After seen that outstanding and impressive technology a question comes to mind, if they know beyond the shadow of a doubt that by installing a shroud around a propeller increase the efficiency near '40 percent why they don't do it?

I find it interesting to see that none of the steps are particularly hard to understand; at the same time all the steps are made difficult be the sheer size of the objects, and the whole project becomes quite complicated.

And here are the azipods and the descent ship with a standard propeller, propeller shaft, simplex or sederval, gearbox and main internal combustion engine and most likely a two-stroke one?

The ABB Azipod is an alternative power source, it provides a reduction in diesel fuel and carbon footprint, up to 35 percent. It was initially tested in Ferries,, then in used in freighters,, tankers,, cargo and cruise ships. It is now used in super yachts. It has nothing to do with how they make propellers. Sorry your description it is a bit misleading to people.

I don’t understand how they can keep seawater from migrating into the shaft assemblies through the seals.