Lyle gun
Line-throwing guns are most often referred to as Lyle Guns, after their inventor David A. Lyle. They were used from the late 19th century to 1952, when they were replaced by rockets for throwing lines.
A line-throwing gun is a short-barreled cannon designed to fire a projectile attached to a rope to a boat or victim in distress. Experiments in shooting tethered projectiles dates back to around 1800. A mortar device was credited with saving lives as early as 1850.
One of the first actions of Superintendent Sumner Increase Kimball, the only superintendent of the U.S. Life-Saving Service, was to find a better line-throwing device. Kimball realized he needed the best artillery expertise available, so he engaged the help of the Army Board of Ordnance and in 1877 they assigned David A. Lyle, First Lieutenant, U.S.A (1845–1937), a West Point and MIT graduate who began research and testing that resulted in reliable efficient designs. Lyle developed 3 bronze, smooth-bore guns of different sizes and the 2 1⁄2-inch-bore (64 mm) gun became the USLSS standard line-throwing gun.
Projectiles for the gun were made of cast iron with a wrought iron eye bolt screwed into the base as an attachment point for the shot line. The projectile for the 2 1⁄2-inch (64 mm) gun was 15 3⁄4 inches (400 mm) long and weighed 19 pounds (8.6 kg). It was placed into the 24-inch-long (610 mm) gun barrel so the eye bolt with the line attached was sticking out. After firing, the projectile rotated so that the eye bolt and line were trailing. The gun had a large recoil from firing. A standard charge of 1.5 ounces (43 g) of gunpowder would knock the gun back 6 feet (1.8 m). The maximum rescue charge of 8 ounces (230 g) would send the gun flying back even further.
The type of gunpowder used was also critical. It was a variation of black powder,uniform grain size, marketed as Hazard’s Life-Saving Service Powder and DuPont Life-Saving Powder.
...
Wikipedia