CREATE TABLE table_55401 ("Ship's name" CLOB, "Date entered service" CLOB, "Date withdrawn" CLOB, "Tonnage" FLOAT, "Type of Ship" CLOB)

what is the least tonnage for the ship(s) that entered service on 11 february 1983?
SELECT MIN("Tonnage") FROM table_55401 WHERE "Date entered service" = '11 february 1983'
SELECT MIN("Tonnage") FROM "table_55401" WHERE "Date entered service" = '11 february 1983'