Volvo Penta Prop has no anode -Is this OK?

[rosie]

I have acquired an old Volvo Penta two bladed folding prop PN 385563 as a spare for my existing prop. However, while cleaning it up I have just realised that there is nowhere to fit an anode on the hub unlike my current hub which is designed to take a 3 segment zinc anode. The prop is listed as obsolete on VP websites so I can't find any info about it but clearly it must have been ok in its day without an anode. Can anyone shed any light on why it was ok with no anode then but not now? I have noticed that prop hubs by other manufacturers do not appear to have anodes fitted. Am I likely to bring about disaster if I use this hub without an anode?
Your prop wisdom would be appreciated!


Dave.

 

[eilerts]

No disaster. This prop is protected by the anode on the leg, because it is not electrically insulated from rest of the drive. It will eat this anode faster than you are used to, because of all the bare metal on the prop. I had this old type for 10 years with no problems (came with the boat), until a catastrophic corrosion event destroyed my drive, and I destroyed the hub while trying to get it off the shaft. I were used to change the anode on the leg every year, I could have pushed it to two years, but saw little reason for that. The newer version is supposed to be electrically insulated from the drive, that why you need the segmented anode.

 

[rosie]

Many thanks for your prompt wisdom! I will fit prop with confidence.

 

[roaringgirl]

I'm not sure this advice is good - it will depend on your setup. Is your prop electrically isolated from your engine? On my boat, there's a wire that deliberately jumps the gap over the insulating coupling on the transmission.

 

[Tranona]

I'm not sure this advice is good - it will depend on your setup. Is your prop electrically isolated from your engine? On my boat, there's a wire that deliberately jumps the gap over the insulating coupling on the transmission.

Suspect the OP has a saildrive and the prop has a solid hub so is connected to the anode on the leg through the shaft. Later Volvo props have rubber hubs to isolate them from the drive and do indeed need their own anodes. As the OP says, not all folding props (like the Flexofold 2 blade I had for many years on a saildrive) need an anode. My current boat (shaft drive) will have a 3 blade feathering propeller which has its own anode, because it is a mixture of stainless and bronze, but no hull anode connected to the shaft.

 

[Neeves]

From memory, which maybe defective, my 2 bladed, folding Gori prop had no anode - the anode was on the Bukh sail drive.

Jonathan

 

[rosie]

Thanks for your responses. It is indeed a saildrive VP 110S and the prop does have a solid hub. The erosion of the saildrive anode has never been heavy so now that I understand the situation a bit more I am content to fit the prop. I can always dry out (twin keel) & see how it is going.

 

[eilerts]

Thanks for your responses. It is indeed a saildrive VP 110S and the prop does have a solid hub. The erosion of the saildrive anode has never been heavy so now that I understand the situation a bit more I am content to fit the prop. I can always dry out (twin keel) & see how it is going.

The hub on your old spare is not solid. The spline cylinder is aluminium, the outer shell is brass, and there is rubber in between, just as the newer ones, but spline cylinder touches the brass. As far as i can see, the shaft is not electrically insulated from the leg, so there you have your connection to the anode. I have cut open my old hub. You are welcome to cut your hub, too, if your are in doubt