Your standard of workmanship, and attention to detail, is seriously impressive - there are many Bismarck models out there in various scales but it's rare to see one of this level of precision.
A couple of questions: What are the filler/drain screws on the rudder for? (it sounds like the rudder is hollow and intended to be filled with water?) Are they a feature of the real ship, or only on the model?
And are the cooling water inlets intended to be functional on the model (as intakes or outlets for the motor water cooling pipes?) I don't think I've ever seen a model, of any ship, which replicates these to the level of detail you have, with the internal ducting/pipework fully modelled.