CREATE TABLE table_79347 ("Year" TEXT, "Builder" TEXT, "Model" TEXT, "Length  ( ft ) " FLOAT, "Propulsion" TEXT, "Fleet series" TEXT, "Total" TEXT, "Notes" TEXT)

Which builder has a fleet series of s057-s061?
SELECT "Builder" FROM table_79347 WHERE "Fleet series" = 's057-s061'
SELECT "Builder" FROM "table_79347" WHERE "Fleet series" = 's057-s061'