in Connecticut measured a full two by thee inches. The report also described the the bench as still 50% covered in lead-based paint, a fact that has been obvious in the numerous bench photos previously released. Removal of the bench will give the conservators better access to the heavy concretion still under the bench especially in the aft part of the cabin. A number of artifacts remain in the concretion. In mid-February 2005 the scientists showed the removed bench to the press and revealed it is "heavy ... conifer, pine-related wood" and had been painted several times with a white, oil-based paint. This supports my reconstruction concept of a white interior. The scientists stated that the condition of the bench indicated it had been in an oxygen-free environment and suggested that the cabin did not fill with water early on. Associated Press photos showed what appeared to be each end of the center section. The aft end showed a long piece split off the back of the bench that had been apparent in earlier published material. The forward end revealed three metal fasteners - probably nuts - embedded in the wood a half-inch or less from the end. The Post and Courier revealed the presence of a joining block here. Additional low resolution photos published later in the Friends' Blue Light newsletter don't provide much additional information, but show that concretion was removed from the stiffener rings where they pass through notches in the bench. Earlier photos show this concretion spreading out some over the wood. I considered and ultimately rejected this as evidence of bracket locations. The latest photos confirm my identification of the center section above, but offer no new clues about the mounting mechanics.
By mid-April 2005 the depth gauge had been removed. The Friends reported that the glass tube must have broken during the last mission or shortly thereafter since a pool of mercury was found on the cabin floor beneath the sediment. Although the dangers of mercury were not as widely understood then as they are today, it's unlikely that the puddle would have been left there if the break had occurred earlier. The apparatus was reported to be three feet high and mounted on the port side of the cabin at Dixon's position. We've known since the Smithsonian presentation that the gauge inlet is on the port side just above the ballast tank valve inlet but mounting the gauge along the side seemed strange to me. The hull side is curved and the apparatus would need to be curved or bent to be out of the way, especially since the dive plane control lever moves through that area. At the time I speculated that the report included a misunderstanding and that only the inlet was on the port side. Dixon's shelf has a cutout in its forward edge next to the tank bulkhead and photos show some vertical lines in the bulkhead above and below the shelf. Subsequent publication of an x-ray of the gauge and close examination of earlier photos verified my speculation that this was a better position for the gauge. (Read more about this on my reconstruction page.) The shelf must have been removed first to permit removal of the gauge. The speculative graphic at right shows the gauge approximately as it looked upon removal. The concretion is probably more extensive than I've shown and the inlet tube may extend further to the left.
The gauge announcement was made while I was pondering the possible effects of the torpedo detonation, probably a pressure surge on the order of 950 psi, on the Hunley leading to a Eureka! moment. It appears from what we have heard to date that the hull suffered little damage from the explosion, but the thin glass tubing, less than ¼" diameter, subjected to the same pressure as outside the hull may have burst.
The first deadlight was exposed in June in the center panel, the first removed back in 2001. The news reports used the term to refer to the iron covers over the glass, whereas earlier reports had referred to glass ports themselves. The nautical term can apply to either. An interesting thing to me was the great difference between the amorphous blob of concretion that concealed the very cleanly defined shape of the cover hardware below. I had noticed this before where some of the rivets around the forward hatch had been cleaned, but the published side-by-side photo of two deadlights, one cleaned, one concreted, brought the message home. Many secrets of the Hunley construction will be revealed as more concretion is removed. Several views of the sub have provided clues of what we can expect as the process continues. The joint between the hatch covers and coamings is now wrapped, hinting that there has been activity here. I'm afraid, as Robert Neyland stated several years ago, that the Hunley will need to be dismantled to separate the different kinds of iron of its components. A week later, the Friends announced the discovery of an oddly marked copper plate on the floor of Dixon's station. Traces of zinc on the plate, a piece of copper wire found nearby, and what was described as a spool of wire hanging in the forward ballast tank led to speculation that this might be part of an electrical detonation system for the torpedo. The spool is actually a loose coil that was hanging in the tank on the inlet pipe. A photo taken in 2003 during the forward tank excavation but just published shows a coil of approximately one-foot loops. Clemson University experts are studying the plate. I'll wait for the their report but I'm initially skeptical of the interpretation. I think that battery technology of the time required a container with a liquid electrolyte. Unless the remains of such a container are found, I think it's more likely that Brian Hicks' suggestion that wire was used for the mechanical trigger lanyard is correct. (See