CREATE TABLE table_4477 ("Number" TEXT, "Name" TEXT, "Meaning" TEXT, "Fleet" TEXT, "Launched" TEXT)

when was the number l6, with a fleet of black sea, launched?
SELECT "Launched" FROM table_4477 WHERE "Fleet" = 'black sea' AND "Number" = 'l6'
SELECT "Launched" FROM "table_4477" WHERE "Fleet" = 'black sea' AND "Number" = 'l6'