Harpoon cannon
A harpoon cannon is a
Harpoon cannons are still used by whaling nations, but these are usually guns of a smaller caliber. The exception is Iceland, which hunts large whales regularly.
History
Early engineers attempted to develop gun-fired harpoons to improve the hit rate from hand-thrown harpoons, generally with little success, as the guns were not very accurate, especially when fired from small moving whaleboats. Another problem appeared when the quarry were
Design
Early cannons were muzzle-loading, but were replaced later with breech-loading models. These are used in modern whaling, with the exception of many Norwegian cannons which utilize an improved muzzle-loading design, with a breech firing system. In the early 20th century, almost all cannons were similar to the Kongsberg 90 mm design. With a trigger mounted on the back of a steel handle which would lever a thin rod up to the firing device in the horizontally sliding breechblock. To load, the rear cover plate would be rotated, exposing the back of the rectangular breechblock. The breechblock would be opened by rotating a handle on the top of the breech, and the spent cartridge case removed, to be reloaded with powder and wadding. A new cartridge would be prepared and slid up into the firing chamber, the breechblock would be closed by rotating the handle counterclockwise, the rear cover would be rotated back to cover the rear chamber, a harpoon would be prepared, inserted into the muzzle, and tied on. Then another rotating handle on the side of the breechblock would be pulled back to cock the firing pin. This handle was directly adjacent to the firing trigger on the block. The gun was solid steel, and had a glycerin recoil cylinder mounted under the barrel. The inner barrel and breech would bounce back on the recoil, while the handle and swivel in the deck would be mounted on a stationary outer cylinder.
21st century
All of the above countries utilize Norwegian-designed PETN grenades to improve the humaneness of the kill, with the exception of Japan, which uses domestically manufactured grenades, which have proved less effective at guaranteeing an instant kill (40% instant death rate in Japan vs. 80% in Norway).