Watched a special on the Histovery channel. Seems to me, although there was no mention of it, that the reason for the repeated sinkings was simple hydro pressure. The Hunley had hand operated pumps to pump out the ballast tanks. Most likely, at 20-30' of depth, the water pressure outside the hull was too high for the pumps to operate. Thus, the boat submerges, and below a certain depth, just keeps going until it hits bottom. JR Dweller in the cellar
Just $.02 here from an ex commercial diver.
For every 33' you descend in salt water, the pressure increases 14.7 psi. Hence, 14.7/33=.445 #/ft. at twenty feet, it would have been an additional
10#, so not a lot. At 30, it would have been an additional 13.3#, not a lot either. But, not knowing the specifications of those pumps, it would be hard to tell.Either way, though, your idea does hold water. (Did I really say that?) The pressure would have been increasing predictably and there would have been a point where the pumps would not have been able to push any water out at all. The important thing is, though, that upon leaving surface, the pumps would start losing efficiency.
In diving, there is a very crucial balance called neutral bouyancy. An object underwater is neutrally bouyant if it is neither rising or falling. The new diving systems have pushbutton technology that adds just the right amount of pressure to the flotation bladder to achieve this within one second. It is obvious that the Hunley did not have this. They would have not been able to compensate quickly enough, and once it started towards the bottom, it goes faster and faster. Conversely, upon rising in the water, if pressure is not let off, the air expands, and you shoot to the surface. Particularly in the last 33 feet when the volume of air doubles as the pressure is reduced by 50%.
I would like to see a Navy analysis of these things once they do research on these things: volume of the vessel, weight, displacement, pump capacity, etc. I am unsure if there were any ballas tanks at all, or if it had the ability to compress air and store it. Once you dump some air to go down, it is gone, and you have to have a compressed supply if you want to surface unless you have power. I am sure it was just marginal operationally, but it DID do its job at least once to the astonishment of the enemy.
Altogether a fascinating story. My favorite part is them finding the captain's inscribed gold coin. It had been mentioned historically previous to that, I believe it was a presentation piece.
I really got jazzed about watching them dive, with the Kirby-Morgan helmets, the decompression chambers, and the quack-quack talk on the radio. I had the pleasure of doing that six years of my younger life, and it was HIGH adventure on the high seas.
steve
Clive Cussler did a ton of research on the Hunley (it was his NUMA group that found it) and the most likely cause for the repeated sinkings was asphyxiation of the crew. A second possiblity is because the ballast tanks were open at the top, they flooded the vessel, which appearently had no bilge pump.
Can you imagine being in the dark (illumination was by candle), tired by lack of oxygen, trying to save a sinking vessel. BRRRR.
Gives me the willies.
-Carl
The Hunley wasn't flooded in the sinkings. The description of the crew as "blackened corpses" indicates decomposition in air. JR Dweller in the cellar
Carl Byrns wrote:
Greetings:
It's not so much asphyxiation that initially incapacitates in these circumstances, but rather, carbon dioxide buildup. Although asphyxiation may have been cause of death, the crew would have been out of their minds with the stress of elevated CO2.... unless the CO2 was scrubbed, in which case the crew would have simply gone to sleep. Very insidious onset.
Regards, Jim Brown
I think that vessel went through about three or four full crews.
My favorite though was Bushnell's Turtle.
Jim
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Maiden voyage: Lt. John Payne causes boat to dive while hatch is jammed open with a rope. Boat floods. Two survivors, five dead.
Second voyage: Horace Hunley himself miscalculates angle of descent and allows forward ballast tank to overflow. Sub hits bottom, tank overflows. Hunley forgets to close valve. Sub floods drowning crew of eight.
Third voyage: During a test to find out how long the crew can last without fresh air (2 hours, 35 minutes) the aft pump fails. Tired and nearly unconscious, William Alexander disassembles pump, finds and removes a seaweed clog, and reassembles pump. In pitch dark.
Fourth voyage: The Hunley sucessfully attaches and detonates a torpedo, sinking the Union sloop-of-war Housatonic. What happened next is theory. It's believed that the Hunley was accidentally rammed by the Union warship Canandaigua, whch was hurrying to rescue Housatonic's crew.
When the Hunley was recovered, she was full of silt and water. The Hunley killed 22 of her own crew, was sunk three times, and raised and returned to service twice.
-Carl
There must be a second episode that I haven't seen then. The first one ends with them taking the Hunley back to dock. I'll watch for it again.
My favorite part of the first episode was when, after many years of searching, the captain calls the financial backer (forget the names) and says he's giving up the search... pause.... because he found it!
Talking about playing with a guys emotions :^).
John
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As best I can remember it:
The captain carried a gold coin for luck. Previously, it had been engraved. It was recovered among the silt inside the submarine. The thing that distinguished it from any other gold coin was the inscription. A dead on match. I can see how archaeologists would get excited when any two pieces of the puzzle come together. But the EXACT coin would be a special case.
Steve
Bushnell's turtle pre-dated that conflict by about a hundred years. I was particulary intruiqued to learn that the nav instruments in that craft were 'glow in the dark' (or were supposed to be, but for an early frost that year) using a bioluminescent fungus. Foxglove, maybe?
Jim
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Actually, the South _was_ known for it's navy- some of the ships became quite famous and the southern ironclads were pretty advanced designs.
The Hunley was the first sub to sucessfully destroy it's target.
-Carl, a damn Yankee
Grrr. The Turtle was *this* close. The damn auger screw came loose from the ship that they screwed the mine to.
Jim
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That is impressive. Really makes history come alive I'd say. I imagine it was almost like being taken back in time to hold it in your hand after hearing about it for a 150 years.
John
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Shouldn't that have been "y'all Yankees", Bob?
that could be "All ya'll", but "You" is perfectly acceptable in this context.
Gunner
"What do you call someone in possesion of all the facts? Paranoid.-William Burroughs
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