Hi all, Not wanting to upset the apple cart and all that, and turn this thread into a long too's and fro's argument but......
The subject of propellor design rotation/rudder/rudder size is not a simple topic. What Shipmates60 has done is simplify a very complicated subject which, at the end of the day, does not have any definite solutions.
It has been proven time after time that two people can build identical models - yet one of the models performs better than the other in some way. So therefore, if Shipmates60, for arguments sake, has built (like he says 4 models of this vessel) and DickyD is building one they may look identical, but, they may perform totally different in the water. So, as regards hard and fast rules of props and rudders, it is generally a case of the old saying 'suck it and see' - nobody is right and nobody is wrong on this subject.
Further good reading, if anyone does wish to read into this is a book called HighSpeed Small Craft by Peter Du Cane. I warn you for propellor/rudder design its very heavy reading - there are a lot of mathematics involved.
Aye
John E
BLUEBIRD