▁was ▁power ed ▁by ▁three ▁ 4 - cy l inder ▁vertical ▁triple ▁expansion ▁steam ▁engines ▁with ▁ 1 5   bo ilers ; ▁each ▁engine ▁drove ▁a ▁four - bl aded ▁sc rew . ▁The ▁ship ' s ▁engines ▁were ▁r ated ▁at ▁ ▁and ▁produced ▁a ▁top ▁speed ▁of ▁. ▁Ost f ries land ▁stored ▁up ▁to ▁ ▁of ▁coal , ▁which ▁allowed ▁her ▁to ▁steam ▁for ▁ ▁at ▁a ▁speed ▁of ▁. ▁After ▁ 1 9 1 5 ▁the ▁bo ilers ▁were ▁modified ▁to ▁sp ray ▁oil ▁on ▁the ▁coal ; ▁the ▁ship ▁could ▁carry ▁up ▁to ▁ ▁of ▁fuel ▁oil . ▁She ▁had ▁a ▁crew ▁of ▁ 4 2   o ffic ers ▁and ▁ 1 , 0 7 1   en list ed ▁men . ▁ ▁Ost f ries land ▁was ▁armed ▁with ▁a ▁main ▁battery ▁of ▁twelve ▁ ▁SK ▁L / 5 0 ▁guns ▁in ▁six ▁tw in ▁gun ▁tur rets , ▁with ▁one ▁tur ret ▁fore , ▁one ▁a ft , ▁and ▁two ▁on ▁each ▁fl ank ▁of ▁the ▁ship . ▁The ▁ship ' s ▁secondary ▁arm ament ▁consisted ▁of ▁four teen ▁ ▁SK ▁L / 4 5 ▁guns ▁and ▁four teen ▁▁ ▁SK ▁L / 4 5 ▁guns . ▁After ▁ 1 9 1 4 , ▁two ▁of ▁the ▁ 8 . 8   cm ▁guns ▁were ▁removed ▁and ▁replaced ▁by ▁ 8 . 8   cm ▁anti - air craft ▁guns . ▁Ost f ries land ▁was ▁also ▁armed ▁with ▁six ▁ ▁sub mer