french ironclad invincible french ironclad invincible second wooden class ironclads built french_navy ships class classified armoured frigates single gun deck traditional disposition guns length hull meant broadside ironclads invincible uneventful career deployed north american waters franco prussian war timber hull quickly condemned scrapped design description designed french naval architect ships class intended fight line battle unlike british ironclads ship metres long beam metres invincible maximum draft metres depth hold metres displaced tonnes long tons ships class high metacentric height metres consequently rolled badly gun ports metres waterline proved wet crew officers enlisted men invincible single horizontal return connecting rod compound steam engine drove propeller engine powered oval boilers designed capacity indicated horsepower sea trials invincible reached knots mph carried maximum tonnes long tons coal allowed steam kilometres speed knots mph class ships initially fitted light rig masts sail area square metres later changed ship rig square metres later reduced excessive rolling class ships armed modèle millimetre rifled muzzle loading guns positioned single gun deck broadside remaining guns placed upper deck chase guns fired kilogram shell muzzle velocity metres second proved ineffective armour replaced rifled breech loading modèle guns millimetre guns mounted centre gun deck pair millimetre guns replaced original chase guns invincible wooden hull completely armoured wrought iron plates millimetres thick backed millimetre sides hull armour extended metres waterline metres class ships open topped conning tower armour millimetres thick millimetres armour underneath wooden upper deck construction service ordered march invincible laid arsenal toulon launched april completed march september october conducted tactical trials ironclads assigned mediterranean_fleet ship port visit august brest fleet hosted festivities invincible banquet fleets reportedly enjoyable visit days later french fleet visit portsmouth hosted channel_fleet franco prussian war ship sent defend islands prussian commerce raiders built timber invincible poor shape return decommissioned condemned august ship scrapped
French ironclad Invincible