Volvo Saildrive corrosion

No. There is no connection between the prop anodes and the drive anode as they are electrically isolated. The anodes on the prop go quickly because the prop is made of big chunks of "bronze" and stainless that don't like eachother. Nothing to worry about with the slow wear on the drive anode. Difficult to have a poor connection here if the face of the seal housing is clean and the screws holding the anode on are done up tight.
I have an Autoprop APS with an Ambassador rope cutter and when you fit the latter the prop and saildrive are no longer isolated due to the way the cutter is driven from the front face of the prop. Does it differ in the OPs case?
 
I have an Autoprop APS with an Ambassador rope cutter and when you fit the latter the prop and saildrive are no longer isolated due to the way the cutter is driven from the front face of the prop. Does it differ in the OPs case?
The stator and rotor of my rope cutter are isolated by 2 discs of nylon or similarsandwiched between 3 layers of the cutter - front layer is the rotating blade, mid layer the stator blade and the rear layer gets the drive from the prop (Volvo 3 blade folder).

Judging by the way the prop anodes disappear rapidly while the saildrive anode lasts seemingly forever, I infer that there's isolatoion between prop and saildrive. It's all dismanlted so I can't actually measure it just now.
 
The stator and rotor of my rope cutter are isolated by 2 discs of nylon or similarsandwiched between 3 layers of the cutter - front layer is the rotating blade, mid layer the stator blade and the rear layer gets the drive from the prop (Volvo 3 blade folder).

Judging by the way the prop anodes disappear rapidly while the saildrive anode lasts seemingly forever, I infer that there's isolatoion between prop and saildrive. It's all dismanlted so I can't actually measure it just now.
Mine has a similar arrangement but there are either two or three cap screws, depending on the ambassador model, that clamp the cutter plates together, which are in direct contact with the front face of the propellor. The fixed blade is also in direct contact with the saildrive via the stainless locating pin that prevents it turning. When I bought the boat it had a non OEM anode which showed next to no depletion but having switched to a Volspec it fizzes away quite happily.

As I say I have an Autoprop, a Volvo prop might be different.
 
My ambassador makes the connection between prop & saildrive. I have a Brunton Autoprop driving the cutter via 2 pins in the blade of the cutter. That blade bears on the shaft The fixed blade sits on the bearings but the connection has already been made, The fixed blade has a pin that fits into the back of a socket head screw in the saildrive so it is actually connected itself. The picture shows the rotating blade on the top right. The pin that fits in th esocket head screw can be seen on the left part just below the black plastic retaining piece
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Just taken delivery of the two part anode for a 120SD with Ambassador Stripper...

I hope it'll be a year or two before I need to report back.

View attachment 126690
So presumably the first time you fit it you will have to remove the prop to fit the backplate screws. Provided those 2 plates do not corrode you are good to go next time. However, if they do then !!!!!!!!!!!!!!!! :unsure:
I buy a standard anode & drill the hole 13.5mm diam 52mm from the centre Then cut the bit out for the fixed blade using a hacksaw. Before I had a mill I cut lots of teeth 6mm deep, like a comb & just broke them off. Fit does not have to be perfect because the anode corrodes a bit & the fit is no longer a good one anyway. This saves about £12-00 per anode for 20 mins work. May not be worth it some, but it bugs me to pay the extra for less anode
 
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