Hello,
Thanks for your comments.
It should be bronze or stainless steel 316L according to the ship designer who has been helping me, as this is meant to spend years in the sea. Of course it could be possible to make a draft in brass to make sure all is ok and test the machines.
The current diameter of the larger part is 216mm but I was told I might need to shrink it to 200mm due to availability. Small changes are not a problem as this point. The smaller piece’s larger diameter is 144mm according to current plans.
Thanks for the help!
Axel