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Propeller Shaft "Flaking"

2K views 6 replies 7 participants last post by  Fstbttms 
#1 ·
I had the boat hauled today for a bottom painting. While there I was told by the yard that the cutlass bearing was bad. He showed me this by shaking the prop shaft and said there was too much play. When he did this some of the prop shaft "flaked off" and revealed some of the shaft that was pink. He said that the zincs were gone and the shaft was compromised. He said that the shaft would likely break and fall off in time. To replace the cutlass bearing and shaft - $900-$1000. Is this reasonable? Has anyone ever seen a shaft in this condition? Oddly, the propeller was in excellent condition, no growth or damage.
 
#2 ·
I did mine myself. How long ago were the zinks last replaced? If it was recent find out why they are gone and fix it. Could be electrical leakage. You have a bigger problen than just the cutlass bearing. If you replace it and dont fix the problem you will be replacing it all over again.
 
#3 ·
If the shaft is bronze, and it is pinkish, it is likely a victim of galvanic corrosion of some sort. Don't know if the price is reasonable or not, as I don't have any specifics on the boat.
 
#5 ·
Take a picture of it and post it here.
I think changing the cutlass bearing would be enough and you could easily do it yourself.
I have serious doubts that "He said that the shaft would likely break and fall off in time" is anyhting other than sharp practice, and poorly worded.
 
#6 ·
Your costs for replacement, etc. sound correct, although you could DIY for less. As to whether you wish to replace the shaft, that's your call. Personally, I'd go stainless and find your galvanic corrosion problem. Me thinks your marina is the culprit. Hang a zinc off your battery's negative terminal over the side if you need more protection. You still need to find the cause.
 
#7 · (Edited)
Your shaft has suffered dezincification due to electrolytic or galvanic corrosion. The pinkish color indicates that the zinc component of your bronze shaft has been depleted (this why we use sacrificial anodes) and the shaft material is now seriously weakened and brittle. If it's bad enough that metal is actually flaking off the shaft, I would replace the shaft.

This kind of damage is unlikely to occur in a short period of time. While it's possible there is some electrical problem that is the root cause of this (most likely to be aboard your own boat, rather than a neighbor's or the shorepower system), it sounds like the boat has been unprotected by zincs for quite a while. You absolutely need to make sure your zincs are replaced periodically.
 
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