Folding prop hub damage

[robbadgie]

Hi, I removed the hub to regrease it and found these dings. Was this just caused by a rogue stone getting behind the hub or something else? Should I do anything with it - such as fill it -  before I refit or is it ok as it is? Thanks very much

[symphony2]

That looks like corrosion from galvanic action. Not a lot you can do about, although the small amount on a very substantial chunk of bronze  won't do any other harm.

[robbadgie]

Thanks for your answer. It looks like the chipped part is made out of some kind of stone/concrete rather than metal. Maybe I don't understand the materials.

[symphony2]

Clean the pits out with a Dremel and you should get back to clean yellow metal. There is no way a stone or anything else can get behind the prop.

[robbadgie]

OK thanks very much. It seemed like the part that was pitted was some kind of stone, rather than metal. When I bought this boat one anode was absent and the other wasn't fitted correctly. So it regrettably makes sense. I assume its safe to refit in this condition? At what point would it need replacing?

[JEN-et-ROSS]

Completely agree with Symphony2, it's corrosion, most likely due to the historical issue regarding the two anodes.
It's a lesson in just how quickly damage can occur. Fortunately in your case the damage is limited and future regular anode replacement will halt the process.
So the prop should have many more years of service and replacement isn't necessary......If you're concerned have a specialist company such as Darglow have a look at it before refitting ....Bill

[symphony2]

Think I was a bit hasty with my original response. You are right the chipped bit is not bronze, but is part of the cushioned hub that is pressed into bronze casting. This electrically isolates the bronze hub from the saildrive itself. It is non metallic. The questions now are what has caused the damage and is it important. You said part of the anode was missing - this might be what caused the damage if the anode eroded to the point that it broke up. Debris could have been trapped between the hub and the remaining bit of anode and caused the damage. All a bit speculative, but the upshot is that I don't think it will make any difference to the functioning of the propeller.

[robbadgie]

Thank you both for your advice. As I didn't have this from new I wasn't sure how it looked originally. Having done a bit of googling it seems there is supposed to be bronze over the top of that grey stuff, which has all gone. I'll take some pictures, fit all the anodes and check this time next year that it all looks the same.