Bomb vessel A bomb vessel , bomb ship , bomb ketch , or simply bomb was a type of wooden sailing naval ship . Its primary armament was not cannon ( long gun s or carronade s ) — although bomb vessels carried a few cannon for self - defence — but rather mortars mounted forward near the bow and elevated to a high angle , and projecting their fire in a ballistic arc . Explosive shells or carcasses were employed rather than solid shot . Bomb vessels were specialized ships designed for bombarding ( hence the name ) fixed positions on land . In more modern times , the same role was carried out by battleship s , cruiser s and destroyer s , as well as the purpose - built World War I - and II - era monitors . Development . It is generally accepted that the first bomb vessels were built at the end of the 17th century , based on the designs of Bernard Renau d ' Eliçagaray , and used by the French Navy . They were first called " gáliote à bombe " ( a word derived from the Dutch galliot denoting a short , beamy vessel well suited for the powerful downwards recoil ) . Five such vessels were used to shell Algiers in 1682 destroying the land forts , and killing some 700 defenders . Two years later the French repeated their success at Genoa . The early French bomb vessels had two forward - pointing mortars fixed side - by - side on the foredeck . To aim these weapons , the entire ship was rotated by letting out or pulling in a spring anchor . The range was usually controlled by adjusting the gunpowder charge . The French later adopted the word " bombarde " for this vessel , but it should not to be confused with the horizontal fire , stone throwing bombard of earlier centuries . The French design was copied by the Royal Navy , who continued to refine the class over the next century or more , after Huguenot exiles brought designs over to England and the United Provinces . The side - by - side , forward - pointing mortars were replaced in the British designs by mortars mounted on the centerline on revolving platforms . These platforms were supported by strong internal wooden framework to transmit the forces of firing the weapons to the hull . The interstices of the framework were used as storage areas for ammunition . Early bomb vessels were rigged as ketches with two masts . They were awkward vessels to handle , in part because bomb ketches typically had the masts stepped farther aft than would have been normal in other vessels of similar rig , in order to accommodate the mortars forward and provide a clear area for their forwards fire . As a result , by the 1800s British bomb vessels were designed as full rigged ship s with three masts , and two mortars , one between each neighboring pair of masts . Bomb vessels often had the front rigging made of chain , to better withstand the muzzle blast of the mortars . Mortars were the only kind of naval armament to fire explosive shells rather than solid shot until the invention of p aixhans gun . Since it was considered dangerous to have large stocks of shells on board the ships that were firing them , and because the reinforced mortar platforms occupied so much space below decks , bomb vessels were usually accompanied by a tender to carry ammunition as well as the ordnance officers in charge of firing the mortars . However as naval warfare became more advanced ' Bomb Ships ' were also accompanied by normal cannon holding frigates to protect them from direct assault , by faster , smaller vessels . Bomb vessels were traditionally named after volcanoes , or given other names suggestive of explosive qualities . Some were also given names associated with the underworld . Vessels of other types which were later converted to bombs generally retained their original names . Bomb vessels were highly specialized and expensive to fit out and maintain , and only marginally suited for their secondary role as cruisers . Because bomb vessels were built with extremely strong hulls to withstand the recoil of the mortars , several were converted in peacetime as ships for exploration of the Arctic and Antarctic regions , where pack ice and icebergs were a constant menace . Most famously , these ships included HMS " Erebus " and HMS " Terror " . In this case , the volcanoes – Mount Erebus and Mount Terror on Ross Island in Antarctica – were named after the ships , instead of vice - versa . Although horizontal fire naval guns propelling explosive shells had entered all major navies by the 1840s ( see Paixhans gun ) , there was still room for a specialized vessel on occasion . During the American Civil War , the Union fleet included armored gunboats armed with 13 inch mortars ; the weapon weighed 17 , 250 lbs and its bedding another 4 , 500 lbs . They fired 204 - lb shells , with a bursting charge of 7 lbs of gunpowder , and had a range of three miles . At this distance , the projectile spent 30 seconds in flight . They were used to attack several forts , for example Fort Pulaski , Georgia . In fiction . The Commodore ( published 1945 ) , a Horatio Hornblower novel written by C . S . Forester , features several actions by British bomb vessels . The text includes a highly detailed account of the procedures used to load the mortars and aim , which involved anchoring fore - and - aft , receiving feedback from shot monitors , and precisely adjusting the aim using a spring - line attached to a windlass to adjust the direction of the shot , and by using sometimes tiny adjustments in the amount of charge to adjust the range . It is worth noting that Hornblower ' s vessels are named " Harvey " and " Moth " , suggesting that Forester might have been unaware of the historical naming conventions . A later book Hornblower in the West Indies , features a small portable " ship ' s mortar " mounted in a boat , used to bombard a target during a riverine operation .