hon. sir joseph porter , kcb , first lord of the admiralty ( comic baritone ) captain corcoran , commander of h.m.s. pinafore ( lyric baritone ) ralph rackstraw , able seaman ( tenor ) dick deadeye , able seaman ( bass-baritone ) bill bobstay , boatswain 's mate ( baritone ) bob becket , carpenter 's mate ( bass ) josephine , the captain 's daughter ( soprano ) cousin hebe , sir joseph 's first cousin ( mezzo-soprano ) mrs. cripps ( little buttercup ) , a portsmouth bumboat woman ( contralto ) chorus of first lord 's sisters , his cousins , his aunts , sailors , marines , etc. synopsis act i the british warship h.m.s. pinafore is at anchor off portsmouth .