I know this isn't the answer to your question, but it does give me a chance
to mention the variable/reversing pitch system used on a few Navy and some
commercial ships that require quick response in maneuvering.

The diesel engines drive into a reduction gear (and only have a clutch to
disconnect an down engine). The prop shaft run out of the independent gear
box where the thrust bearing is normally located.

The prop is has a hub with hydraulic mechanisms that rotate the synchronized
multiple blades from either side of "0" pitch (neutral) to fwd or reverse.

The hydraulic control of this blade assembly comes through an Oil
Distribution Box (OD Box) on the extreme inboard end of the prop shaft. The
shaft end rotates inside this box and the hydraulic oil pressure is
transmitted down two passages bored from this inboard end, down to the hub
end where it is can act on the prop blade mechanism to rotate the blade.

This may sound overly complex but it eliminates the need to stop and reverse
the engines while maneuvering. Much less complex than reversing gears for
engines of these HPs.

The one problem I encountered while dealing with these system was from total
loss of hydraulic pressure. The prop blades seem to have a mind of their own
and as long as the engine is running/engaged the prop continues to rotate
and may switch from "0" pitch to full astern (my experience) or full ahead.


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions