CREATE TABLE table_59613 ("Ship" TEXT, "Tonnage" TEXT, "Builder" TEXT, "Original Operator" TEXT, "Fate" TEXT)

What is the Tonnage that has builder AG Vulcan, and the original operator NDL, and the ship, Prinzess Irene?
SELECT "Tonnage" FROM table_59613 WHERE "Builder" = 'ag vulcan' AND "Original Operator" = 'ndl' AND "Ship" = 'prinzess irene'
SELECT "Tonnage" FROM "table_59613" WHERE "Builder" = 'ag vulcan' AND "Original Operator" = 'ndl' AND "Ship" = 'prinzess irene'