CREATE TABLE table_55914 ("Date" TEXT, "Name" TEXT, "Flag" TEXT, "Tonnage  ( GRT ) " FLOAT, "Sunk by" TEXT)

What is the name of the ship sunk by U-305 on 17 March 1943?
SELECT "Name" FROM table_55914 WHERE "Date" = '17 march 1943' AND "Sunk by" = 'u-305'
SELECT "Name" FROM "table_55914" WHERE "Date" = '17 march 1943' AND "Sunk by" = 'u-305'