Originally Posted by
DuncanDoenitz
Not my speciallist subject I must add, but I can't see it happening. Terrestrial based ICBMs are housed in concrete silos which can tolerate the high temperatures and pressures of an initial boost-phase motor, as well as accommodating ducting for the exhaust gasses. Can't see that on a surfaced sub where the weapons are packed in like sardines, and I don't know how else you are going to get the missile far enough from the host vessel to avoid damage.
I don't think the only other option is to hot-launch the missile! Being on the surface does not preclude the launch tubes from being flooded, and in any case public-source information suggests that the steam generator is separate from the launch tube. It is more complex than surface-only cold-launch systems because it has to work underwater, but there is no reason to think that it wouldn't work on the surface.