I served on TRUNCHEON(1951) and TIPTOE(1952) before they were converted and write the odd article on submarine propulsion such as http://tinyurl.com/htdsrpw . I cannot recall the gun tower arrangement on a G3 T , in particular the twin upper gun hatches ( I was an electrician ).I wondered if you could confirm that there were indeed two upper hatches and whatever was in the lower part of the gun access trunk . Most grateful
Peter