DSK wrote:

One thing I'm curious about is how well they could maintain vacuum with
the turbine bypassed. IIRC the air pumps were driven off the wing engine
shafts. I don't think the Olympic class plants were designed to do
crashback drills.

One could reasonably assume that the plant was designed to accomodate
the loss of the turbine and the condenser could operate at the vacuum
required to allow full power from the recips.

Recips don't require as great a vacuum as a turbine to operate at their
peak efficiency. Plant efficiency without the turbine would drop
considerably as the energy in the recip exhaust would be lost to heating
the sea.

Recips could and would crash stop quite well, all ships are designed
with emergency backing in mind. A recip will generally stop quickly due
to the internal friction but steam can be admitted in the reverse
direction without harm ... it is a compressible fluid and acts as a
cushion in normal operation. Reversing is a simple matter of changing
the operative eccentric, all tghe parts move in the same plane as
before, only shaft rotation, thrust, and crosshead guide thrust changes,
and the engines are designed with that in mind.

Rick