The sails of the large clipper ship (past tense, to be) buffeted by the wind

were The phrase "to be" has several different forms depending upon present or past tense, group or individual. For present tense, we have "am", "is", and "are" which are frequently contracted. Such as "I am well" or "I'm well". The past tense forms are "was and were" where was is used for singular items and were for group items. For instance, "The sail was buffeted by the wind" as contrasted to "The sails were buffeted by the wind"