Anti-Torpedo Device Mark 29

The Mark 29 was an elaborate experimental WWII anti-torpedo defense system designed to detect and destroy incoming enemy torpedoes and was tested aboard the O’Brien. The gear was stored beneath each of the forward 20mm Antiaircraft gun tubs.

Because it contained explosives, the gun tub structure was encased in armored plating to protect the ship. To operate the system, the ship towed rubber streamers that contained explosives running parallel to the hull using an underwater glider device called a paravane. The paravane was then deployed and monitored by an underwater listening device called a hydrophone, which was used to detect the presence of any incoming torpedoes. If a torpedo was detected, the system was then armed and could automatically destroy any torpedo that passed under the streamers. 

While promising in concept, in practice it was hampered by numerous technical issues and despised by many of the ship’s crew. The Naval Armed Guard was responsible for its operation. They spent many hours struggling to deploy and recover the paravanes and their streamers, sometimes only to find they hadn’t worked properly. The deployment process also required the ship to reduce speed thereby losing its position in the convoy and thus making it more vulnerable to attack. The experiment was abandoned after the ship’s second voyage and the gear was subsequently removed.