It is an Australian Destroyer Escort called HMAS TORRENS that had been decommissioned some years earlier. I served on her sister ship HMAS STUART as a marine engineer. We used to work below the waterline (boiler room/ engine room - the hole) exactly where the torpedo hit it.
It was a live practice exercise designed to see what a Mark 48 torpedo could do. Rather than directly impacting the hull, it's deisgned to explode underneath and the shockwave breaks the ships back.....Kinda makes ya think long and hard when you see photos like that.
Cheers
