alma class ironclad alma class ironclads group seven wooden armored built french_navy mid late 1860s ships attempted blockade prussian ports baltic_sea franco prussian war patrolled north_sea atlantic ship route japan war began blockaded small prussian ships japanese harbor alternated periods reserve active commissions abroad ships participated french occupation tunisia helped accepting status french played small role sino french war design description alma class ironclads designed improved versions armored corvette suitable foreign deployments unlike predecessor ships true central battery ironclads fitted armored transverse bulkheads original plan ships deck battery millimeter guns battery deck millimeter guns mounted upper deck gun corner battery design changed substitute barbettes upper battery addition armored bulkheads proved heavy rear pair barbettes deleted save weight partial compensation millimeter guns remaining forward barbettes replaced additional pair millimeter guns like ironclads era equipped metal reinforced ram ships built general plan differed measured meters perpendiculars beam meters ships mean draft meters displaced metric tons long tons crew numbered officers men propulsion alma class ships single horizontal return connecting rod steam engine driving single propeller engine powered oval boilers sea trials engine produced indicated horsepower ships reached knots mph unlike single funnels arc funnels mounted ships carried metric tons long tons coal allowed ship steam nautical miles speed knots mph barque rigged masts sail area square meters armament ships mounted millimeter modèle breech loading guns central battery battery deck millimeter guns mounted barbettes upper deck sides ship millimeter guns mounted upper deck alma ship positively known exchanged guns newer guns armor piercing shell caliber gun weighed pounds gun weighed long tons gun fired shell muzzle velocity credited ability penetrate nominal inches wrought iron armour muzzle guns fire solid shot explosive shells armor alma class ships complete millimeter wrought iron waterline belt approximately meters high sides battery armored millimeters wrought iron ends battery closed bulkheads thickness barbette armor millimeters thick backed millimeters wood portions sides protected millimeter iron plates construction service franco prussian war arc assigned attempted blockade prussian ports baltic ordered return september cruised north_sea later watched prussian corvette portuguese waters alma route far_east war began blockaded pair prussian harbor arrived japan end war ships placed reserve sent foreign stations flagship arc spent time spanish waters protect french citizens interests ship rammed sank dispatch vessel july rammed run ashore prevent sinking abroad alma bombarded port july french occupation tunisia participated august attack french forts defending mouth leading vietnamese capital attempt vietnamese government sino french war ship early september carried admiral taiwan september
Alma-class ironclad