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 ships with three masts, and two mortars, one between each neighboring pair of masts. The full rig also meant that bomb vessels could be used as escort sloops between bombardment missions; in 1805 the Acheron bomb along with the Arrow sloop were both lost in a valiant defence of their convoy. Bomb vessels often had the front rigging made of chain, to better withstand the muzzle blast of the mortars.