As long as men have committed robbery on the high seas, the war on piracy has been an inspiration to improve weapons and ways to use them. What we know today as the bomb ketch or bomb vessel, which saw its heyday in the 18th and early 19th centuries, is no exception.
The bomb ketch was designed at a French dockyard in the last quarter of the 17th century as a solution to the problem of battling Barbary corsairs in their own ports. Built specifically to hold and fire large mortars, the bomb ketch made it possible for naval ships to sit at anchor outside a large mole or wall and bombard the city or port beyond.
The vessel was essentially built on the lines of a three-masted ketch, a vessel slightly smaller than the standard frigate. The bomb ketch would be built or refit specifically without a foremast and her main mast would be stepped back toward her mizzen. This would allow a large foredeck with room for mortars and cannon. The ketch usually carried two mortars in her center, stepped down into areas of the ship reinforced with heavy timber. By the mid-18th century the entire vessel was exceptionally sturdy, with large beam bridges throughout to support the recoil of the mortars.
Because of the lack of foremast, the ship had to carry a long bowsprit to which standing rigging for the mainmast could be attached. The bowsprit would also carry large headsails and jibs to try and balance the square sails on her main and mizzen. Unfortunately, however, the bomb ketch was never much of a sailor with a probable top speed of only five to seven knots. She averaged around 270 tons, 205 feet in length, 28 feet at the beam and about a 14 inch draft. Despite her size she bristled with guns: one 13 inch and one 10 inch mortar plus eight 24 pound cannon was a reasonable compliment although some ketches carried more. She usually shipped about 70 hands.
The mortars themselves were large in caliber with remarkably short barrels. They fired an explosive-filled shell whose detonation was determined by the length of its fuse. Precise estimations had to be accomplished to ensure that the shell would in fact blow up where it landed rather than in the air, near the ketch or – most horrible of all – within its own mortar. The expertise needed to handle the mortars on a bomb ketch narrowed the number of men capable of working them. By the early 19th century, these mortars were worked in both the Royal Navy and the American Navy by specifically trained Marine Artillery units. Until the decline of mortars, though, when they were replaced by the more indulgent monitor, the true geniuses of their handling were the French on both sides of the Atlantic.
Because of the new technology, bomb ketches faded from use by the mid-19th century, at least as far as mortar bombardments were concerned. The ships found a new occupation in exploration, however. Because of their heavy construction they were perfectly suited to the icy conditions at both poles. Unlike other ships, they could plow through all but the thickest pack ice and winter over in frozen conditions that would have crushed better sailors as if they were made of toothpicks.
Reproductions of ketch and bomb ketch-type vessels are still being built today. An example is the lovely Royaliste sailing in San Francisco Bay, and flying the jolie rouge, in the picture at the header (via BoatingSF.com). Now that looks a lot more enjoyable than a deafening bombardment or a winter at the Antarctic, if you ask me.