Maciek.
It is always good to have a statement confirmed, you are an expert for finding written confirmations. The torsional vibration dampers varies in design, as your info on the GW and MAN engines mention. One is f.i. mechanical, the other is hydraulical. I believe for the earlier boats they had a torsional vibration meter fitted. I cannot remember we had any. In the 1930 years it was not common to carry out relative complex torsional vibrations calculations for shaft systems, so I guess you had a torsionalmeter to monitor same. But as I said, there have been VIIC shaftbreakages due to torsional vibration stresses and may be they started to make more complex torsional vibration calculations after that and installed a better tailormade vibration damper at a later stage. Just a theory from my side. The Rooths blower created torsional vibration as well and the drive had another mechanical vibration damper. After the war torsional vibration calculations became mandatory for all seagoing vessels and has to be submitted to the classification societies for approval. The barred rpm range varied considerably between a 6 cylinder and a 9 cylinder engine (IXC) as well as to which inertia masses you connected E-motors propeller etc. so you can not put up rpm valid for more than one cylinder- and mass configuration.
You mainclutch operatings instruction fit very well with my experience, but I would`t like to use 350 rpm as a standard. The wear would require frequent adjustments and even renewal of the friction layer.
