CREATE TABLE table_name_54 (tonnage VARCHAR, u_boats_destroyed__kuk_ VARCHAR, ships_sunk__pola_ VARCHAR)
What is the listed Tonnage that has U-boats destroyed (KuK) of 2 and Ships sunk (Pola) of (not recorded)?
SELECT tonnage FROM table_name_54 WHERE u_boats_destroyed__kuk_ = "2" AND ships_sunk__pola_ = "(not recorded)"