Darman wrote:Theemile wrote:Sadly, this has me thinking about a hedgehog launcher - a WWII weapon which was essentially a few dozen mortars mounted together to create a pattern of destruction wherever they are aimed - the shipborne issues would be compounded - except for the accuracy bit, since a hedge hog is an aim-over-there-ish weapon.
This was my thought too. A hedgehog or katyusha-type weapon (although I would not want to be the one firing rockets from aboard any wooden ship) firing shells/warheads with incendiary "shrapnel" might be effective.
Keep in mind that the US Army, when considering coastal defense requirements at the end of the 19th century, considered the smallest number of coastal defense mortars (12" mortars, pre-sighted, fixed fortified positions, fixed aiming points, invulnerable to all incoming fire except mortar fire) to be 4 mortars in a diamond formation. And even that was half a battery. Most coast defense installations built at the time included at a minimum 16 mortars per position to bracket the enemy warship with as many shells as possible. This should give you some idea of the challenges of aiming these mortars from dry land. Add in a ship pitching and yawing every which way? No way. Not with the minimal number of mortars you'd be able to fit on a galleon (i.e. one or two at most). Again, the Army's Coast Defense Artillery expected 16 mortars firing at once from fixed positions at pre-sighted coordinates to be effective at taking out an enemy battleship.
Given the difficulty of a direct hit, and the relative ineffectiveness of blackpowder propelled shrapnel from a mortar shell I wonder if you'd be better off trying for something closer to the original hedgehog; underwater explosions using high-explosive. Of course the fuses would have to be changed since the hedgehog was contact fused; it only detonated if it hit a sub. You'd want something that went off at roughly 7-10 feet underwater. But screw gallies have very lightly build hulls; a series "nearby" high explosive underwater detonation might cause significant leaking.
OTOH that requires more resources and time than simply diverting some existing army mortars and ammo onto ships - you'd have to design and build a new mount and ammo. By that point The Cities or KHs should have already shown up - and they've guns that'll blow right through the bow armor on a screw galley. (Not to mention when working in pairs either design has the steam powered mobility split up so a screw galley can't keep it armor pointed at both simultaneously; giving a free shot at the galley's unarmored flank).