On 13 November 1873, one of the most unusual ships in the U.S. Navy—the USS Alarm—was launched at the New York (Brooklyn) Navy Yard. Literally, from stem to stern, there had been nothing like her before or since.
During the 19th century, the world’s navies could not avoid the lingering effects of the Industrial Revolution. Steam power had been introduced and accepted in Navy circles by the onset of the American Civil War. Iron was seeing more use in hulls and, of course, in armor. Given the needs of the internecine conflict, the U.S. Navy focused on immediate concerns, primarily defense (and offense) around inland and coastal waterways, the reduction of brick-and-mortar and earthen redoubts, and the threat of Confederate armored ships. Meanwhile, European navies, concerned with confronting each other, were addressing their own issues. Their focus turned to fully seaworthy designs and gunnery, especially the advantages of breech-loading rifles over muzzleloaders.
The U.S. Navy, while trying to come to grips with nautical evolution in the 1870s, was stuck in the past. The “monitor lobby” still held sway in the service’s thinking despite that ship type’s many disadvantages. Admiral David Dixon Porter did not count himself among the lobby’s number. But that did not put the Civil War hero in the forefront of Navy thinking. He had been impressed by the spar torpedo invented by the Confederacy and was fixated on developing its potential. He also saw the ram as a more viable weapon for better-constructed, lighter, faster, more maneuverable ships. Porter envisioned naval conflict as close-in littoral fighting, whereas the rest of the world was looking toward combat at sea and at ever-increasing ranges.
The admiral’s design for a “cruising torpedo boat” became the test ship for an improved spar torpedo and was among the Navy’s first forays into purely experimental work. The vessel was, however, still a manifestation of the Navy’s littoral-centric philosophy. An 1882 Navy report noted that “for use under any of the conditions of littoral warfare . . . her dimensions and form were peculiarly adapted by her designer for that purpose.”
Porter envisioned a fleet of “modern” light, agile boats, which although lightly armored would have double hulls and watertight compartments. They would carry electrical mechanisms to deploy and trigger their torpedoes, and a XV-inch Dahlgren gun at the bow. While the spar torpedo boats of the Civil War had been virtual suicide craft, the Alarm was designed to be survivable. She had a 24-foot-long ram prow, which contained a steam-operated torpedo deployment mechanism. This projected the spar torpedo forward another 30 feet from the ram’s tip, which put the crew and boat out of danger from the exploding weapon. Provision also was made for two additional torpedoes to be extended 17 feet at an angle to the bow on both sides. To provide stealth, Porter designed her hull—the first U.S. ship with a complete double hull built on transverse frames—to be flooded until the spar deck was just above sea level; her stack could be telescoped to half its standard height and all deck structures were built as low as practicable.
The justification for her design almost seem comical in the light of history. It was intended that she keep her bow onto the enemy at all times, not just for offense but also defense. The vessel’s iron hull, with 1½-inch iron armor at the bow, was cut away forward to accommodate the ram but also to protect the hull from the shock of firing the Dahlgren, which was fixed in a forward-firing-only position. The gun’s muzzle needed to project forward of the hull. Making this more difficult was the need to have the heavy gun and its mounting—at more than 23 tons—placed sufficiently aft to obtain the needed buoyancy for their support. It was noted that this positioning also exposed less of the hull to enemy fire.
Simplistic almost beyond belief, the report touted: “The vessel is thus not only a torpedo boat, but a gunboat, solving the important problem of carrying the maximum gun on the minimum hull, and having a direct fore-and-aft fire with a capability of prompt and accurate aiming in azimuth not obtainable by any other method.”
While the not-so innovative spar torpedo and ram accounted for the Alarm’s unusual bow characteristics, the highly innovative stern accommodated the ship’s desired azimuth capability. For this, the torpedo boat required a steering apparatus that simultaneously would act with great “delicacy” and “great power” when the ship was at rest and be as effective when backing as when going ahead. A rudder is useless when the vessel is at rest and unpredictable when backing. Twin screws were slow in providing directional control and necessary precision. Further, for directional control, to back one screw while advancing the other, required one engine to be stopped, reversed, and reengaged. All this took valuable time.
A substitute was needed “that could propel, steer, back the vessel, turn her upon her vertical axis when in motion or when at rest, and maintain it in position.” Porter’s solution was the Fowler Wheel, an early cycloidal propulsion system based on a four-blade horizontal feathering paddle wheel. The wheel rotated in only one direction, clockwise when viewed from above, with its blades controlled by links to a camshaft. To move forward, all the paddles would be feathered—pointed in the direction of travel—except as they approached the starboard beam position. There the paddles were rotated perpendicularly to the ship, providing forward thrust. Similarly, reverse thrust could be provided immediately by adjusting the cam to allow only the paddle on the port beam to provide thrust. The cam could be adjusted to accommodate any point of the compass, even from a stationary position.
The report used glowing terms to describe the ship’s maneuverability with the Fowler Wheel. The mechanism, however, could not deliver on the promised speed and efficiency. The Alarm was barely able to reach 9½ knots, well short of her 13-knot design speed. The wheel required about three times the power needed by an ordinary screw to achieve the same speed. “[T]his defect was fatal.”
After the Alarm’s first trials following commissioning in 1874, her engines, which had not been properly secured to their bedplates, were so stressed they had broken from their mountings, requiring costly repairs to a virtually brand-new ship. For the next four years she was used for experiments at the Washington and New York Navy Yards, but mostly sat idle until 11 June 1878, when Lieutenant R. M. G. Brown was put in command to salvage what he could from the ship. He immediately began advocating replacing the wheel with a Mallory Steering Screw. Congress released an additional $20,000 for the modification.
The Mallory invention was a complex device that featured two transmissions to change the axis of the propeller shaft rotation not only from horizontal to vertical and back to horizontal, but also allow the screw, mounted on the lower transmission, to rotate 360 degrees on the horizontal plane. This allowed the screw to provide thrust in any direction. The only major modification the Alarm needed was the deepening of her keel aft.
Brown was convinced that with this change, the Alarm design will “be perfected.” The Fowler Wheel was removed and the Mallory system—including a single six-blade, ten-foot diameter screw—was installed. (A later improvement provided twin back-to-back–mounted screws rotating in opposite directions to eliminate torque effects.) Despite his advocacy—and the new motive device—during tests in July 1881, the Alarm’s speed remained far short of what was desired. In addition, the increase to her draft of some 3½ feet erased one of her salient and necessary features.
Although a disappointment—and a naval three-time loser with dead-end technologies of spar torpedo, ram, and cycloidal propulsion—the Alarm conducted a series of experiments at the U.S. Navy Torpedo School at Newport, Rhode Island, but was returned to the New York Navy Yard and placed in ordinary. In 1891–92, she was converted to a gunnery training ship, but the vessel does not appear to have served as such. The Alarm was struck from the Navy list in 1897, and on 23 February 1898 was sold for scrap.
Brown, while advocating for the ship in an 1879 issue of Proceedings, was little short of hyperbolic: “The Alarm . . . is a remarkable exception in being so free from the faults necessarily attending the practical developments of new ideas. It is true she never possessed speed—a very necessary thing for a gunboat, and a torpedo boat, but as far as carrying her battery and the working of the torpedo spars is concerned, nothing better could be desired.”