Interesting article, but also strangely quite superficial, and poorly supported claims. The item noted to be attached to the spar, thus far has not been completely determined to have been part of the torpedo itself. It very well could have been an link attachment item.
There is no other evidence found thus far that would indicate that the Hunley was lost in the torpedo blast. Yet lots of other evidence that indicate that it wasnt.
The article states that they were only 20 feet away when the torpedo blew. However multiple eye witnesses aboard the Housatonic reported the vessel was in the process of rapidly pulling away and was about 100 feet away when the blast occured. There was no obvious damage to the hull of the Hunley that would suggest any real blast damage, nor indication that the effects of same immediately sank it, as the article is suggesting. The Hunley is not still sitting in a chuck of sand, the interior has been excavated, as well as majority of the exterior. It has been x-rays tons of times to see exactly where structures and supports are located within before hand. No obvious critical structural hull damage has been found that would be suggestive of blast damage.
All the crew members were found at their respective stations within. Not deranged, tossed about into piles as such a close in shock blast would typically cause, or a flooding panic. The Housatonic hit the bottom reportedly in less than five minutes. If the Hunley were indeed significantly damaged or sunk by the inital blast one would normally expect to find her wreckage in close quarters to that of the Housatonic. However the Hunley was found about a 100 yards further away.
It had long been suspected that the musketry fire from the deck of the Housatonic may have done enough damage to cause her to sink. A feasible synopsis, but only one small damaged area was found on the Hunley that might have been caused by such, one small hole on one of the conning towers. Sufficient to sink it?, might have been a contributing factor, maybe not. If she was on the surface after the attack as thought, it shouldnt have, it would have then been above water line.
What is recorded is that the Hunley was suspose to give a "signal" to the station at Battery Marshall, when it was coming back in. The reported signal was reported to have been received about an hour after the attack. Some accounts arent completely clear what the signal actually was. Some say a signal via a light, some accounts say a blue(ish) light of some description.
The Hunley went out with the outgoing tide on the attack. It was also known that they would probably have had to wait till the tide changed before they could actually get back in. They went out, the attack was made, and hour later the signal was given, then wait out the tide to be able to get back in. But then she never returned.
Another more recent theory to the cause......
Since they had to wait out the tide to come back in, and try to prevent being pushed to far out with the current/tide. They were most likely sitting on the surface and decided to toss out an anchor to help hold against the current till the tide changed, and being pushed out to sea.
The Hunley wasnt found closer to shore from the Housatonic, but actually further away, suggesting they were indeed being pushed out with the tide. A small anchor carried inside and tossed out the open hatch teathering the vessel in place. An small period anchor was found about 25 feet or so from the vessel with the eyelet pointing back to where the Hunley layed. If this was the Hunleys anchor and they tried to use it, it could have been the accidental cause of the sinking.
In a typical surface boat using an anchor it will generally hold the boat in place. Using the same type of anchor in a half submerged sub of that small size being actively pulled by the current would have had a much different effect. Since they hadnt had a chance previously to try and use an anchor with this vessel, It was doubtful they knew what to really expect. If they sat there with the open hatch, and that anchor grabbed, it would have immediately tipped the vessel down and yanked it underwater very quickly. The crew wouldnt have ever had a chance to even react, it would be just dunked under in seconds and gone.
I have a close friend that worked on the Hunley project, in both the recovery and much of the earlier excavation/conservation work on it. He also wrote the book on the Hunley. That project was his sole passion, long before it was even found, so we had tons of data over many years of study to look over. We frequently sit around talking about all this stuff. He also tested this same dunking theory out on his own small research sub using an anchor in similar fashion for curiousity, and it reacted exactly as predicted... dunked it... Same as would have happened to the Hunley.
The Hunley was found intact at a different location from the Housatonic, no obvious or significant hull damage that would suggest blast or structure failure. Crew all found in their respective stations. This particular anchor theory is probably the most feasible and credible theory, that actually has supportive evidence, about the possible loss of the Hunley to date that Ive encountered out there.