my reconstruction page for a different speculative thought about the plate.) The initial assessment by the Clemson scientists, published in the fall issue of Blue Light (Volume 17, October 2005), validated my battery technology comment above. The same issue includes a sidebar expanding on Brain Hicks' lanyard speculation. To end 2005 the Friends announced removal of the glass from the forward tower viewports. No official photo was released, but Brian Hicks' Post and Courier article included several. The clearly pictured port-side viewport closely matches details in an x-ray displayed in the Warren Lasch Conservation center. Externally, the viewport has an outside diameter of nearly four inches with an opening of about 2 and one-third inches. The port is affixed to the tower with four rivets or bolts. In May 2006 The Blue Light reported the discovery of rubber disks blacking out ports in the forward hatch tower. The plugs had string lanyards for easy removal or to keep them from being misplaced when not in the ports. Some of these were found in place, but at least one was discovered on the floor of the submarine. The report is incomplete providing a count only for the forward hatch, but these must have been standard for both the forward and aft hatches. To date no photos have been published of the porthole work on the aft hatch. The article also mentions "concreted rods" on the floor of Dixon's station that may be "remnants" of the forward hatch latching mechanism. In Jul 2006 the Friends announced the discovery of parts of the forward hatch latch mechanism apparently stored on the floor on the left side of Dixon's station (as reported by Brian Hicks in the Post and Courier). The mechanism appears similar to the latched aft hatch mechanism, a flat, rectangular bar with a hole threaded on a rod attached to the hatch lid. The various reports are not consistent, but we can infer from these and earlier reporting (see above) that two major parts of the forward latch were found behind the rudder linkage and ballast tank interconnect pipe. As always in archaeology, where artifacts are found is as important as the artifacts themselves. Since the Hunley lay on the bottom listed about 45 degrees to starboard and the linkage and pipe run on the port side, it is unlikely that the latch could have fallen to that position, for example, as a result of the later event that made a hole in the hatch coaming. The dive plane lever with its large counterweight is above the position, making it unlikely the mechanism fell there even if the sub was upright. The most likely implication is that Dixon stowed the latch there. At about the same time, the monthly member update announced the discovery of another port in the aft hatch tower. Unfortunately, no location or new total number was mentioned. Assuming there were earlier thought to be three - one on each side and one in the hatch cover - the new one may face aft, providing a view toward the original towed torpedo. A port facing forward is less likely because hinge mounts. Conservators removed the rear hatch cover in mid-September 2006. Removal was necessary because the cover deadlight glass could not be removed from outside and the latch mechanism prevented access from inside the sub. Upon removal the conservators found what may be a small valve in the lid about halfway between the forward edge and the deadlight. Removal of the hatch cover exposed the top of the hatch tower, revealing the actual thickness of the original metal. Very nice photos published in the Charleston Post and Courier show the actual thickness to be a very thin 1 to 2 centimeters. The interior concretion is twice as thick, helping to explain the lack of visible detail. The concreted latch mechanism is visible in two photos. A narrow vertical rod with a knob-like tip rises near-center in the hatch tower from a larger crossbar fastened side-to-side below the tower. The smaller hatch-top photo reveals a similar knob near the center of the lid. What may be the end of the suspected valve handle is just discernable. Over the years there has been much speculation about what caused the large hole in the Hunley’s aft ballast tank. In mid-November 2006 Brian Hicks reported in the Post and Courier that this and other damage could have been caused by strong water currents sandblasting the iron. The starboard hinge on the aft hatch cover is noticeably worn as are many of the view port mounting rings. The scientists believe it’s possible that even the now-familiar curve of the Hunley’s bow is a result of this sand-laden current scouring. The damage is mostly on the starboard side, probably because of the extreme list to this side. A swift current moving through here could have been accelerated by the Venturi effect and whipped up additional sand. Current scouring is natural around wrecks, which change the flow over the sea bottom. Typically a bowl is formed in the sand under the wreck and it slowly sinks until it is buried, at which point the original equilibrium is restored. According to the Hunley and Housatonic site assessments, both of which provide considerable analysis of the effect of currents in the area, the submarine was completely covered in about 25 years. Divers working on the Hunley site attest to the strong normal currents in the area and it isn’t a big leap to imagine the effect of a sand-laden, Venturi-accelerated current on the iron. The current would not have been uniform, but could vary considerably within just a few inches. Places subject to high current would experience more sand erosion than other areas. The hatch hinge, projecting out into the current, could experience very heavy erosion, as could places near the sea bottom. In time the hull plates subject to the highest sand scouring could have