Pitting/holes inside the hub of stainless steel VP duoprops

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ddurand

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The Chaparral is new to me as is boating in salt water. Have yet to use the boat. Inside the propeller hubs seems to be some holes/pitting on the SS props.

The drive is a VP DPX-A OXI and has some extras as its expected to be used in the ocean. One being "Active Corrosion Protection System".

Two questions:

1) How do I know if its just minor pitting or enough damage where the propeller(s) needs to be replaced? The blades are in perfect shape and the damage is inside the hubs.

2) The boat has the Volvo "Active Corrosion Protection System" and the proper zincs. So why is there electrolysis damage? It may have happened at a time where the zincs were needing replacement and/or the ACPS was not working. I would have thought aluminum case of the outdrive would be damaged by electrolysis before a SS propeller.
 
A propeller shop told me the hub is aluminum and rubber on these SS props. I did not know that.
 
It may be it has insufficient protection, much like older B3 drives. You may need to up the mass of the sacrificial material or add to the active system or both.
 
GeeBee said:
It may be it has insufficient protection, much like older B3 drives. You may need to up the mass of the sacrificial material or add to the active system or both.
Click to expand...
It has an active system. This all happened before I owned the boat so they may have not always plugged in shorepower.
 
Look at the irregular hole almost in the center of the picture with a hole shaped almost like a line above the irregular hole. The irregular hole seems to be through the first layer of the hub.

Does not really look like corrosion to me. Maybe a barnacle was attached there?

I am told the prop can be re hubed. But not cheap. Hub is aluminum and prop is SS (so I am told).

Maybe too small to worry about.
 

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"Hub is aluminum and prop is SS (so I am told)"

That would be hard to believe, as the aluminum would be destroyed by the SS no matter what protection you had.

Are these Volvo props or aftermarket??
 
I believe they are Volvo props. But not positive. It looks like the hub is aluminum to me. The props can be rehubed for $150 to $200. A company that does the prop work said hub was aluminum.

These props can slip on the hub and that is the main reason to rehub them. Maybe rather than damage things the SS prop is made to slip on the aluminum hub if you hit something underwater.
 
ddurand said:
Maybe rather than damage things the SS prop is made to slip on the aluminum hub if you hit something underwater.
Click to expand...
That's what Merc props do, but with rubber or plastic inserts. Always a Merc gut, never had Volvos, so I have no idea.
It just seems illogical, to me, they would put aluminum and stainless steel together.
 
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