I meant double-hulled subs designed along the lines of the Akula, Typhoon and the latest Borei class.
All of them. Trust me I used to ride them.
Typically, the U.S. has not doubled hulled anything because it is cheaper not to IF you can achieve the same results (which we can). The Ohio, with a single hull, was far stealthier than anything the Russians had---by orders of magnitude. So it didn't have to be more "survivable" to a torpedo attack, because trust me, if a torpedo gets anywhere near a sub hull (double, triple, or otherwise) you're in for a real bad day. As to faster? I've never heard this. It adds weight, so how can it be faster?
Virtually every Soviet "advantage" from their "miracle" fleet was phony. Yes, they could dive a little deeper, and the Alpha could go extremely fast . . . but Alphas had to be towed to their patrol lanes and we called them "hand grenades," as you pulled the pin and they had a limited time at that speed, then would blow up. The Soviets typically paid sailors "childlessness" pay because they didn't have sufficient radiation protection.
They used titanium because they had lots of it and it was cheap for them. But our steel was nearly as good as their titanium, and our workforce and engineers vastly superior.