Lewin of Greenwich Naval History & Forum

The J Class comprised seven boats, all completed during the First World War. This Class was fitted with four bow tubes and two beam tubes and were capable of 19 knots on the surface. J6 was the only war casualty from the Class when she was mistakenly sunk by a Q ship off Blyth in Northumberland. Post war, they were transferred to the Royal Australian Navy.
Some photos:

Beam tubes , now I am proving my ignorance Jim