Gilbert and Sullivan’s hilarious, hopeful farce follows young Frederic, an orphan who has mistakenly been apprenticed to an ineffectual but raucous band of pirates. He disavows the pirates’ way of life and falls for the beautiful Mabel. Friday and Saturday performances are at 7:30 p.m. Sunday matinees are at 2 p.m. Adults: $21, seniors and military: $16, students: $10. NovaBillings.org