New Yamaha Prop - SWS II HP

[Mozekian]

I bought a backup prop and tried it out and was very impressed with it. Solas Saturn 14.5"x15". Price is half of what the Yamaha is and the performance was very good.

 

[PartyBarge]

That low speed vibration was my experience with my SWSII prop, both the 19 and 16p. The Enertia I have on there now spins like butter so I wonder if the casting is better for Merc props or they do a better job of balancing them out of the factory. Only downside is the hub thumps more than the SDS on the Yamaha's.

I plan on sending both my props to a shop over the winter to get them labbed - I'm especially curious if they can get that vibration out of the Yam prop.

Labbing the props MAY help, but the problem is likely elsewhere. The water flow shadow created by the lower unit (among other things) effects different props differently across the speed and prop RPM range. I have seen the same thing on our I/O with some 3-blade props, even if there is nothing wrong with the prop. The four and five blade props are less prone to the problem and that is why many report that they run smoother. That said, I did have roughness develop in a Merc Hi5. Thought it needed a rebuild (may be more cost effective to just buy a new prop with a 5-blade). Turned out replacing the old torqu-flow plastic insert fixed the problem.

 

[JDB]

I agree that the problem is something other than balance as the prop is turning too slow for imbalance to really show up.
Prop imbalance that could be felt at idle speed would likely be really bad at midrange and top RPM.

Slight contact with the bore in the lower unit housing can certainly feel like a thumping and I have experienced that.

Remember these things are mounted in rubber with the thrust washer attempting to limit radial runout on the front end and nothing precisely limiting the rear end when the rubber deflects and It stands to reason that the higher rake props would exacerbate the issue.