Volvo saildrive - folding prop de-zincing?

[chuns]

The two-blade folder on my saildrive has pink patches on it, which I assume is the bronze de-zincing. I didn't worry too much when I discovered it last winter, but a casual conversation leads me to believe that the pink patches are not just on the surface, but probably go deep, right through the blade for example.
Thinking about it, I've concluded that the anode only really protects the sail-drive leg, and that the prop itself is un-protected as it is isolated from the leg because of the shock absorber round the splines, though there is an electrical path through the securing nuts.

Is this a problem that forum-ites have a body of knowledge about, and can anyone advise me whether I am twittering needlessly, or whether I have a problem to address?

Grateful for any help, as always.

 

[bigwow]

Later Volvo folding props have anodes on them, so Volvo must have thought there was a problem with the earlier props.

 

[wotayottie]

a typical problem on this sort of installation is that the anode developes a layer of oxide between intself and the leg and becomes insulated from it. so it doesnt work.

use your multimeter top measure the resistance between the anode and the prop and also the leg. you need a good electrical circuit for the anode to work.

 

[savageseadog]

In my view normally due to stray currents from shore power. Have the teeth gone as well ?

 

[billmacfarlane]

You might this article interesting:
http://www.maxiowners.org.uk/Technical_Notes/Articles/propellers%20and%20anodes.htm

 

[roycharles]

Had the exact same problem with my bronze folder after less than one season. Luckily I obtained a refund under warranty and bought a Slipstream stainless steel folding prop which is excellent but expensive.
There have been numerous posts and discussions on this subject with many theories on the cause.
My engine - D1-20 - and saildrive - 130S - are apparently electrically insulated from each other, even the securing bolts which are fitted with electrical isolating sleeves.
VP were no help at all in suggesting a solution other than to fit a different prop.