The Test Dive

The H.L. Hunley is famous as the first submarine in history to successfully sink an enemy warship. The attack took place off Charleston harbor in February 1864.

Mobilians are always quick to add to anyone who will listen that the vessel was built here, and so it was. But it is doubtful whether many locals realize that the submarine’s sea trials took place in the Mobile River, roughly where GulfQuest and the Alabama Cruise Terminal stand today. Those trials were witnessed by hundreds and helped convince the Confederate high command that the vessel had military merit.

The Hunley was the brainchild of three New Orleanians – Horace Hunley, a 38-year-old lawyer and sugar broker; James McClintock, a 32-year-old engineer, machine shop owner and former riverboat pilot; and Baxter Watson, McClintock’s partner, about whom little is known. The trio came to Mobile after the fall of the Crescent City and joined forces with Thomas Park and Thomas Lyons, who had a first-class machine shop, complete with forges, hoists, pulleys, tools, open-sided work sheds and a large workforce. Among the latter was a British-born engineer named William Alexander, who took an especial interest in the project.

After one failed attempt with an earlier vessel known as the American Diver (which sank off Fort Morgan in heavy seas), the partners pushed on undaunted. Throughout the spring of 1863, parts for their new vessel accumulated under the sheds. Conscious of prying eyes, the men decided to move the construction phase into the Seamen’s Bethel, which was located eight blocks south on Church Street and only three blocks from the river. Built in 1860, this was an elegant brick church with Gothic windows and doors, bracketed eaves and a modest steeple. (It was relocated to the University of South Alabama in 1968.) Even in the bethel, though, security was somewhat lax. Much later, an elderly Mobilian recalled watching the construction and playing “about the boat.” A rebel deserter told Union officials that he had seen the vessel “in all stages of construction.” If anything, then, the new venture was an open secret.

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William Alexander subsequently wrote a detailed description of the submarine’s construction. His memories have long been a standard reference, but after the Hunley was raised in 2000 and carefully examined, certain inaccuracies in his account became evident, understandable given that he was remembering events that had taken place years earlier.

According to Alexander’s record, a cylindrical boiler was cut in two and then expanded with the addition of two 12-inch-wide longitudinal strips. He even produced a drawing, which showed a 30-foot-long, straight-sided tube with pointed ends, crewed by nine men. In reality, as quickly became evident after the Hunley was raised, the submarine was anything but a slapdash contraption. Several people commented that when viewed bow-on or from above, the vessel looked like a porpoise, with gently tapering ends. Indeed, during the boat’s construction the partners began calling it the Fish Boat (only after its transfer to Charleston was it known as the Hunley).

Not surprisingly, this elegant appearance was not the result of a repurposed old boiler. Modern analysis shows the Fish Boat to have been beautifully designed and fabricated, with wrought iron plates meeting together and affixed to a metal frame. The outside rivet heads were hammered flush to reduce drag, and the actual length was 40 feet. The craft was crewed by eight men rather than nine.

The exhumed vessel sits in Charleston. Aspects of the ship's engineering, such as the positioning of the crankshaft and interior lighting system, have intrigued modern engineers. 

Photo courtesy of Friendsof the Hunley

Other details Alexander got right, such as the rudder, ballast tanks, iron castings fitted to the keel that could be released to lighten the boat in an emergency, dive planes, depth gauge, compass and two conning towers with hatchways sealed by rubber gaskets. But once modern researchers had cleaned out the Hunley and studied it further, they were even more impressed by the vessel’s engineering.

To begin with, the crankshaft didn’t run down the center of the boat, as Alexander had indicated in his drawing, but rather off-center. This required the men to hunch over as they turned it and nicely balanced their center of gravity, dispensing with the need for heavy counterweights on the opposite side. And while the men’s position was uncomfortable – one recent writer called the boat’s interior “an ergonomic nightmare” – their labors were enhanced by a set of differential gears that multiplied and smoothed their force. Underway, the Fish Boat could manage four knots, a slow but workable speed. Small glass deadlights ran along the top of the vessel to help illuminate the interior, and the forward conning tower had larger glass portholes that enabled the pilot to steer visually when conditions allowed.

Once submerged, a candle provided minimal light, and its flame also served to alert the crew to low oxygen levels. Lastly, to help the deadlights and the meager candle, the interior was painted white. In whole, the Fish Boat represented a state-of-the-art submarine for its day. Given the right conditions and a properly drilled crew, there was every reason to expect this vessel to make history.

Come July of 1863, it was finally time to launch the submarine and put it through its paces. In contrast to the American Diver, which appears to have been tested mostly in Mobile Bay, the Fish Boat was first operated in the Mobile River downtown. This was a sagacious choice for several reasons – the river was deeper than the Bay, more protected and less prone to heavy chop, which had done in the earlier sub. Getting the vessel out of the bethel presented a minor difficulty when workmen had to cut away some of the interior columns to make room. But once they did, what had been an open secret became public knowledge.

The trim Fish Boat emerged and, as one man later recalled, “was placed upon a wagon and taken to the slip at the foot of Theatre Street where she was launched into the Mobile River.” People thronged the wharves that July as the Fish Boat cavorted about the stream, diving, surfacing and proceeding from point to point.

At last, on July 31, the vessel’s full range was demonstrated for a gaggle of Confederate brass that included Adm. Franklin Buchanan, who had authority over local waterways. The exhibition took place, just as the initial launch had, off the Theatre Street wharf. The crew clambered into the vessel through the tight hatchways one at a time.

Inside, they took their places along the bench as the pilot stood in the bow and checked his compass. With the officers and a large public watching, the Fish Boat cast off and, towing a live torpedo at the end of a 200-foot tether, steered toward a coal flat anchored mid-river. The vessel’s interior must have been infernally hot, the men laboring in shirtsleeves. Just offshore, the pilot depressed the diving planes, and the vessel disappeared. He then lit a candle as the men turned the crank, and the Fish Boat glided down into the aquamarine murk.

At 20 feet, the submarine leveled and passed under the flatboat. The men continued cranking until the torpedo hit the coal flat, and a terrific explosion confirmed their success. No doubt there were lusty cheers onshore, but aboard the cramped vessel, with its sweating iron walls and close atmosphere, the men were rocked by the concussion and thrown off rhythm. They quickly resumed cranking, however, and soon the Fish Boat broke the surface beyond the flat’s smoking remains.

Exhausted, overheated and panting for breath, the crew threw open the hatches to raucous celebration from the dazzled witnesses, Buchanan not least among them. Convinced now that the submarine indeed had military utility, he wrote to the commander of naval forces at Charleston and offered him the boat. “To judge from the experiment of yesterday, ” the admiral declared, “I am fully satisfied it can be used successfully in blowing up one or more of the enemy’s ironclads in your harbor.” 

Thus, during the second week of August, the Fish Boat was hoisted out of the river, placed aboard two railroad flatcars and covered with a heavy tarp. The army lieutenant in charge of getting it loaded predicted a brilliant future: “It will become, in a very short time, one of the great celebrities in the art of defense and attack on floating objects.” And so it did, though not without first killing several brave crews that included Horace Hunley and Thomas Park among them. Naval warfare was forever revolutionized, however, and it all began here in the Port City 150 years ago. 

John S. Sledge is writing a history of the Mobile River. 

text by John S. Sledge

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