prop cavitation

[jonut13 24]

I'm having a problem all off a sudden with cavitation causing damage to prop.  It is starting to eat away at the aluminum.  Has anyone else ever seen this.  I have had the boat 8 years with no issue but last year I put a Helix 10 on my boat.  I am thinking that the giant transducer is causing the problem.  Any suggestions on how I can correct this other than taking off the Helix?

[BP76 11]

I think folks are going to need a little more info to respond.   Size and make of boat, same for the motor.  A pic of your transom showing both transducer and motor would be good too.  I can’t see how a transducer could do that, myself, but I’m no expert.  If it is that, perhaps mounting it further out board from the motor?  

[naden 136]

Only time I’ve seen an outboard prop cavitate was when a rock guard was installed on the skeg. It could be the way the prop is wearing or is damaged that is actually causing the cavitation, I would try a new prop or have existing one welded.

[jonut13 24]

Quote

 

I will try to post some pics tonight.  It's a Crestliner 16.5   Mercury 90HP four stroke.   I have a transducer mounting block on the boat as well.  I shaved down the edges on it and moved the transducer as far right as I could.   Painted the prop.  I'll try it out this weekend as see if it is any better.

[jonut13 24]

Sorry, couldn't post pics.  But I may have found the problem. You can move the prop front to back over a 1/4" .  It is not the shaft but the prop itself moving.  Some sites say this normal ,some say any travel is not good.

Any thoughts?  Does anyone  think that this could cause the cavitation damage to the prop?

[toma-hawk 44]

Are you noticing a loss of power,or rpm of motor running higher than speed of boat.

[jonut13 24]

No, everything else seems normal.  I noticed now that there is a bushing missing off of the hydraulic lift arm.   If you grab the motor you can really move it up and down.  I'm thinking that has to be the issue, it even has some side to side travel.