I know you can crash dive a boat to max testing depth. Normally the boat making a crash dive level off at 160 feet +/-. What button, key or dial do you hit to have them go straight to maxmum depth. The crash dive button?
My problem is not dud torpedoes. I have seen lots of them. My problem is avoiding dds after I have launched an attack. They always find me. The torpedoes say,

"I am so happy to have found you! I was afraid you had left without saying goodbye. Glad you stuck around. Love Ducimus."