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Volvo 81 Jack Shaft Duo Prop Cavication Burns

N

njfishing

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I have a 25 foot Carolina Clas

I have a 25 foot Carolina Classic with an 8.1 Jack Shaft with a Volvo Penta Duo Prop and am running Aluminum B6 props. The engine runs just at the edge of the WOT rpms reccomended (4500) so I think I am propped correctly...

I have some pretty severe issues with what I am told are cavication burns on the aft prop to the extent that I am forced to replace the aft prop every year... It burns through the base of the prop where it meets the hub and pratically burns through the aluminum.

When I first purchased the boat it had a 7.4 amd was running B5 props and never had this issue..

Wondering if anyone else has had this issue and some things I might try to overcome it...

Thanks.
 
"mmmm... I don't have any

"mmmm... I don't have any experience personally with this HOWEVER there are a few things I would consider.

1) Are you sure that BOTH props are from the B6 set?
2) There has been talk on other posts in the past about "indexing" the front and rear props, i.e., installing the rear prop so that it has a particular relationship to the front prop.
3) Is the front prop's hub slipping?
4) Was the front prop repaired at any time in the past?

Just some shots in the dark here...."
 
Thanks Robert... Yes both are

Thanks Robert... Yes both are B6s...Not 100% sure but I don't think the front prop hub is slipping as this happend on a brand new set of B6s...

I've heard about the indexing thing and tried it to no avail...
 
"Now I'm really scratching

"Now I'm really scratching my head. One last SWAG ( Screaming Wild A-- Guess).

How do you keep the drive trimmed?

OK... two SWAGS... If you look at the hull and the drive from the side when on the hard, what is the (vertical) relationship between the cavitation plate on the drive and the bottom of the hull?"
 
We generally keep the drive tr

We generally keep the drive trimmed up a few inches from it's lowest point.

The cavication plate of the drive is below the bottom of the hull...
 
"Ricardo - If C means stainles

"Ricardo - If C means stainless, no I have not... I keep my boat in the water 8 months of the year and was told by the people from Carolina Classic that there were a lot of people experiencing some severe cases of electrolysis when using the stainless props..I'd be interested if you have heard of these issues...


A quick update.... Took the rear prop to be reconditioned to a very reputable shop. The owner suggested that there must be some sort of design flaw that Vovlo will not admit to since he sees a lot of props with the same issues...

Thanks for your help and suggestions Ricardo..."
 
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