Summary

The Lay Torpedoes were designed by John Louis Lay.

Lay enlisted in the United States Navy in July 1861 and in 1864 was responsible for introducing Lieutenant William Barker Cushing to offensive torpedo warfare. Cushing later used a spar torpedo perfected by Lay to sink the Confederate ram Albemarle at Plymouth, North Carolina, on October 27, 1864.

Lay conducted further work on torpedoes at the Philadelphia Navy Yard and in 1865 he and Chief Engineer W. W. W. Wood took out four patents relating to torpedoes and torpedo warfare (US Letters Patent No's 46,850-46,853, dated March 14, 1865). Lay resigned from the navy in 1865 and was engaged by the Peruvian government to assist in the preparations of the defences of the harbour at Callao.

He returned to the United States in 1867 where he perfected the "Lay Moveable Torpedo Submarine." Described as being not unlike a contemporary Whitehead fish torpedo the Lay Moveable torpedo came in two lengths namely sixteen and twenty-three feet. The torpedoes were cylindrical in cross-section with conical ends and had warheads carrying 100 or 200 pounds of explosive. The bodies of the torpedoes were divided into sections or compartments. The first of these carried the explosive charge, the second the gas reservoir or holder, the third contained the apparatus for holding and paying out the control cable and an upper compartment contained the engine and the steering apparatus. The torpedoes were provided with a single screw propeller, a double screw propeller or two screw propellers. Powered by a 9 indicated horse-power motor driven by compressed carbon dioxide or ammonia a twenty-three foot Lay torpedo achieved a trial speed of 9 miles per hour. The most important feature of Lay's design was the fact that unlike the Whitehead torpedo which was a "fire and forget" weapon the Lay torpedo was controlled by a ship or shore based operator via a multi-core insulated electric cable dispensed from the torpedo.

Following demonstrations held in both the United States and Europe the Russian Government purchased the manufacturing rights, built a factory in Russia and having imported the plant, machinery and skilled labour from America reportedly manufactured 10 of the large Lay torpedoes. Having made and lost a fortune in Europe Lay returned to America where he died homeless and destitute in New York's Bellevue Hospital on Monday April 17, 1899.

The Lay torpedo, though mechanically advanced and promising in theory and practice, was not widely adopted as it was very costly. In 1878 a single Lay torpedo was worth USD 15,000.