Best propeller for a 2013 RT 21ec 30 hp Yanmar?

[jnlparr]

Hello fellow Tugnuts,
We have enjoyed our tug immensely over the last year and half. I hesitate to even bring up the topic for fear of hearing the collective groan of "not this again", but.... what is the best propeller for Hazel Nut?
2013 RT 21ec 30 hp Yanmar
Max RPM? I believe the manual states MAX RPM 3600. Max WOT under load? Most efficient fuel consumption RPM? And what that boat speed might be?
What do you run on your boat? What would you choose if you could do it differently?
I plowed a little sand just off of Bat Water Station in the Columbia River (the locals are now all chuckling) and I have a chance to replace the factory propeller or? I've been encouraged to try a three blade. Better traction while maneuvering? I have some concerns with cavitation hammering the hull?
Cruising the Portland metro area and the Columbia River basin.
MV Hazel Nut,
Jim

 

[Capt’nKarl]

Good morning Jim. I have the original 4 blade prop on my 2009 21EC. I don’t know the specs but really don’t have any issues. I have the 3YM30 Yanmar as well. When I flush the engine with fresh water I get a WOT tach reading of 3950 rpm without a load. I typically cruise at 2900 rpm which gives me a speed of 6-7 knots depending on conditions. WOT under load is around 3600 rpm.
Cheers,
Karl