One way I look at acoustics (the few times I'm still alive when they are available) is we put up insane tonnage numbers and sink our fair share of capital ships. I think our 'renown' would be high enough to get whatever we wanted after 1,000,000 tons.
While I'm here talking about torps a question (I think the answer is no): you can't change your load out of torps after you've left port can you?
Like if you have 4 acoustics loaded in your tubes but come across a couple of unescorted merchants and don't want to waste acoustics on easy shots - can you change those for ones you have in reserve?