DSK wrote:

DSK the marine propulsion expert wrote:

In any case, the ship was going full speed, the loss of the prop
stream across the rudder would not reduce the rudder's effectiveness
very much.




Nav wrote:

http://www.dellamente.com/titanic/engines5.htm


Interesting web site. Thanks for the link.

It does contain a number of inaccuracies, though.


"Regardless, most scenarios agree steam to the turbine would have been
cut off. While this had little effect on the ship's forward motion,


???

The central turbine was about 35% ~ 40% of the ships forward power. How
is it going to have "little effect on the ship's forward motion?"

Or do they mean that shutting off steam to the turbine would not have
produced significant stopping impulse? That would be much more correct.


Yes, that's what they mean.

They also don't appear to know how the reciprocating engines were reversed.


Why introduce this irreelevance?


... it deprived the rudder of the steady, forceful stream of water
necessary to turn a ship of that size.


???

A steady stream of water goin 22 + knots is not "forceful"?


I expect you don't know this but the effect of wake can reduce rudder
effectiveness. In Titanic's case, the rudder was in the "shadow" of the
hull which further reduced it's effectiveness in the absense of
propwash. The difference in turning circle can be 50% (even at full
speed) for inline rudders. Next time you are out on your tug try it at
full speed -you can measure easily measure your turning circle with a
chart plotter. You increase in turning circle with the prop stopped will
be reduced if you rudder is free of hull obstruction but I'll predict
the difference will be at least 20%. Try it, its an important lesson for
the masters of power vessels -if you want to manouver hard, go to full
power and throw the rudder right over (~30 degrees).



... Several sources claim the rudder on the Titanic and her sister
ships was too small. If that was indeed the case, shutting down the
center turbine would be the last thing you would want to do in an
emergency."


The "rudder too small" claim is total malarkey. The Olympic was the same
design and had a long service career, with a reputation of being a good
handling ship.


Well they are experts but you say they know less than you Doug. I find
your posturing amazing. You have no idea how her rudder area compares to
the accepted norm and yet you say they are wrong. Amazing. In Doug's
world you are always right of course.

Cheers