Question: What's the departed date for Grimsby class sloop?
SQL: SELECT "Date departed" FROM "2-16814676-2" WHERE "Class" = 'Grimsby class sloop';

Question: What's the departed date that the HMS Leith of the Royal Navy?
SQL: SELECT "Date departed" FROM "2-16814676-2" WHERE "Navy" = 'Royal Navy' AND "Name" = 'HMS Leith';

Question: What's the class of the HMS Fowey?
SQL: SELECT "Class" FROM "2-16814676-2" WHERE "Name" = 'HMS Fowey';

Question: What's the class of the HMS Heartsease?
SQL: SELECT "Class" FROM "2-16814676-2" WHERE "Name" = 'HMS Heartsease';