▁protection ▁was ▁light , ▁with ▁ 2 - inch ▁( 5 0 . 8 ▁mm ) ▁gun ▁shield s ▁and ▁con ning ▁tower , ▁and ▁a ▁ 1 . 5 - inch ▁( 3 8 . 1 ▁mm ) ▁deck ▁extending ▁ ▁over ▁the ▁mach in ery ▁spaces . ▁ ▁The ▁engineering ▁plant ▁included ▁eight ▁coal - f ired ▁cyl ind rical ▁bo ilers ▁producing ▁ ▁steam ▁and ▁a ▁horizontal ▁comp ound ▁engine ▁producing ▁ ▁driving ▁one ▁sh aft . ▁Like ▁the ▁other ▁" AB CD " ▁ships , ▁Boston ▁was ▁built ▁with ▁a ▁sail ▁rig ▁to ▁increase ▁cru ising ▁range , ▁later ▁removed . ▁The ▁ship ▁carried ▁up ▁to ▁ 4 9 0 ▁tons ▁of ▁coal , ▁with ▁a ▁cru ising ▁range ▁as ▁built ▁of ▁ ▁at ▁. ▁ ▁Ref its ▁In ▁ 1 9 0 0 – 0 1 ▁Boston ▁was ▁re built ▁and ▁the ▁ 6 - inch ▁guns ▁were ▁converted ▁to ▁rapid ▁firing ▁with ▁br ass ▁case ▁am mun ition ▁replacing ▁pow der ▁b ags . ▁During ▁her ▁service ▁with ▁the ▁Oregon ▁Naval ▁Milit ia ▁ 1 9 1 1 - 1 6 ▁she ▁retained ▁her ▁original ▁pair ▁of ▁ 8 "/ 3 0 ▁guns ▁and ▁three ▁of ▁the ▁ 6 "/ 3 0 ▁guns , ▁with ▁a ▁single ▁/ 4 0 ▁cal iber ▁gun ▁added . ▁All ▁arm ament ▁was ▁removed ▁prior ▁to ▁her ▁conversion ▁to ▁a ▁fre ighter ▁in ▁ 1 9 1 7 . ▁ ▁Service ▁history ▁ ▁Pre - Span ish – American ▁War ▁(