Vibration-Outdrive or Prop??

[trswenson]

Ok I did something really stupid and need an opinion or two.
I beached my boat on a fairly shallow sand bar. Not uncommon, but I didn't lift my outdrive very high, started the boat to leave and engaged the tranny and it killed the motor. Well stupid me did this 3-4 times before realizing the outdrive was too low and the prop was stalling the motor. Now that I admit my lack of intelligence here's the issue; the prop was a brand new SOLAS 4 blade 17 pitch aluminum. The outdrive is a Volvo-Penta SX. At very low speeds (wakeless) there is a significant vibration with the new prop. There is no visible damage to the prop, still looks brand spankin' new. I changed props and the vibration is very very slight, not even sure it's there. At Plane or higher speeds no vibration with any of the props.
So did I damage the prop and can't see it with the naked eye or is there some internal damage to the outdrive. First thing to do is have it checked out I know, but I had trailered the boat 10 hours to lake Powell and left it there for 2 weeks until we go back for a 10 day vacation. The trailer is locked up so it's not gonna make it to my normal shop 'till I get home.
What cha all think I did to it?

 

[Zeusdafreak1]

Re: Vibration-Outdrive or Prop??

Wow! Don't feel bad. I'll be willing to bet everyone here has done something stupid at one time or another. It's called "learning. LOL I ate an aluminum prop up on a concrete landing before I realized exactly where the end of my foot was. I bet I never do that again.

I can't answer your question but I bet some of these guys will have some ideas of what may being going on. Good luck.

 

[sabastianunf]

Re: Vibration-Outdrive or Prop??

My experience is that you have to ding a prop pretty good to throw it far enough out of balance to be noticable through a vibration. I have an old 3 blade I use as a spare. It has a couple of good chips in it but you can not feel any vibration comming from it. I almost bought a solas 4 blade a couple of months ago - I went with a Michigan wheel vortex 4 blade instead. I was just wondering if you noticed the 5-10% HP incease they claim you get from their props?

 

[trswenson]

Re: Vibration-Outdrive or Prop??

The boat definitely gets through the RPM's quicker than my 3 blade of the same pitch (17), and has slightly better top end too. I don't have another 4 blade to compare it to though. But after the vibration I took it off and only have about 2-3 hours with it, so maybe 5% but not 10.

 

[Texasmark]

Re: Vibration-Outdrive or Prop??

Rotate the prop while measuring the hub clearance and blade tip clearance to an immovable object....like a concrete driveway with the I/O vertical and the boat on a trailer. ANY eccentric movement is your problem.

Since you can't see anything and have the vibration, you may have damaged the prop hub. Bending a propshaft is also an option, but a lot would be bent up if you went that far.

Mark

 

[walleyehed]

Re: Vibration-Outdrive or Prop??

It would be pretty tough to bend the shaft with an aluminum prop...My bet is that 1 or more of the blades has a progressive bend that you just don't notice. My money is on the prop being the culprit.

 

[trswenson]

Re: Vibration-Outdrive or Prop??

Texas & Walley --- many thanks I'll have a good look at it soon !!