Voices of Science

What actually was ASV11? 

It was a radar which, like the H2S radar that gave the bombers a picture of the land underneath it, it gave you a picture of the sea underneath you. You were looking for submarines, submarines are not that stupid; they have a breathing pipe called a snorkel. If a sea wasn’t too rough you didn’t get echoes from the waves you would see a snorkel of a submarine charging itself. Which was quite something. Between the wheels of the Swordfish, remember it hadn’t got a retractable undercarriage, is a radome, a blob inside which the scanner rotates, it spins around, sends out a narrow beam which scans the sea. And that is between the wheels. So very good looking forward, not terribly good looking sideways when the wheels get in the way, and it blocks the path of a torpedo, you can’t carry one. Well you don’t drop torpedoes on submarines, you have either rockets or bombs or depth chargers, which were fitted with. 

How effective actually is this system for hunting submarines?

Oh extremely effective.