Low RPM Vibration

Danishgod

Handymans342

Could be Drive/engine alignment

randy56

Props new, could be bent, thats all that you changed.

212rowboat

i have a ron hill marine prop.. it's flawless.  
there has been a lot of talk about ron hill marine props here lately, and singing their praises. 
i have a buddy and he ordered a ron hill marine prop after trying mine on his boat and it performing very well- and his is a visibly out of balance, shoddily made PoS...
when they're good they're outstanding.  
when they aren't, they are terrible. 
they cost too much to consider rolling the dice by my reckoning, and i hate it- because when they're good they're very good. 

that said....... check your fasteners.