JAXAshby wrote in message
...

water *pushed* over a rudder can cause a rudder to turn a
boat, while water "pulled" over a rudder can not.

See my other post. If conditions are such that water is
ingested from one direction, and exits in another, there is
a change in lateral momentum. That's a lateral force,
usually behind the C of G. That's a yaw. That's turning a
boat.

I think you're making the assumption (without stating it)
that, engine in reverse, water will always be ingested from
dead astern; ie, the rudder is small and of such a distance
from the prop that it has no effect on the direction of
ingestion.

JimB