been worn so thin that minimal corrosion could perforate them. Areas subject to very high scouring could have been perforated by the current alone. A photo of the hatch lid published in Blue Light number 22 (Winter 2006) shows considerable damage to the starboard side of the hatch lid rim. Unlike the smooth distortion of the hinge, the damaged surfaces on the rim are jagged, looking more like a fracture than wear. This could be a consequence of erosion and deterioration or could be the result of some kind of impact. In January 2007 conservators opened (rather than removed) the forward hatch. The intent was to expose the rubber seal in the lid so it could be removed. This must be done before the chemical corrosion treatment of the metal can begin. However, some of the concretion around the hole in the forward hatch tower is attached to the lid and covers the seal. It is possible that the damage occurred any time from the night of the submarine's loss to many years later. The hole could be the result of a violent impact or the result of continuous wear in the sand-laden current. All the concretion around the hole needs to be carefully analyzed to place this damage in the Hunley timeline. Removal of the seal will be delayed until this study is complete. In April 2007 the Friends finally published a photograph showing the forward-looking ports. These are located nearly at the top of the hatch tower, not low down like the side ports. At the end of August 2007, the Friends of the Hunley announced the discovery of several small pieces of cast iron on the cabin floor beneath the forward hatch tower. One of these pieces is curved and, as demonstrated on the History Channel program Digging for the Truth in September, is close to the curvature of the port glass of the starboard-side view port. This raises the possibility that it is part of the missing port-side view port. Soon after this, during the member appreciation events, the Friends publicized earlier speculation that the distinctive curve of the bow is a result of sand scouring and that the original shape was straight up and down. I've updated my plans for this, although all the other images still show the curved shape. In January 2008 conservators removed the aft pump from the Hunley. This is part of the continuing process of separating materials that would be damaged by the chemical treatment that will stabilize and preserve the iron hull. To gain access to the bolts that attached the pump to the hull, in December they had removed the approximately 500-pound aft-most keel weight. This is one of four that were permanently attached as opposed to three that were designed to be dropped with releases in the cabin. Brian Hicks revealed that the top of the weight was curved fit snuggly to the hull but "there was a little wood between the block and the sub". Photos of the pump reveal a confusingly complicated mechanism, weighing on the order of 150 pounds, with similarities to the forward pump. There is what appears to be a large valve attached, with a pipe extending forward a foot or more before making a right angle turn into the cabin side. The position of what appears to be the valve handle leads me to believe it is in the open position. This likely outlet line was fastened to the hull by a square plate. Other parts attached to the removed mechanism may be other valve assemblies. The Friends plan to use x-rays to determine valve positions. Earlier photos of the aft section showed what was apparently the pump handle. This feature does not appear in more recent photos and it was not attached to the pump at its removal. (See the tanks pop-up on the reconstruction page for some speculation on the pump valve system based on earlier reports.) Conservators removed the forward pump from the Hunley in late May 2008. As with the aft pump it was first necessary to remove the fore-most ballast block to gain access to the four lower attachment bolts. A photo released by the Friends of the Hunley shows how closely the block is fit to the hull. There is a rectangular groove running half way down the top of the block to accommodate the joining strip on the bottom of the tapered portion of the hull. This pump was attached to a hull stiffener ring by a bracket at the top. The pump handle is still attached to the pump. The pivot end of the handle had to be unbolted from another bracket on the stiffener to permit removal. As with the aft pump, the outlet pipe ran forward to a right angle bend and attached to the hull by four additional bolts or rivets. There appears to be a valve in this pipe at the pump end, with its control handle on the bottom. It’s likely that this pipe supported Lt. Dixon’s seat, so placing the handle on the bottom kept it out of the way, but accessible. To me the valve appears to be closed. What may be the open end of the inlet pipe is visible at the bottom attachment plate in a photo published in the Charleston Post and Courier. A curious Y- or C-shaped mechanical feature straddles the lower portion of the pump in the same photo. The top part of this feature is visible in much earlier photos of the pump area. In early 2015 the Friends released photos and videos showing the Hunley's exterior completely cleaned of concretion, revealing new details of its construction. The first thing I noticed is that seams on the lower hull in the tapered sections of the hull don't match up with those on the upper hull, evidence of the use of existing metal plating in the Hunley's construction. The photos I've seen don't show the central hull in sufficient detail, but I suspect the seams there match. Some interior photos showing the rivet plates support this. It appears that the conservators removed anything under the concretion that was not physically attached to the hull. I've not seen anything describing what caused many of the bumps. In the past, we've tried to interpret these as equipment but they could be natural or otherwise extraneous. Pending further information anything no longer on the hull must be considered unknown. The new photos do confirm some details in Chapman's painting, but one prominent feature he shows on the port side just aft of the aft hatch tower appears in the photos to be two much less noticeable bolts. My initial guess, pending further investigation is that these were associated with the aft pump installation. I've updated my plan drawings, available on my reconstruction page, to reflect what new information I've been able to extract from the photos. The Fall 2016 Blue Light (Vol. 48) includes information about the depth gauge as well as post-conservation photos. The four-page article reports a wood plug "jammed into" the glass coupling. This could only be done if the glass tube, indicated to be some 30 inches long, was removed. The article speculates plug was intended to disable the gauge, but this seems unlikely to me because the remains of the glass tube as well as some mercury was found on the floor of Dixon's station. To me it's more likely that the glass broke or came loose and Dixon used a piece of wood to staunch the flow of mercury, perhaps fearing water could follow. As the glass remained in the cabin, we might speculate this happened during the final mission, but it's not certain that the cabin would have be tidied between missions, removing the likely broken glass.

	rchaeology is a science with a set of standard methods and techniques and an art that draws on the experience and knowledge of the archaeologist to interpret what the process reveals. It requires careful and meticulous recording of the context of finds because in its most usual form excavation is destructive.
Understanding Archaeology
It will help to summarize the archaeological process before going on to the Hunley excavation particulars. I can't overemphasize the importance of accurate recording of context for all artifacts and features discovered. Every project is a little different in detail but all do this one way or another. I'm not an archaeologist, but for well over a decade I've participated in and contributed to numerous archaeological projects. I’ve drawn on this more than six months of hands-on field experience to provide the background and explanation on this page. Excavation proceeds at a preplanned pace. That is, fill is removed a little at a time over a predefined area. At any time, no place within that area will have been excavated much deeper than any other. When an artifact (or feature) is discovered, it is not removed immediately, but the fill in the entire area around it is lowered to free it. For some projects only major finds are recorded individually, but it’s likely that everything was treated this way on the Hunley. The find is assigned an identification code that will be used to track all information about the item in the project database. The information includes the exact X, Y, and Z position of the item, including what part of the item the coordinates refer to, the item's size, and if relevant, its orientation. A narrative description is written, including condition, distinguishing details, and identification if known. Before the item is removed from context photographs and possibly drawings are made. The context itself is described, including the archaeological layer in which the item was found - this layer has its own description in the database. When the artifact is removed, it is tagged with its identification code. Often it isn't possible or convenient to excavate something in situ. In this case what we can think of as a super-object is defined. On the Hunley, these were called "block lifts". The block lift is treated as just another artifact and documented in the same way. Later on the block lift itself is mini-excavated using the same process described above. Since the context of the lift was recorded, the context of everything found in the lift can be transferred back to the overall context. After removal, artifacts are cleaned to aide in further identification and the description is augmented as appropriate. Cleaning might be as simple as washing sediment away or as complex as applying special conservation techniques. On the Hunley project, block lifts and often other items were x-rayed. Since many artifacts were heavily concreted or contained other artifacts, this aided identification or guided further mini-excavation. Like all science the results of an important archaeological project are published formally for peer review of the conclusions. Proper technique and complete documentation are essential for evaluation and acceptance of the results.

	The view at left approximates an underwater photo published by the Post and Courier in June 2001. It shows a possible control rod or air pipe under the bench, but not some of the large featureless concretion masses also visible in the photo. The sediment remaining on the floor is also speculative.

After a considerable hiatus a fifth hull plate was removed in July 2003. A quarter panel was removed from the forward tank for conservation study and to provide access to the tank for sediment excavation. The plate is part of a panel that was previously though to be a single piece. The only other access, a small hole on the starboard side and the opening over the cabin bulkhead, is insufficient for this task.
	A similar situation exists in the aft tank. Although there is a large hole on the starboard side of the tank, it is far aft, limiting access to the remaining sediment. Access over the bulkhead is limited by the steering linkage, the propeller flywheel, and the other mechanisms in that location.